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Volume 65 (2016): Edition 1 (December 2016)

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Volume 61 (2012): Edition 1-6 (December 2012)

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Volume 59 (2010): Edition 1-6 (December 2010)

Volume 58 (2009): Edition 1-6 (December 2009)

Volume 57 (2008): Edition 1-6 (December 2008)

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Volume 55 (2006): Edition 1-6 (December 2006)

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Détails du magazine
Format
Magazine
eISSN
2509-8934
Première publication
22 Feb 2016
Période de publication
1 fois par an
Langues
Anglais

Chercher

Volume 57 (2008): Edition 1-6 (December 2008)

Détails du magazine
Format
Magazine
eISSN
2509-8934
Première publication
22 Feb 2016
Période de publication
1 fois par an
Langues
Anglais

Chercher

52 Articles
access type Accès libre

Genetic Variation of Anatolian Black Pine (Pinus nigra Arnold. subsp. pallasiana (Lamb.) Holmboe) in the Lakes District of Turkey

Publié en ligne: 14 Oct 2017
Pages: 1 - 5

Résumé

Abstract

In this study, morphological characteristics of juvenile 1- and 2-year-old seedlings of Anatolian black pine were studied to estimate the amount of genetic variation and heritability of seedling traits of the species in the Lakes District of Turkey. This nursery study involved 460 parent trees from 23 populations in a randomized complete block design. Traits studied were the number and length of cotyledons, hypocotyls and epicotyls lengths, weight and length of initial roots, height, root collar diameter, and stem and root fresh weights, and number of buds. Variation was higher among than within populations with individual tree heritability ranging from 0.09 to 0.76, whereas family mean heritability ranged from 0.16 to 0.80. Genetic and phenotypic correlations between juvenile and 1-year-old seedling traits were generally the same sign and magnitude. Variation and heritabilities were higher for growth-related traits than the number and length of embryonic tissues. The observed level of population differentiation was low, possibly due limited geographic sampling of populations, which spanned only 2° of latitudes and longitudes, and 300m in elevation. If the observed heritabilities for growth traits were sustained to tree maturity combined family and within family selection would be effective in improving growth of this species in the Lakes District of Turkey. A broader geographic sampling is recommended for better estimation of population differentiation and establishment of the geographic pattern of the species in this region.

  • Keywords Pinus nigra
  • genetic variation
  • heritability
  • seedling traits
access type Accès libre

Chromosomal Mapping of 18S-25S and 5S Ribosomal Genes on 15 Species of Fagaceae From Northern Thailand

Publié en ligne: 14 Oct 2017
Pages: 5 - 13

Résumé

Abstract

Fifteen species of Fagaceae from Chiang Mai province, northern Thailand, were investigated: eight Castanopsis, four Lithocarpus and three Quercus species. The species were generally diploid with the chromosome number 2n = 24, and the basic number x =12 was confirmed in some species with meiosis. One tree belonging to Q. lenticellatus had 2n = 14. Chromosomal mapping of the highly repetitive 18S-25S and 5S ribosomal genes by fluorescence in situ hybridisation (FISH) was performed. Most species (from all three genera) showed four 18S-25S rDNA sites (two pairs: one subterminal major and one paracentromeric/intercalary minor loci) and two 5S rDNA sites (one pair: paracentromeric locus). Quercus kerrii also had two pairs of 18S-25S rDNA sites, but both were subterminal major loci. Two species, C. argentea and Q. brandisianus, only had one pair of 18S-25S rDNA sites. Two species, C. calathiformis and L. vestitus, showed an odd number of (unpaired) sites, and this indicated hybrid origin and/or polyploidy. Polyploid cells were detected in these species. The ribosomal gene maps based on both sequences together were genus-specific. In Castanopsis, the 18S-25S and the 5S genes were localized on three different chromosome pairs, and comprised species-specific maps. On the other hand, the ribosomal genes in Lithocarpus and Quercus were found only on two chromosome pairs, because one of the two 18S-25S rDNA loci was localized on the same chromosome as the 5S rDNA locus. The FISH markers may be used to clarify discrepancies arising from morphological assessments.

Mots clés

  • Fagaceae
  • Castanopsis
  • Lithocarpus
  • Quercus
  • fluorescence in situ hybridisation (FISH)
  • ribosomal gene mapping
  • 18S-25S and 5S rRNA genes
access type Accès libre

Evaluation of Early Rooting Traits of Eastern Cottonwood That Are Important For Selection Tests

Publié en ligne: 14 Oct 2017
Pages: 13 - 21

Résumé

Abstract

Vegetative propagation of superior genotypes via stem cuttings depends on their development of strong vigorous root system. Fourteen characters of cutting rooting were examined in multiannual tests with 12 genotypes of eastern cottonwood (Populus deltoides BARTR. EX MARSH) in course of evaluation of their utilization in selection tests. Variability and relationship among examined characters, and cutting survival rate were analyzed according to contribution of expected variances to the total variance and results of principal component analysis, stepwise regression analysis and path analysis. Along with total number and length of first-order roots, the characters that are regularly used in the assessment of rooting potential, our results signify dynamic shoot growth and uniform arrangement of roots on cutting at the beginning of growing period. The best results were obtained for shoot height at the second half of May. A rapid and non-destructive way of shoot characters’ measurement allows testing of larger material and prevents losses in propagation material of interesting genotypes. Alone or together with total root number and length these alternative characters could be used for the improvement of selection tests and procedures for cultivar technology design.

Mots clés

  • Populus deltoides
  • cutting rooting characters
  • cutting survival rate
  • multivariate analysis
access type Accès libre

An Evaluation of Selection for Volume Growth in Loblolly Pine

Publié en ligne: 14 Oct 2017
Pages: 22 - 28

Résumé

Abstract

Total inside-bark volume is the most important selection criterion for productivity in tree breeding programs in the Southeastern U.S. Tree breeders typically estimate total inside-bark volume based on outside-bark diameter at breast height and total height without accounting for stem taper or bark thickness. To make a direct determination of total inside- and outside-bark volume, a loblolly pine (Pinus taeda L.) open-pollinated family trial replicated with cultural treatments of weed control and fertilization was measured. This direct measurement was compared to typical volume estimates. In this trial, approximately 40 individuals from each of 25 open-pollinated first- and second-generation families were destructively sampled in the 13th growing season. Selection for volume using a combined-variable (diameter2 * height) equation was found to be highly effective for making volume gain. There was a high correlation between estimated and directly-measured total inside-bark volumes (0.99). Bark thickness and stem taper had low importance for stem volume selection. There was a positive genetic correlation between bark thickness and diameter at breast height (0.66). This indicates that selection for larger diameters may produce individuals with thicker bark, which may eventually affect total inside-bark volume estimates.

Mots clés

  • bark thickness
  • genotype by treatment interaction
  • stem taper
  • volume gain
  • Pinus taeda L.
  • stem volume
  • tree improvement
  • stem form
access type Accès libre

Genetic Diversity of Hippophae rhamnoides Populations at Varying Altitudes in the Wolong Natural Reserve of China as Revealed by ISSR Markers

Publié en ligne: 14 Oct 2017
Pages: 29 - 36

Résumé

Abstract

Hippophae rhamnoides L., a dioecious and deciduous shrub species, occupies a wide range of habitats in the Wolong Nature Reserve, Southwest China. Our present study investigated the pattern of genetic variation and differentiation among five natural populations of H. rhamnoides, occurring along an altitudinal gradient that varied from 1,800 to 3,400 m above sea level in the Wolong Natural Reserve, by using ISSR markers. Based on fingerprinting patterns generated by fifteen primers, high levels of genetic variation were present within populations and subpopulations. Substantial genetic divergence was observed among populations, and also among female and male subpopulations, the GST values equaling 0.182, 0.222, and 0.238, respectively. Such considerable divergence present among populations and subpopulations may be caused by complex topography which effectively restricts gene flow, and by variable climatic conditions at different altitudes which may cause varying selective pressures. A significantly positive correlation between genetic and altitudinal distances was detected for the five populations and female subpopulations of H. rhamnoides. The cluster analysis including all populations or male subpopulations resulted in three altitude groups. Our results suggest that altitudinal gradients may be the prime cause affecting the genetic variation pattern of different populations and subpopulations in H. rhamnoides in the Wolong Nature Reserve, Southwest China.

  • Keywords Altitudinal gradients
  • Genetic variation
  • Hippophae rhamnoides
  • ISSR markers
  • Sex-specific genetic differentiation
access type Accès libre

Triploid Induction in Populus alba x P. glandulosa by Chromosome Doubling of Female Gametes

Publié en ligne: 14 Oct 2017
Pages: 37 - 40

Résumé

Abstract

Efficient methods for obtaining unreduced female gametes are needed for triploid induction in Populus alba x P. glandulosa. A cytological study of MMCs and PMCs meiosis and staminate floral elongation revealed that there was a close association between MMCs meiotic stage and male bud phenology during development under the same environment conditions. Female buds of Populus alba x P. glandulosa were treated with 0.5% colchicine solution at the selected meiotic stages based on male bud phenology. The treated buds were pollinated with pollen of P. tomentosa. A high rate of unreduced female gametes occurred in late leptotene and pachytene stages of MMC, as evidenced by a relatively higher percentage of triploids in the progeny, when compared to progeny from colchincine application at other meiotic stages. The present results demonstrated that male bud phenology can be used to guide colchicine applications to female buds and cause a more efficient production of triploids.

Mots clés

  • chromosome doubling
  • effective treatment stage
  • female gamete
  • Populus alba x P. glandulosa
  • triploid
access type Accès libre

Short Note: Development of Mitochondrial Markers for Population Genetics of Norway Spruce [Picea abies (L.) Karst.]

Publié en ligne: 14 Oct 2017
Pages: 41 - 44

Résumé

Abstract

Norway spruce is an important commercial tree species in northern and central Europe. Pure mitochondrial DNA isolated from tissue culture materials grown in the dark were used to construct a partial mitochondrial library. 100 clones were randomly selected and 19 markers were isolated. Three of these markers proved to be polymorphic and two showed maternal inheritance in controlled crosses. These markers will be useful for population genetic studies in P. abies.

Mots clés

  • mtDNA
  • marker development
  • maternal inheritance
  • population genetics
  • length polymorphism
  • null alleles
  • Picea abies
access type Accès libre

Direct and Competition Additive Effects in Tree Breeding: Bayesian Estimation From an Individual Tree Mixed Model

Publié en ligne: 14 Oct 2017
Pages: 45 - 56

Résumé

Abstract

An individual tree model with additive direct and competition effects is introduced to account for competitive effects in forest genetics evaluation. The mixed linear model includes fixed effects as well as direct and competition breeding values plus permanent environmental effects. Competition effects, either additive or environmental, are identified in the phenotype of a competitor tree by means of ‘intensity of competition’ elements (IC), which are non-zero elements of the incidence matrix of the additive competition effects. The ICs are inverse function of the distance and the number of competing individuals, either row-column wise or diagonally. The ICs allow standardization of the variance of competition effects in the phenotypic variance of any individual tree, so that the model accounts for unequal number of neighbors. Expressions are obtained for the bias in estimating additive variance using the covariance between half-sibs, when ignoring competition effects for row-plot designs and for single-tree plot designs. A data set of loblolly pines on growth at breast height is used to estimate the additive variances of direct and competition effects, the covariance between both effects, and the variance of permanent environmental effects using a Bayesian method via Gibbs sampling and Restricted Maximum Likelihood procedures (REML) via the Expectation- Maximization (EM) algorithm. No problem of convergence was detected with the model and ICs used when compared to what has been reported in the animal breeding literature for such models. Posterior means (standard error) of the estimated parameters were σ̂2Ad = 12.553 (1.447), σ̂2Ac = 1.259 (0.259), σ̂AdAc = -3.126 (0.492), σ̂2 p = 1.186 (0.289), and σ̂2e = 5.819 (1.07). Leaving permanent environmental competition effects out of the model may bias the predictions of direct breeding values. Results suggest that selection for increasing direct growth while keeping a low level of competition is feasible.

Mots clés

  • competition effects
  • individual tree mixed model
  • additive and direct competition effects
  • estimation of additive (co)variances
  • Gibbs sampling
access type Accès libre

Inheritance and Genetic Gain in Wood Stiffness in Radiata Pine Assessed Acoustically in Young Standing Trees

Publié en ligne: 14 Oct 2017
Pages: 56 - 64

Résumé

Abstract

Wood stiffness, measured in terms of its modulus of elasticity (MoE) is an important characteristic of radiata pine for structural products. To select high stiffness radiata pine for breeding purpose, rapid, inexpensive methods for measuring wood stiffness are desirable. In this study, we explored acoustic instruments to measure stiffness of young standing trees in radiata pine and examined inheritance and genetic gain for stiffness in an Australian national breeding program. Time of flight of sound waves was recorded in standing trees in two progeny trials, one in eastern Victoria (Flynn) aged 8 years and the other in South Australia (Kromelite) aged 7 years. Average time of flight at Kromelite was higher than at Flynn, (519 μs/metre compared to 463 μs/metre) which corresponds to 3.7 GPa and 4.7 GPa for MoE, respectively. Heritability for time of flight was higher at Flynn (h2 = 0.67 ± 0.10) than at Kromelite (h2 = 0.30 ± 0.14). Selection of the best 10% for time of flight based on pooled data would result in 21% genetic gain in wood stiffness.

Mots clés

  • wood stiffness
  • acoustics
  • heritability
  • genetic gain
  • radiata pine
access type Accès libre

Construction of a Populus tremuloides Michx. BAC library

Publié en ligne: 14 Oct 2017
Pages: 65 - 69

Résumé

Abstract

We have constructed an aspen (Populus tremuloides Michx., line Turesson141) BAC library containing 55,296 clones in total. A random sampling of 86 BAC clones indicated an average insert size of 76 kb with a range of 20 to 160 kb. Twelve percent of the BAC clones in the library have an insert size larger than 100 kb. Based on an estimated genome size for Populus of 500 Mbp, library coverage is about 8 haploid genome equivalents. This library will be screened using AFLP marker identified before co-segregating with gender in a P. tremula x P. tremuloides progeny, where Turesson141 was the male parent.

Mots clés

  • Bacterial Artificial Chromosome
  • Populus
  • genome size
  • aspen
access type Accès libre

Crossing Success in Abies nordmanniana Following Artificial Pollination With a Pollen Mixture of A. nordmanniana and A. alba

Publié en ligne: 14 Oct 2017
Pages: 70 - 76

Résumé

Abstract

Controlled crossings were conducted with three Abies nordmanniana genotypes acting as mothers and a pollen mixture of three Abies nordmanniana genotypes and one Abies alba genotype acting as potential fathers. The aim was to investigate hybridization success under circumstances where pollen from both species are present, which is a potential risk in Danish clonal seed orchards of Abies nordmanniana. The number of seeds sired by each father was determined through SSRs and compared to the expected numbers based on the pollen mixture composition. All three mother genotypes of Abies nordmanniana had more progenies with the Abies alba as father (hybrids) than expected, based on proportions in the pollen mix. This indicates that no reproductive barriers between the two species exist, and that seed orchard managers should take precautions to avoid hybrids in seed crops. Furthermore, the experiments revealed quite different siring success of the three Abies nordmanniana genotypes, depending on which clone was the mother. Abies nordmanniana seed orchards should therefore not be established in the vicinity of Abies alba in the flowering age, and if a few-clone set up is chosen, the mating interaction should be investigated beforehand through pollen mix experiments.

Mots clés

  • Abies nordmanniana
  • Abies alba
  • hybridization
  • pollen mixture
  • seed orchard contamination
access type Accès libre

Spontaneous Hybridization between Pinus sylvestris L. and P. mugo Turra in Slovakia

Publié en ligne: 14 Oct 2017
Pages: 76 - 82

Résumé

Abstract

Molecular evidence for spontaneous hybridization between Pinus sylvestris L. and P. mugo Turra in the putative hybrid swarm populations of the species in Slovakia was provided based on PCR-RFLP analysis of the cpDNA trnV-trnH region. Species-specific restriction profiles generated by Hinf I digests of the cpDNA products reliably identified P. sylvestris and P. mugo haplotypes of the embryos from open pollination. Simultaneous analysis of the respective cpDNA region in megagametophytes and embryos of individual seeds along with needles of a given maternal tree has enabled to score either the P. sylvestris or P. mugo haplotypes in the embryos illustrating hybridization patterns between the two species. Data obtained in this way indicate a relatively extensive hybridization which takes place between P. sylvestris and P. mugo. The extent of hybridization varied among populations as evidenced by the 41.1-58.7% proportion of hybrid embryos registered on the locality Habovka, and by the 8.3% and 2.7% proportions of hybrid embryos on the localities Tisovnica and Sucha Hora, respectively. The approach itself is recommended as a convenient method for monitoring the hybridization patterns in sympatric zones of the studied pine species.

Mots clés

  • Pinus sylvestris L.
  • P. mugo Turra
  • hybridization
  • chloroplast DNA
  • restriction analysis
access type Accès libre

Primer Note: A New Set of Highly Polymorphic Nuclear Microsatellite Markers for Nothofagus nervosa and Related South American Species

Publié en ligne: 14 Oct 2017
Pages: 82 - 85

Résumé

Abstract

Nothofagus is the main component of southern South American temperate forests. Overexploitation in the past has led to the loss of 40% of the original distribution range. Genetic diversity as well as biological processes shaping the distribution of the genetic variation (e.g. gene flow) constitutes basic knowledge for the implementation of conservation measures and for the definition of Evolutionary Significant Units. Nuclear microsatellites are the marker of choice for gene flow and fine-scale genetic structure studies. We enlarged a previous set of microsatellites (SSRs) for South American Nothofagus species, with special concern to Nothofagus nervosa (Phil.) Dim. et Mil. Five new SSRs are presented with allele numbers up to 12 in a single population. The primers transferred well to five related species (N. obliqua (Mirb.) Oerst, N. glauca (Phil.) Krasser, N. dombeyi (Mirb.) Oerst , N. pumilio (Poepp et Endl.) Krasser and N. antarctica (G. Forster) Oerst, with allele numbers up to 11. The high level of polymorphism promises a sufficient power for gene flow and parentage analyses.

Mots clés

  • Nothofagus
  • microsatellites
  • South America
  • gene flow
  • fine-scale genetic structure
access type Accès libre

Genetic Variation in the Qinghai-Tibetan Plateau Endemic and Endangered Conifer Cupressus gigantea, Detected Using RAPD and ISSR Markers

Publié en ligne: 14 Oct 2017
Pages: 85 - 92

Résumé

Abstract

Assessing the level and distribution of genetic diversity of rare tree species is essential for their management and the development of effective conservation strategies. Cupressus gigantea is a long-lived endemic cypress of the west Qinghai-Tibetan Plateau and the tallest tree in its genus. The current populations of this species are fragmented and highly disturbed. We used RAPD (Random Amplified Polymorphic DNA) and ISSR (Inter-Simple Sequence Repeat amplification) markers to assess the genetic variation and population structure of this endangered cypress. The 15 RAPD primers used in this study amplified 108 reproducible bands, 49 (45.4%) of which were polymorphic, while the 12 ISSR primers amplified 94 bands, 65 (69.2%) of which were polymorphic. Analysis of Molecular Variance (AMOVA) indicated that 49.7% and 38.3% of the variation was attributable to differences between populations for the RAPD and ISSR markers, respectively; relatively high compared to values reported for other conifer species. These estimates were also similar to Gst values obtained from Nei’s gene diversity analyses (RAPD = 0.41 and ISSR = 0.36), and suggest that there is a high degree of population differentiation in this narrowly-distributed conifer. The genetic structure of this species has probably been shaped by its long life cycle and climatic changes during the Quaternary. The high degree of population differentiation in this species highlights the need for additional conservation measures, including measures to protect of all of the remaining populations. The substantial similarities between the results of the RAPD and ISSR analyses of samples from the same individuals indicate that they can be interpreted with high levels of confidence.

Mots clés

  • Cupressus gigantea
  • genetic diversity
  • ISSR
  • RAPD
  • Qinghai-Tibetan Plateau
access type Accès libre

Comparison of Genetic Structure Assessed by Amplified Fragment Length Polymorphism and Retrotransposon-based Sequence-specific Amplification Polymorphism for Portuguese Populations of Pinus pinea L.

Publié en ligne: 14 Oct 2017
Pages: 93 - 100

Résumé

Abstract

In order to assess genetic diversity within and among populations of Pinus pinea L. (stone pine), seven Portuguese populations originating from three Provenance Regions were selected and genotyped using two marker systems. We compared the genetic variation of these populations using retrotransposon-based sequence-specific amplification polymorphism (SSAP) and amplified fragment length polymorphism (AFLP). In total, 105 trees were screened with three primer enzyme combinations (PEC), producing 232 SSAP and 132 AFLP loci. Where SSAP yielded approximately twice-the number of polymorphic fragments compared to AFLP. Differentiation was slightly higher for SSAP, than for AFLP (FST = 0.105 for SSAP and 0.074 for AFLP), and both significantly different from zero, P < 0.01. The levels of average genetic diversity within-population found with the two types of marker were not significantly different between SSAPs and AFLPs (26.6% and 22.8%, respectively). The populations that displayed the highest and lowest genetic diversity scores were the same for both markers, and only two populations had significantly different He estimates. The neighbor-joining tree based on the Nei’s genetic distance displayed some geographic pattern. With the AFLP markers the populations grouped according to the provenance regions where they were sampled, resulting in one well supported cluster with the Southern populations, but with SSAP the pattern was not so coherent. In this study SSAP generated more polymorphic fragments and higher estimates of genetic diversity than AFPL did, due, probably, to the higher mutation rate of retrotransposition relative to base mutation. Nevertheless, congruence was found between estimates obtained with both markers, which is very interesting, for, in general, SSAP markers have lower costs compared to AFLPs, and they might be an interesting alternative marker system, when higher resolution is requested.

Mots clés

  • sequence-specific amplification polymorphism
  • amplified fragment length polymorphism
  • Pinus pinea
  • genetic structure.
access type Accès libre

Genetic Parameter Estimates for Growth Traits from Diallel Tests of Loblolly Pine Throughout the Southeastern United States

Publié en ligne: 14 Oct 2017
Pages: 101 - 110

Résumé

Abstract

Variation in heritability and in genetic correlation estimates were evaluated for juvenile tree height and volume for six testing areas of loblolly pine (Pinus taeda L.) in the southeastern United States. Variance components and their functions (heritability and type B genetic correlations) were estimated from 265 six-parent disconnected diallel series, tested in almost 1000 trials (4 tests per diallel series). Original data were collected at age 6 years from about one million trees (265 diallel series x 30 crosses x 36 trees per cross/site x 4 sites) planted in field tests. Genetic tests were from the second cycle of breeding in the North Carolina State University - Industry Cooperative Tree Improvement Program. The overall unbiased individual-tree narrow-sense heritability for height was 0.19 and for volume was 0.16. The broad-sense heritabilities for height (0.24) and for volume (0.22) were higher than narrow-sense heritabilities due to the presence of non-additive genetic variance. There were moderate regional differences in these estimates, with tests in the Lower Gulf Coastal Plain tending to have the highest heritabilities for growth traits. There was very little association between site index and heritability, but heritabilities were higher on sites with the highest survival and highest test precision. Genotype x environment interactions were generally low both for half-sib and full-sib families, indicating that families can be operationally deployed to different sites with little concern about unpredictable performance.

Mots clés

  • Genetic correlation
  • genetic gain
  • genotype x environment interaction
  • heritability
  • Pinus taeda L.
access type Accès libre

Genetic Variation in Reproductive Traits in a Clonal Seed Orchard of Prunus avium in Northern Spain

Publié en ligne: 14 Oct 2017
Pages: 110 - 118

Résumé

Abstract

In the present study we investigated the reproductive phenology of Prunus avium in a seed orchard located in northwestern Spain. The study was carried out with 103 clones from 7 provenance regions in northern Spain. The most advanced flowering stage on different dates and the number of flowers and cherries were monitored over two consecutive years. Significant differences among clones were found for all of the studied traits, with high broad-sense heritability estimates for all, except duration of flowering and synchronization index, both of which showed moderate heritability. In general, there was good overall reproductive synchronization in the seed orchard, although two groups of clones were differentiated. Clones from two out of the seven populations studied flowered later and were less well synchronized. The clonal differentiation was correlated with geoclimatic variables, suggesting that clones from lower altitudes and higher temperatures tend to an earlier flowering.

Mots clés

  • Wild cherry
  • genetic variation
  • flowering
  • genetic parameters
  • reproductive synchronization
  • geographic pattern
access type Accès libre

Strategies for Optimal Deployment of Related Clones into Seed Orchards

Publié en ligne: 14 Oct 2017
Pages: 119 - 127

Résumé

Abstract

This study deals with how the deployed proportion of each candidate clone can be decided at the establishment of a seed orchard when the breeding values are available for each candidate in a population of unrelated half-sib families. The following deployment strategies were compared: (a) truncation selection by selecting the clones with the breeding values exceeding certain threshold and deploying equal number of ramets (Truncation strategy); (b) truncation selection by selecting only one best individual within each family (Truncation unrelated); (c) maximizing gain at a given effective clone number (Linear deployment); (d) linear deployment by selecting one best individual within each family (Linear deployment unrelated) and (e) maximizing net gain at a given gene diversity (Optimal proportions). The study focused on the latest alternative and described its superiority and characteristics for a number of possible typical cases. The genetic gain adjusted for predicted inbreeding depression (Net gain), gene diversity and effective clone number were considered as the main ranking criteria. The strategies optimizing the number of related individuals and the linear deployment strategy with restriction on relatedness returned the highest Net gain. If there is a large diversity to select from (the status number of the candidates is more than 8 times greater than the status number desired in the seed orchard), a relatively simple advice is to select the best individual within the best families and deploy the clones linearly according to their breeding values (the number of families selected depends on the desired status number). If the diversity available to select from is small, it seems recommendable to allow half-sibs among the selections and use the Optimal proportions deployment strategy. As the breeding cycles proceed, the status number of the candidate population will decrease and the Optimal proportions strategy is likely to become more favorable.

Mots clés

  • co-ancestry
  • gene diversity
  • genetic gain
  • inbreeding
  • seed orchard
  • status number
access type Accès libre

Crossability Between Wild (Malus sylvestris) and Cultivated (M. x domestica) Apples

Publié en ligne: 14 Oct 2017
Pages: 127 - 130

Résumé

Abstract

Malus sylvestris, a native fruit tree of Europe, is believed to be threatened by hybridization with the omnipresent cultivated apple (Malus x domestica). In the present study a series of controlled crossings were carried out in order to establish whether M. sylvestris can hybridize with its near relative, M. x domestica. By looking at fruit set, seed production, germination percentages, and development of seedlings following inter- and intraspecific crossings, no indication of neither pre- nor postzygotic barriers to hybridization between the two species was found. This can have important implications for management of the genetic resources of M. sylvestris.

Mots clés

  • Malus sylvestris
  • Malus x domestica
  • crossability
  • hybridization
  • conservation
access type Accès libre

Provenance by Site Interaction of Pinus densiflora in Korea

Publié en ligne: 14 Oct 2017
Pages: 131 - 139

Résumé

Abstract

Thirty-six provenances of Pinus densiflora were evaluated for stability and adaptability for height growth at 11 test sites in Korea. The data were obtained from measurements at age 6 and analyzed using linear regression model and AMMI (additive main effect and multiplicative interaction) model. There was significant provenance by site interaction effect (p < 0.011). The interaction term explained 7.1% of total variation. While the regression model accounted for 15.8% of GxE interaction term, the AMMI model accounted for 74.9% with four PCA values. Most of the provenances were not significantly different from the unity (b =1.0), except for Inje (1), Jungsun (4), Bongwha (5), Koryung (26), Hamyang (30) and Seoguipo (36). Adaptability of provenances to the test sites was estimated with mean height growth and first AMMI component scores (IPCA 1). Inje (1), Bongwha (5), Taean (20) and Seoguipo (36) were specifically adapted to the high yielding environments. Considering the first and second AMMI components (IPCA 1 and IPCA 2, respectively) scores, Whachun (2), Samchuk (10), Joongwon (14) and Buan (29) provenances were more stable than others. The implication of GxE interaction was discussed in view of seed transfer and delineation of seed zones.

Mots clés

  • linear regression model
  • AMMI model
  • provenance test
access type Accès libre

Mixed Mating With Preferential Outcrossing in Acacia saligna (Labill.) H. Wendl. (Leguminosae: Mimosoideae)

Publié en ligne: 14 Oct 2017
Pages: 139 - 145

Résumé

Abstract

Acacia saligna is being developed as an agroforestry crop for the southern agricultural regions of Australia. This study investigated the breeding system of A. saligna to generate basic knowledge for breeding and utilization of the species. Allozyme markers were used to investigate the mating system of four populations of the species. All the populations had high outcrossing rates, with a mean multilocus outcrossing rate of 0.91. The implications of a highly outcrossed mating system to the utilization of A. saligna are discussed.

Mots clés

  • Acacia saligna
  • agroforestry
  • mating system
  • high outcrossing.
access type Accès libre

Genetics of Shrinkage in Juvenile Trees of Pinus radiata D. Don From Two Test Sites in Australia

Publié en ligne: 14 Oct 2017
Pages: 145 - 151

Résumé

Abstract

To examine the genetic control of wood shrinkage (radial, tangential and longitudinal) in juvenile wood of radiata pine (Pinus radiata D. Don), we assessed samples collected at breast height in two related progeny tests of age 8 and 9 years, established at two different sites in Australia. Green to oven-dry tangential and radial shrinkage for the outer-rings was similar at both sites. Similarly, mean longitudinal shrinkage for the outer-rings was similar at both sites (0.3%, ranging from 0.1 to 1.9 at Flynn and 0.4%, ranging from 0.02 to 1.6, at Kromelite). Mean longitudinal shrinkage for the inner-rings was 4 times greater than that of the outerrings at both sites. The magnitude of the gradient of longitudinal shrinkage from pith to bark (0.001 to 2.9%) is large enough to cause distortion problems including twist and warp, during drying of sawn boards. These values also suggest that shrinkage in the juvenile core of radiata pine is of major economic importance and therefore should be improved either through genetics or silviculture. Individual-tree narrow-sense individual heritability for tangential and radial shrinkage in the outer-rings (4-6) was moderate at Flynn (0.24 ± 0.09 and 0.26±0.07, respectively). There was a lack of significant genetic variation for longitudinal shrinkage in the outer-rings but significant genetic control for the inner-rings (1-2) (h2 = 0.26 ± 0.07). More samples per family are required to detect significant genetic variation for shrinkage traits than other traits due to higher background variation in sampling and measuring shrinkage traits relative to other wood quality traits such as density, microfibril angle (MfA), spiral grain and modulus of elasticity (MoE).

Mots clés

  • Pinus radiata
  • juvenile wood
  • distortion
  • shrinkage
  • genetic control
access type Accès libre

Molecular Cloning and Characterization of a cDNA Encoding Sedoheptulose-1,7-bisphosphatase from Mulberry (Morus alba var. multicaulis)

Publié en ligne: 14 Oct 2017
Pages: 152 - 157

Résumé

Abstract

A full-length cDNA encoding sedoheptulose-1,7-bisphosphatase (SBPase; EC 3.1.3.37) was cloned from mulberry (Morus alba var. multicaulis) by rapid amplification of cDNA ends (RACE). The cDNA consisted of 1,527 nucleotides with an open reading frame (ORF) of 1,179 nucleotides encoding a 393 amino acid protein of approximately 42.6 kDa. Sequence comparison analysis showed that mulberry SBPase (MSBPase) had high homology to other plant counterparts. Phylogenetic and molecular evolutionary analysis revealed that MSBPase fell into plant SBPase group. Moreover, SBPase and fructose-1,6-bisphosphatase (FBPase; EC 3.1.3.11) shared 28-32% identical residues, suggesting that the two enzymes originated from the same evolution branch. Molecular modeling indicated that each subunit of MSBPase was composed of α-helices and β-sheets joined by turns and loops, and folded into a structure of hexahedron shape which was very similar to FBPase.

Mots clés

  • sedoheptulose-1,7-bisphosphatase
  • fructose-1,6-bisphosphatase
  • cDNA cloning
  • mulberry
access type Accès libre

Genetic Diversity and Population Structure of Apricot (Prunus armeniaca L.) from Northern Pakistan using Simple Sequence Repeats

Publié en ligne: 14 Oct 2017
Pages: 157 - 164

Résumé

Abstract

A collection of 44 P. armeniaca accessions and three related species, from diverse geographic areas, covering the entire Northern hemisphere with emphasis on Pakistani apricots, was screened with 10 SSR primer pairs developed in apricot, to characterize the cultivars and establish their genetic relationship. Given the fact that the Central Asian region is considered a center of origin of apricot, particular attention was devoted to accessions from the Hunza region of Pakistan. The primers correctly amplified a repeatable polymorphic pattern, which unequivocally distinguished all genotypes under study. Altogether 123 alleles were identified with an average of 12.30 alleles per locus. The observed heterozygosity for individual loci ranged from 0.28 to 0.77 with an average of 0.64. A neighbour joining method identified four groups from: (A) Central Asia, (B) Irano-Caucasia, (C) Continental Europe and (D) North America. The dendrogram confirms the historic dissemination pathways of apricot from its centre of origin in Asia to the West. Apricot cultivars from the Hunza region (Northern Pakistan) revealed a high variability, as genetic diversity is still conserved due to the traditional practice of planting seeds from the best trees.

Mots clés

  • Genetic variation
  • microsatellites
  • eco-geographic groups
  • Hunza
  • center of origin
access type Accès libre

Genetic Variation in Frost Damage and Seed Zone Delineation within an Altitudinal Transect of Pinus devoniana (P. michoacana) in Mexico

Publié en ligne: 14 Oct 2017
Pages: 165 - 170

Résumé

Abstract

We explored the patterning of genetic variation among Pinus devoniana Lindl. (also known as P. michoacana Martínez) populations to develop guidelines for seed and seedling movements, intended for improving the matching between genotypes and environments regarding frost tolerance, in reforestation programs. Open-pollinated seed from 16 populations along an altitudinal transect (1600 to 2450 m) were collected near Morelia, State of Michoacán, México. A common-garden provenance test, established with 2.5-year-old seedlings, was assessed for frost resistance conducting a laboratory frost damage test (-9°C). Results indicate that there were significant differences among provenances (P = 0.0261) for frost damage. Variation among provenances was structured as an altitudinal cline, with populations from lower altitudes being the least tolerant to frost. Linear regression statistics suggest that for each increment of 100 m of provenance altitude, there will be a 5.2% decrease in frost damage. We suggest the use of two provisional altitudinal seed zones of 400 m breadth each (lower and upper limits for zone 1: 1600 m and 2000 m of altitude; for zone 2: 2000 and 2400 m, respectively), and for reforestation of a given site, the use of seedlings originated from seed of the same seed zone or within ±200 m of altitude from the elevation of the reforestation site.

Mots clés

  • Pinus devoniana
  • Pinus michoacana
  • altitudinal genetic variation
  • provenances
  • frost damage
  • frost hardiness
  • seed zoning
  • seed and seendling movement guidelines
access type Accès libre

Evaluation of Provenances of Eucalyptus camaldulensis and Clones of E. camaldulensis and E. tereticornis at Contrasting Sites in Southern India

Publié en ligne: 14 Oct 2017
Pages: 170 - 179

Résumé

Abstract

A total of 188 open-pollinated families of Eucalyptus camaldulensis Dehnh. from 18 Australian natural provenances and 15 selected Indian families of the “Mysore Gum” land race were evaluated in three provenance- family trials at contrasting sites in southern India. At two years of age, the fastest growth was recorded at the driest site in Tamil Nadu, where E. camaldulensis provenances from Queensland were superior to those from Northern Territory and Western Australia, and the Indian land race. Provenance differences were less pronounced at the two higher-rainfall sites in Andhra Pradesh and Kerala. Interaction of provenance performance with site was significant. Within- provenance individual-tree heritabilities for height and diameter at breast height (dbh) were low at the three individual sites, ranging from 0.08 ± 0.05 to 0.19 ± 0.05 for height and 0.10 ± 0.05 to 0.19 ± 0.04 for dbh. Across-site heritabilities, 0.07 ± 0.02 for both height and dbh, were lower than those at individual sites. Phenotypically superior trees were selected from these trials and seven other plantings of E. camaldulensis and Eucalyptus tereticornis Smith in southern India and cloned from basal coppice. A total of 78 E. camaldulensis and 27 E. tereticornis selections, together with thirteen commercially planted Eucalyptus clones and five superior natural provenance seedlots, were tested in clonal trials at three sites in southern India, the different individual treatments being tested at from one to three sites. Three years after planting, most clones selected from E. camaldulensis trials and the commercial Eucalyptus clones were superior in volume production to E. tereticornis clones and seedling controls at a dry site in Tamil Nadu. A smaller number of clones, particularly those of E. camaldulensis, were also superior to seedling controls at an intermediate-rainfall site in Andhra Pradesh. At a third high-rainfall site in Kerala, seedling controls were superior to all but four of 46 clones tested. Significant clone-by-site interaction was observed for growth traits. At the dry site in Tamil Nadu, clones varied widely in their wood basic density from 450 to 700 kg m-3, and there was no significant correlation of clonal values for growth and wood density. The results confirm that clones are best selected and tested in environments similar to those where they will be deployed.

Mots clés

  • Eucalyptus camaldulensis
  • E. tereticornis
  • clone
  • provenance trial
  • deployment
  • genotype-by-environment interaction
access type Accès libre

Short Note: Coefficients of Variation in Variables with Bounded Scales

Publié en ligne: 14 Oct 2017
Pages: 179 - 180

Résumé

Abstract

With a variable that is recorded on a scale with fixed bounds, it can be appropriate to use for the denominator of the coefficient of variation the square root of the (sign-independent) product of the differences between the mean and the two bounds of the scale. A simple illustrative example is given.

Mots clés

  • coefficient of variation
  • subjective rating
  • subjective score
  • binary variables
access type Accès libre

Genetic Variation in an International Provenance-Progeny Test of Pinus caribaea Mor. var. bahamensis Bar. et Gol., in São Paulo, Brazil

Publié en ligne: 14 Oct 2017
Pages: 181 - 187

Résumé

Abstract

A combined provenance-progeny test of Pinus caribaea var. bahamensis was established in Paraguaçu Paulista Experimental Station, São Paulo State, Brazil, in a “compact family” blocks design with 14 provenances, 2 to 10 families per provenance, 5 individuals per subplot, and 7 replications. Variation among and within island, provenances and families and genetic parameters for d.b.h., height, and real volume were investigated, about 15 years after planting. Analysis of variation for all studied traits revealed significant differences among islands, provenances within island and families within islands, suggesting the possibility of increasing the timber yield through selection of the more productive provenances and families within the best island. Genetic correlations on growth traits were high and statistically significant, indicating that substantial gains could be made through indirect selection for one trait based on direct selection for another. Norman Castle provenance from Abaco Island performed best for d.b.h. height and volume, while San Andros and Little Harbour Cay, both from Andros Island performed worst for d.b.h. and height, respectively, and South Riding from Grand Bahamas Island performed worst for volume. The best provenance growth compared to that P. elliottii var. elliottii species at the same experimental site suggests that P. caribaea var. bahamensis has high silvicultural potential for the Paraguaçu Paulista region.

Mots clés

  • Pinus caribaea
  • provenance-progeny test
  • genetic variation
  • genetic parameters
  • quantitative traits
access type Accès libre

Short Note: Root Restriction Hindered Early Allometric Differentiation Between Seedlings of Two Provenances of Canary Island Pine

Publié en ligne: 14 Oct 2017
Pages: 187 - 193

Résumé

Abstract

Based on the optimal partitioning theory, the comparative assessment of seedling allometry is a common task in retrospective genetic tests and early testing of forest reproductive material. Our hypothesis was that root restriction imposed by the container might hinder or rule out genetic differences in biomass allocation. We grew seedlings of two contrasted provenances of Canary Islands pine in mini-rhizotrons, 60 and 90 cm deep, and alternatively in standard bottom-open 200 cc forest containers. In the mini-rhizotrons, plants from the drier provenance allocated more biomass to roots, especially to the tap root and invested less in needles, both in a biomass and leaf area basis, and this morphological divergence increased between two harvests, undertaken at 57 and 115 days after planting. By contrast, confirming our hypothesis, at the 115 days harvest, the plants grown in standard containers did not exhibited significant differences between provenances for Leaf Mass Fraction, Root Mass Fraction and Leaf Area Ratio. We conclude that the physical constraint for root development imposed by small containers increases the probability of dismissing the genetic effect in biomass allocation when assessing forest reproductive materials at the short term, even when the whole plant growth (total dry weight) might be unaffected.

Mots clés

  • Mini-rhizotrons
  • root architecture
  • container
  • biomass allocation
  • ontogeny
access type Accès libre

Spatial Genetic Structure Within Two Contrasting Stands of Scots Pine (Pinus sylvestris L.)

Publié en ligne: 14 Oct 2017
Pages: 193 - 202

Résumé

Abstract

When considering neutral nuclear markers, genetic differentiation of Scots pine (Pinus sylvestris L.) populations is known to be low. The homogeneity arises particularly as an effect of common ancestry in a recent evolutionary history as well as an extensive gene flow, especially through pollen. However, within populations several other forces may shape the spatial distribution of genetic variation, including establishment history, environmental and silvicultural selection. These local forces are known to produce non-random spatial patterns of genetic variation, however little is known on fine-scale spatial genetic structure of Scots pine. In this study, two stands of this species with different establishment histories, selected within one larger population located in northern Poland were genotyped and analysed for genetic variation and within-stand spatial genetic structure. Results revealed no differences in genetic variation, although stands are separated about 60 km, suggesting that the two populations share a common genetic pool. The spatial genetic structure in both stands was found to be slightly different and was attributed to differences in the mode of populations’ establishments. Finally, results confirmed that gene flow in Scots pine is extensive, causing genetic homogeneity within a single population.

Mots clés

  • genetic structure
  • spatial autocorrelation
  • relatedness coefficient
  • forest management
  • colonization
  • Scots pine
access type Accès libre

Inbreeding Depression in the Full-sib Offspring of Populus nigra L.

Publié en ligne: 14 Oct 2017
Pages: 202 - 210

Résumé

Abstract

Controlled pollination was carried out in the species Populus nigra L. in a greenhouse on isolated branches between sisters and a brother - inbreeding (S x B). Female trees (sisters) were also exposed to open pollination (OP) in the neighbourhood of a male tree (brother) and other Populus nigra trees in the vicinity. The analysis of 11 microsatellites was done in the offspring from the inbreeding (S x B) and from the OP. In OP offspring was found 20-76% of viable individuals that were coming from pollination with brother’s pollen (spontaneous inbreeding). These individuals were separated from the offspring. In a randomised field trial the offspring were evaluated for two years. Fitness decreased in S x B offspring, traits of plant height, trunk diameter, height increment and resistance to Melampsora larici-populina Kleb. were lower in comparison with those of OP offspring. A coefficient of inbreeding depression (δ) ranged from 0.373 to 0.034. The significance of differences between the offspring from S x B and OP of the particular sisters was proved. About 30% of homozygous microsatellite loci were identified in inbred S x B offspring, which was more than in OP offspring. This difference was significant in the offspring of three sisters; it was not significant in the offspring of one sister. This trend corresponded to the results of growth traits.

Mots clés

  • inbreeding depression
  • open pollination
  • spontaneous inbreeding
  • microsatellites
  • Populus nigra L.
access type Accès libre

Short Note: The Genetic Correlation Between Air-dried Density and Basic Density in Eucalyptus Nitens Wood Cores

Publié en ligne: 14 Oct 2017
Pages: 210 - 212

Résumé

Abstract

Cores extracted from trees to assess wood chemistry are generally not used to assess basic density in eucalypt pulpwood breeding programmes, as the measurement of basic density requires high temperature drying. However, both wood chemistry and air-dried density can be assessed on the same core. This study found that the inter-trait genetic correlation between core air-dried and basic density to be effectively equal to one in two Tasmanian Eucalyptus nitens progeny trials. This implies that selection for basic density could be undertaken using air-dried density with little or no reduction in genetic gain, thus negating the need to extract a separate core to assess basic density and wood chemistry. The adoption of this practice could considerably reduce the cost of assessing these traits in eucalypt breeding programmes.

Mots clés

  • Eucalyptus nitens
  • selection trait
  • non-destructive assessment
  • air-dried density
  • basic density
  • wood chemistry
  • pulp yield
  • cellulose content
  • near infrared spectroscopy (NIR)
  • genetic correlation
access type Accès libre

Heterogeneity and Spatial Autocorrelation for Chloroplast Haplotypes in Three Old Growth Populations of Northern Red Oak

Publié en ligne: 14 Oct 2017
Pages: 212 - 220

Résumé

Abstract

In eastern North America, evidence for cryptic northern refugia could contribute to resolving Reid’s Paradox, the disparity between the rate of oak recolonization indicated by pollen deposition and the rate indicated by contemporary seed dispersal studies. Severe anthropogenic disturbance of oak-dominated forests throughout eastern North America followed by regeneration from isolated patches and deliberate planting in some regions could obscure the signal of discontinuity expected from small, cryptic refugia. In this study of northern red oak, Quercus rubra L., the dominant representative of Quercus section Lobatae in the eastern United States, we address the question of appropriate sample size for accurate detection of the biogeographical distribution of chloroplast haplotype diversity in Q. rubra. We examined chloroplast DNA (cpDNA) variation in all Q. rubra over 17 cm in diameter (310 trees) in three forest fragments with documented histories of minimal disturbance for the last 100-190 years. cpDNA polymorphisms in three intergenic regions revealed different haplotype frequencies between the two local fragments located within 1 km of each other and complete discontinuity for the predominant haplotype between these two sites and a site 207 km distant. Haplotypes displayed positive spatial autocorrelation over 10-40 meter distances. Sample sizes of 10 or fewer taken at 50 meter intervals along a linear transect yielded poor estimates of haplotype frequencies and did not accurately detect haplotype richness.

Mots clés

  • cpDNA
  • Quercus rubra
  • chloroplast
  • genetic diversity
  • patch size
  • postglacial migration
access type Accès libre

The Needle Volatile Composition of Pinus nigra J. F. Arnold, P. sylvestris L., P. densiflora Siebold et Zucc. and P. thunbergiana Franco Trispecies Hybrids

Publié en ligne: 14 Oct 2017
Pages: 221 - 226

Résumé

Abstract

The needle volatile composition of two trispecies hard pine hybrids produced by the controlled hybridization and their parents was researched with gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) in order to confirm their hybridity. The analysed trispecies hybrids were: (Pinus nigra x P. sylvestris) x P. densiflora (= nisyde) and (P. nigra x P. sylvestris) x P. thunbergiana (= nisyth). A total of 59 compounds was identified. All identified compounds were terpenes, except one. The trispecies hybrids showed the same qualitative pattern of the needle volatile composition as their parental species. However, there were quantitative differences in several major terpenes. According to the needle volatile composition the hybrids nisyde were more similar to the female parent, whereas the hybrids nisyth were more similar to the male parent. The hybrids nisyth had a considerably higher content of β-pinene (specific component of P. thunbergiana) than the other analyzed groups. The content of thunbergol (specific component of P. densiflora) in the hybrids nisyde was not considerably different in relation to the other groups. The intermediary quality of the hybrids nisyde and nisyth for most components in relation to their parents, as well as the previous morphometric analysis, confirms their hybrid character.

Mots clés

  • trispecies hybrids
  • (Pinus nigra x P. sylvestris) x P. densiflora
  • (Pinus nigra x P. sylvestris) x P. thunbergiana
  • needle volatiles
  • GC
  • GC/MS
access type Accès libre

The Chloroplast DNA Polymorphisms of White Oaks of Section Quercus in The Central Balkans

Publié en ligne: 14 Oct 2017
Pages: 227 - 234

Résumé

Abstract

A total of 444 oak trees from 110 populations from a previously under-sampled area in the central Balkans were analysed using four primer/enzyme combinations which amplified and restricted four, largely non-coding regions of the maternally inherited chloroplast DNA. Using the nomenclature of PETIT et al. (2002 a) to classify the haplotypes and lineages, the seven haplotypes that were found in Croatia, Bosnia and Herzegovina, Montenegro, Albania, Macedonia and southern Kosovo consisted of haplotypes 2, 4, 5, 6, 7, 17, 31, as well as the subtypes of haplotypes 4 (a), 5 (a, b, c), and 17 (a). Five of these haplotypes belong to lineage A. One of these, haplotype 5, is present throughout the sampled area. The distributions of the other haplotypes from this lineage are more geographically structured. The other two haplotypes, haplotype 2 and haplotype 17, belong to lineages C and E, respectively. The data are combined with previous data by PETIT et al. (2002 b) to provide more detailed information of the postglacial routes of colonisation taken by oaks in south-eastern Europe.

Mots clés

  • cpDNA polymorphism
  • Quercus
  • central Balkans
  • colonisation
  • glacial refugia
  • haplotypes
access type Accès libre

Paxillus involutus Forms an Ectomycorrhizal Symbiosis and Enhances Survival of PtCOMT-modified Betula pendula in vitro

Publié en ligne: 14 Oct 2017
Pages: 235 - 242

Résumé

Abstract

The ability of the PtCOMT (caffeate/5-hydroxyferulate O-methyltransferase from Populus tremuloides L.) - modified Betula pendula Roth. lines to form symbiosis with an ectomycorrhizal (ECM) fungus Paxillus involutus Batsch Fr. was studied in vitro. Lignin precursor gene PtCOMT was introduced into two B. pendula clones under the control of the cauliflower mosaic virus 35S promoter or the promoter of the sunflower polyubiquitin gene UbB1. Of the four transgenic lines, one 35SPtCOMT line (23) had a decreased syringyl/guaiacyl (S/G) ratio of root lignin, and two UbB1-PtCOMT lines (110 and 130) retarded root growth compared to the control clone. Both control clones and all transgenic lines were able to form ECMs with P. involutus, but the transgenic lines differed from the controls in the characteristics of the ECMs. The number of lateral roots covered with fungal hyphae and/or development of a Hartig net (HN) were reduced in line 23 with a decreased S/G ratio, and in lines 110 and 130 with slower root formation and changed root morphology, respectively. However, line 23 benefited more from the inoculation in lateral root formation than the control, and in lines 110 and 130 the percentage of viable plants increased most due to inoculation. The results show that B. pendula plants genetically transformed with the lignin gene PtCOMT could form mycorrhizal symbiosis regardless of changes in either the root S/G ratio or development. The benefits of the symbiosis were variable even in the closed in vitro system, and dependent on the clone or transgenic line and the ECM fungal symbiont.

Mots clés

  • Betula pendula
  • COMT
  • ecological impacts of gmtrees
  • ectomycorrhiza
  • lignin modification
  • Paxillus involutus
access type Accès libre

Genetic Diversity of the Relict Plant Taiwania cryptomerioides Hayata (Cupressaceae) in Mainland China

Publié en ligne: 14 Oct 2017
Pages: 242 - 249

Résumé

Abstract

The genetic diversity and differentiation of five populations of Taiwania cryptomerioides Hayata in mainland China were investigated using inter-simple sequence repeats (ISSR). In comparison with other coniferous species, T. cryptomerioides from mainland China possesses little genetic variation, particularly at the level of individual populations (the percentage of polymorphic loci, Nei’s gene diversity and Shannon’s indices of diversity at the species and population levels are 38.02%, 0.1326, 0.1986 and 9.27%, 0.035, 0.0518 respectively). In contrast, the level of population differentiation is much higher (GST: 0.7269; Shannon’s genetic differentiation: 0.7392; Hickory è B: 0.668; AMOVA genetic differentiation: 72.37%). The genetic divergence of pairs of populations was not significantly correlated with the geographical distance separating them. Current patterns of genetic variation were related to biogeographic history and the small population size. On the basis of these findings, we discuss the development of conservation strategies for this endangered species.

Mots clés

  • Taiwania cryptomerioides
  • genetic diversity
  • ISSR
  • China
  • relict species
  • conservation
access type Accès libre

Genetic Variation Within Two Sympatric Spotted Gum Eucalypts Exceeds Between Taxa Variation

Publié en ligne: 14 Oct 2017
Pages: 249 - 256

Résumé

Abstract

Population substructure and hybridization, among other factors, have the potential to cause erroneous associations in linkage disequilibrium (LD) mapping. Two closely related spotted gum eucalypts, Corymbia variegata and C. henryi (Myrtaceae) occur in sympatry in the east coast of Australia and potentially interbreed. They are morphologically similar but are distinguished as separate species based on capsule and foliage size. To determine whether they hybridize in nature and its implications for LD mapping, we investigated the level of molecular divergence between the two species at two sympatric locations separated by 300 kilometres. Very few individuals of intermediate morphology were identified, despite the two species occurring only metres apart. Analysis of genetic structure using 12 microsatellite loci showed that genetic differentiation between populations of the same species at different locations (FST = 0.07 for both species; p = 0.0001) was significantly higher than that observed between species at each location (mean FST = 0.02 and 0.04 for Cherry tree and Bunyaville respectively; p = 0.0001; all Mann-Whitney U-test p ≤ 0.01). No species-specific alleles or significant allele frequency differences were detected within a site, suggesting recurr#ent local gene flow between the two species. The lack of significant allele frequency differences implies no population stratification along taxonomic lines. This suggested that there is little concern for cryptic hybridization when sampling from sites of sympatry for LD mapping.

Mots clés

  • panmixia
  • hybridization
  • gene flow
  • association mapping
  • population structure
  • admixture
  • reproductive isolation
  • linkage disequilibrium
access type Accès libre

Pollen Dispersal and Its Spatial Distribution in a Seed Orchard of Larix kaempferi (Lamb.) Carr.

Publié en ligne: 14 Oct 2017
Pages: 256 - 261

Résumé

Abstract

Pollen dispersal and its spatial distribution in a seed orchard of Larix kaempferi in Changlinggang, Jianshi, Hubei Province has been studied for 3 years. The results show that pollen dispersal is directly affected by weather conditions, with wind speed being the main factor controlling pollen dispersal. Pollen dispersal follows a date rhythm of low-high-low during the whole pollen dispersal season with a peak date for 3-5 days, and a time rhythm of low-high-low with the peak time at 10:00-16:00 during the day. For pollen density in the air there are significant differences among dates, and among different day times during dispersing. There are no significant differences between pollen densities in space with regard to horizontal directions, 8 orientations, and different positions in the tree crown in this seed orchard, in all of these cases pollens are evenly distributed. There are significant differences for pollen densities among different vertical heights, showing a cluster distribution type. The pollination level in this seed orchard is very low and needs a supplement mass pollination (SMP).

Mots clés

  • Larix kaempferi (Lamb.) Carr
  • seed orchard
  • pollen dispersal
  • spatial distribution
  • pollination level.
access type Accès libre

Discrimination between seedlings of Eucalyptus globulus, E. nitens and their F1 hybrid using near-infrared reflectance spectroscopy and foliar oil content

Publié en ligne: 14 Oct 2017
Pages: 262 - 269

Résumé

Mots clés

  • eucalypt
  • spectra
  • 1,8-cineole
  • NIRS
  • fresh leaves
  • discriminant analysis
  • partial least-squares regression
access type Accès libre

Genetic Parameters of Somatic Clones of Coastal Douglas-fir at 5½-Years across Washington and Oregon, USA

Publié en ligne: 14 Oct 2017
Pages: 269 - 275

Résumé

Abstract

Five genetic tests involving 70 somatic clones of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were planted March-April 1999 in Weyerhaeuser plantations across western Washington and Oregon states, USA. Four of the tests are in Longview and Twin Harbors regions of Washington, and one test is in Springfield, Oregon. Each test is based on single-tree plots with 12 randomized complete-blocks. The 70 coastal Douglas-fir clones were propagated by somatic embryogenesis from two full-sib families that had the same female parent. Results are reported for survival, height, diameter at breast-height (DBH) and volume growth at 5½-years. These tests provide evidence of acceptable growth and survival of somatic trees of coastal Douglas-fir across a range of site conditions. Height had a clonal heritability of 0.25 ± 0.01, DBH 0.21 ± 0.01 and volume 0.20 ± 0.01. The growth traits were all strongly genetically associated with clonal correlations of 0.92 to 0.99. Clonal performance for growth proved quite stable across tests with an overall between-test correlation of 0.84 ± 0.04. There was little variance due to clone x test interactions.

Mots clés

  • Coastal Douglas-fir
  • somatic embryogenesis
  • adaptability
  • clonal heritabilities
  • clonal stability
access type Accès libre

Height–Diameter Relationships for Jack Pine Seedlots of Different Genetic Improvement Levels

Publié en ligne: 14 Oct 2017
Pages: 276 - 282

Résumé

Abstract

Differences in height-diameter (H-DBH) relationship were investigated using the Chapman-Richards function among jack pine seedlots planted in a realized genetic gain test in New Brunswick. Three seedlots representing the bulk mixed cone collection from the 1979 J.D. Irving’s first-generation seedling seed orchard (JDISSO) before rogueing (UNR), after the first time genetic rogueing (1STR) and after the second time genetic rogueing (2NDR), respectively, were planted in the test. Unimproved commercial seedlots (UC) were also included for comparison. Results indicate that an overall H-DBH relationship for all the seedlots was not appropriate. Seedlot pairwise comparisons in H-DBH relationships showed that, whereas most seedlot pairs were significantly different from each other, there was no significant difference between the UNR and UC and between the 1STR and 2NDR. Two models were developed with one targeting the UNR and UC (UNIMPROVED) and the other targeting the 1STR and 2NDR (IMPROVED). The difference between the UNIMPROVED and IMPROVED models was caused only by asymptote of the Chapman-Richards function. Applying the UNIMPROVED or IMPROVED model to predict height of the 1STR and 2NDR or the UNR and UC would result in an under-estimated or an over-estimated bias by 2 to 3% in height. In light of this study, seedlot differences in H-DBH relationships should be integrated into growth and yield models by a multiplier for height depending on genetic improvement levels.

Mots clés

  • Pinus banksiana
  • tree improvement
  • realized gain test
  • Chapman-Richards function
  • extra sum of squares method
  • growth and yield.
access type Accès libre

A Strategy for the Second Breeding Cycle of Larix x marschlinsii in Québec, Canada Including Experiments to Guide Interspecific Tree Breeding Programme

Publié en ligne: 14 Oct 2017
Pages: 282 - 291

Résumé

Abstract

A strategy for the genetic improvement of Larix decidua P. Mill., L. kaempferi (Lamb.) Carrière and their hybrid (L. x marschlinsii Coaz) in Québec, Canada, was set up to provide short and long-term genetic gains, as well as basic populations for some fundamental experiments. A reciprocal recurrent selection with forward selection strategy (RRS-FS) will be applied by using a pollen mix breeding with a partial population paternity analysis (PMX/WPPA). The genetic mechanisms responsible for heterosis among trees remain poorly understood. This complicates the implementation of multi-species genetic improvement programmes seeking to achieve the full benefits of interspecific hybridization. Various strategies to exploit heterosis are outlined. To expand our knowledge and guide our future choices, basic research has been integrated directly into breeding and testing activities, as well as through experiments integrated within activities leading to recommendations about the top-ranked families to be used in reforestation (cuttings). These experiments can also serve as the basis for future studies seeking a better understanding of heterosis through molecular genetics.

Mots clés

  • paternity analysis
  • heterosis
  • interspecies hybrid
  • interspecific breeding strategy
  • polymix crossing
  • Larix x eurolepis
access type Accès libre

Low Chloroplast DNA Diversity in Red Dogwood (Cornus sanguinea L.)

Publié en ligne: 14 Oct 2017
Pages: 291 - 300

Résumé

Abstract

The red dogwood Cornus sanguinea L. is a deciduous shrub of the temperate and Mediterranean zones. It is often used in landscape gardening for miscellaneous purposes. Chloroplast DNA markers, the so-called cpDNA haplotypes, are a very potential marker type to characterise the large scale variation pattern within the natural range of a species. In this study, a total of 86 populations and 673 individuals were sampled all over Europe. Eight different haplotypes were recognised by combinations of several PCR-RFLP patterns. They are divided into 3 groups of related types. There is no association between these 3 groups and their geographic occurrence within the tested material. One haplotype strongly dominates in the whole distribution area. It takes nearly 90 percent whereas the remaining seven haplotypes together reach to approximately 10 percent. Besides the low number of haplotypes, the total genetic variation HT = 0.15 is much lower in Cornus sanguinea compared to other European tree and shrub species. Despite the low level of variation, several cases of introduced populations could be detected. Other haplotypes than the common type are found only in narrow areas. This result indicates that after the colonisation of the European continent only a very restricted gene flow could have taken place.

Mots clés

  • Cornus sanguinea L.
  • red dogwood
  • genetic variation
  • chloroplast DNA
  • PCR-RFLP
  • haplotypes
  • gene flow
  • distribution area
  • introduced populations.
access type Accès libre

Comparative Meiotic Chromosome Studies in Nine Accessions of Tecomella undulata (Sm.) Seem., Threatened Tree of Indian Desert

Publié en ligne: 14 Oct 2017
Pages: 301 - 306

Résumé

Abstract

Meiotic studies were carried out in nine different accessions of T. undulata collected from three districts of Rajasthan, India. Data collected on chromosome associations, chiasma frequency and their distribution pattern concluded that the somatic chromosome number of T. undulata is 2n = 2x = 36 which is at variance with published literature. The high frequency of 18:18 chromosome distribution at anaphase I and an overwhelming percentage of stainable pollens observed are indicative of overall genomic stability as supported by complete absence of accessory chromosomes (B) and supernumerary nucleoli. Numerical alteration of chromosomes might have played an important role in origin and adaptation of T. undulata to the adverse climate conditions of Indian desert.

Mots clés

  • genetic variation
  • meiotic studies
  • threatened tree
  • Tecomella undulata
  • Bignoniaceae
access type Accès libre

Genotype by Environment Interaction in Pinus sylvestris L. in Southern Sweden

Publié en ligne: 14 Oct 2017
Pages: 306 - 311

Résumé

Abstract

To estimate the amount of genotype by environment interaction (G x E) data was obtained within the Swedish breeding program of Pinus sylvestris L. The calculations were based on estimates of G x E expressed by the genetic correlations across trials. In total, 66 progeny trials were included coming from 17 different test series. The number of parents tested per progeny trial was in average 52. Some parents were tested in several series and in total 812 parents were represented in the study. The results of our study showed that the amount of G x E for growth traits in Pinus sylvestris in southern Sweden was low. The median genetic correlation across trials for height, height increment and diameter were in the range 0.75-0.80 and the pattern of interaction was largely unpredictable from site differences in site index, latitude, longitude and altitude.

Mots clés

  • Scots pine
  • genetic correlation
  • stability
  • progeny testing
access type Accès libre

Genetic Variation in Resistance Against Heterobasidion annosum (Fr.) Bref. in Picea abies (L.) Karst. Expressed After Inoculation of Neighboring Stumps

Publié en ligne: 14 Oct 2017
Pages: 312 - 324

Résumé

Abstract

Based on the well-established knowledge that important spread of H. annosum is performed through spore infection of stumps and subsequent spread of mycelium to neighboring trees at points of root contact, an inoculation experiment was established in three adjacent fully pedigreed 17-year old Norway spruce field trials. In June 1995, every third row was cut and stump-inoculated with conidia belonging to the two contrasting types, P and S. 5 years later the remaining trees were evaluated by clear-cutting and mapping of rot occurrence. 34% of the trees were attacked. For each host-tree, the most likely source of infestation (i.e. possible inoculated donor-stump 5 years earlier) was evaluated based on orientation of the rot on the stump surface supplemented with samples of re-isolation of H. annosum of the two types. According to these estimates, the tested S-type turned out to be more aggressive towards Norway spruce than the tested P-type. Genetic variation in resistance was most convincingly detected in the most informative trial F175B. The pattern of genetic variation in the two roles as donor and host seems to differ. However, genetic variation was also expressed as general resistance, which is defined as the combined effect of donor stump, living host and across the two tested types of H. annosum. No indication of host x pathogen interaction was detected. This evidence combined with the general experience that resistance against root rot pathogens usually is partial and based on the cumulative effects of several genes, suggests that sustainable genetic gains in relative resistance may be obtainable in breeding programs of Norway spruce. The developed experimental set-up represents a useful concept for screening existing genetic trials for field resistance within a time scale of 5-6 years.

Mots clés

  • Heterobasidion annosum
  • Picea abies
  • genetic variation
  • resistance
  • stump inoculation
access type Accès libre

Microsatellites Reveal Clonal Growth and Genetically Distinct Groups in Cryptocarya chinensis in Fragmented Lower Subtropical Forest, China

Publié en ligne: 14 Oct 2017
Pages: 324 - 332

Résumé

Abstract

The lower subtropical monsoon evergreen broadleaved forest in South China (about 22° ~ 24° N) has a high conservation status, because of its uniqueness and high biodiversity. During the last few decades, most of these forests have been destroyed, and the remaining are being degraded by fragmentation. However, genetic information concerning the effects of fragmentation is currently lacking for plant species in these forests. In this study, therefore, eight microsatellites were used to study six Cryptocaya chinensis fragmented populations in Guangdong Province South China, and the results revealed a complex pattern of genetic variation within and among C. chinensis populations. Firstly, genetic variations demonstrate hitherto undetected clonal growth in C. chinensis. Secondly, current population structure of C. chinensis reflects an interaction between ancient homogeneous level of genetic variation and contemporary bottleneck via fragmentation. Small populations maintain substantial genetic variation of the initial populations through clonal growth, and do not show genetic depauperation compared to larger populations. Finally, two genetically distinct groups (West and Middle- East groups) are found in this area, connected by highly mixed contact zone.

Mots clés

  • clonal growth
  • Cryptocarya chinensis
  • habitat fragmentation
  • microsatellite
  • genetically distinct groups
  • contact zone
  • genetic diversity
access type Accès libre

Genetic Differentiation of Jack Pine (Pinus banksiana) and Red Pine (P. resinosa) Populations From Metal Contaminated Areas in Northern Ontario (Canada) Using ISSR Markers

Publié en ligne: 14 Oct 2017
Pages: 333 - 340

Résumé

Abstract

Metal accumulation in soil and plant tissues has caused severe ecological damage in forest ecosystems in the Sudbury region. The main objective of the present study was to determine the levels of genetic diversity in jack and red pine populations growing in metal contaminated and uncontaminated areas. Newly introduced populations were compared to 40 to 60 old populations. For jack pine, the percentage of polymorphic loci (P %) ranged from 14.6% to 45.8% with a mean of 31.6%. Nei’s gene diversity (h) varied from 0.046 to 0.169 with an average of 0.100, and Shannon’s index (I) ranged from 0.070 to 0.250 with an average of 0.153. The level of genetic variation was much lower in the red pine populations. For this species, the level of polymorphic loci varied from 4.55% to 27.27%. The mean for Nei’s gene diversity and Shannon’s information index, were 0.034 and 0.053, respectively. The highest genetic diversity values were observed in new plantations being developed by the Sudbury reforestation program. Overall, the genetic distance among the Pinus banksiana populations revealed that all the populations analyzed were genetically close to each other. There was no association between metal accumulation and genetic diversity for both species.

Mots clés

  • Jack pine
  • red pine
  • ISSR
  • genetic diversity
  • metal contamination
  • Sudbury
access type Accès libre

Genetic Variation in Early Growth Characteristics of Two Populations of Wild Service Tree (Sorbus torminalis (L.) Crantz) and Their Interrelationship

Publié en ligne: 14 Oct 2017
Pages: 340 - 348

Résumé

Abstract

This study was performed in order to compare two wild service tree populations (Sorbus torminalis (L.) Crantz) for their early growth and to find useful vegetative characteristics to be used in indirect selection of fast and tall growing trees of the species in the field. We used phenotypic and genotypic correlation coefficients estimated on data from 30 three-year old seedlings of each 40 randomly selected adult trees. Assuming genetic differences between the trees sampled, path analysis was performed on genotypic and phenotypic levels. Results showed that plus trees of one of the sites may be used for clonal seed orchard establishment. But the other site is suggested as a better site for breeding purposes with more effective Sorbus population. Collar diameter had the strongest positive direct effect and strongest correlation with plant height at the phenotypic level. In contrast, lateral branches showed very weak direct effect but relatively strong total indirect effect on plant height. Path analysis on the genotypic correlation coefficients detected negative indirect effect between the characters. Collar diameter could be regarded as a good predictor of plant height because of its strong direct and indirect phenotypic and genotypic correlations. The use of recommended selection criteria is discussed.

Mots clés

  • Genotypic correlation
  • Half-Sib progenies
  • Path analysis
  • Vegetative characteristics
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Genetic Variation in Two Rare Endemic Mexican Trees, Magnolia sharpii and Magnolia schiedeana

Publié en ligne: 14 Oct 2017
Pages: 348 - 356

Résumé

Abstract

Patterns of genetic variation were examined within two endemic tree species restricted to Mexican cloud forest, Magnolia sharpii and Magnolia schiedeana. Leaf samples collected from natural populations were analysed using PCR RFLP of cpDNA, Inter-SSR and isozyme genetic markers, which were used to test a series of hypotheses regarding patterns of intraspecific variation within the two species. Genetic diversity estimates derived from Inter-SSR markers (mean Spop of 0.56 and 0.50 for M. sharpii and M. schiedeana respectively) are comparable to values obtained for other tree species. As predicted on the basis of its larger geographic range, the degree of population differentiation was found to be higher within M. schiedeana than M. sharpii, with 12.9% and 3.4% of total variation recorded between populations for the two species respectively using isozymes, and 26% and 11% using Inter- SSR markers. Isozyme analyses indicated negative Fis values, which may be suggestive of inbreeding in populations of M. sharpii, but provided less evidence of inbreeding in M. schiedeana. On the basis of PCR RFLP analysis of cpDNA, two chloroplast types were differentiated, type A being recorded for all of the individuals of both species, with the exception of one population of M. schiedeana that was fixed for type B. These results are consistent with recent evidence suggesting that some endemic plant taxa are able to maintain relatively high diversity within populations despite the occurrence of inbreeding and genetic drift, and that species with wider geographic ranges tend to exhibit relatively high genetic differentiation among populations. Conservation strategies for these species need to take into account the significant genetic differences recorded among the populations studied.

Mots clés

  • cloud forest
  • conservation biology
  • genetic variation
  • isozyme
  • cpDNA
  • PCR-RFLP
  • Magnolia sharpii
  • Magnolia schiedeana
access type Accès libre

The Effect of Altitude on the Pattern of Gene Flow in the Endemic Canary Island Pine, Pinus canariensis

Publié en ligne: 14 Oct 2017
Pages: 357 - 363

Résumé

Abstract

Pinus canariensis is endemic to the western Canary Islands (NW coast of Africa), where it forms forest spanning an altitude from 500 to 2500 m. There are dramatic changes in environmental conditions (temperature, moisture and solar radiation) over short distances due to this elevation gradient in the Canary Island pine forest. Those differences in environmental conditions may lead to asynchronous flowering times among elevations. In this study we used nuclear and chloroplast microsatellites to characterize the genetic structure of two altitudinal transects on the southern slopes of Tenerife Island to test for genetic isolation among altitudes. Although significant differentiation among sites was detected, this differentiation was very low (FST = 0.013 with chloroplast markers, FST= 0.019 with nuclear markers) and appeared to be unrelated to altitude. The contrasting results between nuclear and chloroplast markers are also discussed in terms of statistical accuracy of markers and genome inheritance.

Mots clés

  • chloroplast microsatellites
  • nuclear microsatellites
  • population differentiation
  • isolation by altitude
52 Articles
access type Accès libre

Genetic Variation of Anatolian Black Pine (Pinus nigra Arnold. subsp. pallasiana (Lamb.) Holmboe) in the Lakes District of Turkey

Publié en ligne: 14 Oct 2017
Pages: 1 - 5

Résumé

Abstract

In this study, morphological characteristics of juvenile 1- and 2-year-old seedlings of Anatolian black pine were studied to estimate the amount of genetic variation and heritability of seedling traits of the species in the Lakes District of Turkey. This nursery study involved 460 parent trees from 23 populations in a randomized complete block design. Traits studied were the number and length of cotyledons, hypocotyls and epicotyls lengths, weight and length of initial roots, height, root collar diameter, and stem and root fresh weights, and number of buds. Variation was higher among than within populations with individual tree heritability ranging from 0.09 to 0.76, whereas family mean heritability ranged from 0.16 to 0.80. Genetic and phenotypic correlations between juvenile and 1-year-old seedling traits were generally the same sign and magnitude. Variation and heritabilities were higher for growth-related traits than the number and length of embryonic tissues. The observed level of population differentiation was low, possibly due limited geographic sampling of populations, which spanned only 2° of latitudes and longitudes, and 300m in elevation. If the observed heritabilities for growth traits were sustained to tree maturity combined family and within family selection would be effective in improving growth of this species in the Lakes District of Turkey. A broader geographic sampling is recommended for better estimation of population differentiation and establishment of the geographic pattern of the species in this region.

  • Keywords Pinus nigra
  • genetic variation
  • heritability
  • seedling traits
access type Accès libre

Chromosomal Mapping of 18S-25S and 5S Ribosomal Genes on 15 Species of Fagaceae From Northern Thailand

Publié en ligne: 14 Oct 2017
Pages: 5 - 13

Résumé

Abstract

Fifteen species of Fagaceae from Chiang Mai province, northern Thailand, were investigated: eight Castanopsis, four Lithocarpus and three Quercus species. The species were generally diploid with the chromosome number 2n = 24, and the basic number x =12 was confirmed in some species with meiosis. One tree belonging to Q. lenticellatus had 2n = 14. Chromosomal mapping of the highly repetitive 18S-25S and 5S ribosomal genes by fluorescence in situ hybridisation (FISH) was performed. Most species (from all three genera) showed four 18S-25S rDNA sites (two pairs: one subterminal major and one paracentromeric/intercalary minor loci) and two 5S rDNA sites (one pair: paracentromeric locus). Quercus kerrii also had two pairs of 18S-25S rDNA sites, but both were subterminal major loci. Two species, C. argentea and Q. brandisianus, only had one pair of 18S-25S rDNA sites. Two species, C. calathiformis and L. vestitus, showed an odd number of (unpaired) sites, and this indicated hybrid origin and/or polyploidy. Polyploid cells were detected in these species. The ribosomal gene maps based on both sequences together were genus-specific. In Castanopsis, the 18S-25S and the 5S genes were localized on three different chromosome pairs, and comprised species-specific maps. On the other hand, the ribosomal genes in Lithocarpus and Quercus were found only on two chromosome pairs, because one of the two 18S-25S rDNA loci was localized on the same chromosome as the 5S rDNA locus. The FISH markers may be used to clarify discrepancies arising from morphological assessments.

Mots clés

  • Fagaceae
  • Castanopsis
  • Lithocarpus
  • Quercus
  • fluorescence in situ hybridisation (FISH)
  • ribosomal gene mapping
  • 18S-25S and 5S rRNA genes
access type Accès libre

Evaluation of Early Rooting Traits of Eastern Cottonwood That Are Important For Selection Tests

Publié en ligne: 14 Oct 2017
Pages: 13 - 21

Résumé

Abstract

Vegetative propagation of superior genotypes via stem cuttings depends on their development of strong vigorous root system. Fourteen characters of cutting rooting were examined in multiannual tests with 12 genotypes of eastern cottonwood (Populus deltoides BARTR. EX MARSH) in course of evaluation of their utilization in selection tests. Variability and relationship among examined characters, and cutting survival rate were analyzed according to contribution of expected variances to the total variance and results of principal component analysis, stepwise regression analysis and path analysis. Along with total number and length of first-order roots, the characters that are regularly used in the assessment of rooting potential, our results signify dynamic shoot growth and uniform arrangement of roots on cutting at the beginning of growing period. The best results were obtained for shoot height at the second half of May. A rapid and non-destructive way of shoot characters’ measurement allows testing of larger material and prevents losses in propagation material of interesting genotypes. Alone or together with total root number and length these alternative characters could be used for the improvement of selection tests and procedures for cultivar technology design.

Mots clés

  • Populus deltoides
  • cutting rooting characters
  • cutting survival rate
  • multivariate analysis
access type Accès libre

An Evaluation of Selection for Volume Growth in Loblolly Pine

Publié en ligne: 14 Oct 2017
Pages: 22 - 28

Résumé

Abstract

Total inside-bark volume is the most important selection criterion for productivity in tree breeding programs in the Southeastern U.S. Tree breeders typically estimate total inside-bark volume based on outside-bark diameter at breast height and total height without accounting for stem taper or bark thickness. To make a direct determination of total inside- and outside-bark volume, a loblolly pine (Pinus taeda L.) open-pollinated family trial replicated with cultural treatments of weed control and fertilization was measured. This direct measurement was compared to typical volume estimates. In this trial, approximately 40 individuals from each of 25 open-pollinated first- and second-generation families were destructively sampled in the 13th growing season. Selection for volume using a combined-variable (diameter2 * height) equation was found to be highly effective for making volume gain. There was a high correlation between estimated and directly-measured total inside-bark volumes (0.99). Bark thickness and stem taper had low importance for stem volume selection. There was a positive genetic correlation between bark thickness and diameter at breast height (0.66). This indicates that selection for larger diameters may produce individuals with thicker bark, which may eventually affect total inside-bark volume estimates.

Mots clés

  • bark thickness
  • genotype by treatment interaction
  • stem taper
  • volume gain
  • Pinus taeda L.
  • stem volume
  • tree improvement
  • stem form
access type Accès libre

Genetic Diversity of Hippophae rhamnoides Populations at Varying Altitudes in the Wolong Natural Reserve of China as Revealed by ISSR Markers

Publié en ligne: 14 Oct 2017
Pages: 29 - 36

Résumé

Abstract

Hippophae rhamnoides L., a dioecious and deciduous shrub species, occupies a wide range of habitats in the Wolong Nature Reserve, Southwest China. Our present study investigated the pattern of genetic variation and differentiation among five natural populations of H. rhamnoides, occurring along an altitudinal gradient that varied from 1,800 to 3,400 m above sea level in the Wolong Natural Reserve, by using ISSR markers. Based on fingerprinting patterns generated by fifteen primers, high levels of genetic variation were present within populations and subpopulations. Substantial genetic divergence was observed among populations, and also among female and male subpopulations, the GST values equaling 0.182, 0.222, and 0.238, respectively. Such considerable divergence present among populations and subpopulations may be caused by complex topography which effectively restricts gene flow, and by variable climatic conditions at different altitudes which may cause varying selective pressures. A significantly positive correlation between genetic and altitudinal distances was detected for the five populations and female subpopulations of H. rhamnoides. The cluster analysis including all populations or male subpopulations resulted in three altitude groups. Our results suggest that altitudinal gradients may be the prime cause affecting the genetic variation pattern of different populations and subpopulations in H. rhamnoides in the Wolong Nature Reserve, Southwest China.

  • Keywords Altitudinal gradients
  • Genetic variation
  • Hippophae rhamnoides
  • ISSR markers
  • Sex-specific genetic differentiation
access type Accès libre

Triploid Induction in Populus alba x P. glandulosa by Chromosome Doubling of Female Gametes

Publié en ligne: 14 Oct 2017
Pages: 37 - 40

Résumé

Abstract

Efficient methods for obtaining unreduced female gametes are needed for triploid induction in Populus alba x P. glandulosa. A cytological study of MMCs and PMCs meiosis and staminate floral elongation revealed that there was a close association between MMCs meiotic stage and male bud phenology during development under the same environment conditions. Female buds of Populus alba x P. glandulosa were treated with 0.5% colchicine solution at the selected meiotic stages based on male bud phenology. The treated buds were pollinated with pollen of P. tomentosa. A high rate of unreduced female gametes occurred in late leptotene and pachytene stages of MMC, as evidenced by a relatively higher percentage of triploids in the progeny, when compared to progeny from colchincine application at other meiotic stages. The present results demonstrated that male bud phenology can be used to guide colchicine applications to female buds and cause a more efficient production of triploids.

Mots clés

  • chromosome doubling
  • effective treatment stage
  • female gamete
  • Populus alba x P. glandulosa
  • triploid
access type Accès libre

Short Note: Development of Mitochondrial Markers for Population Genetics of Norway Spruce [Picea abies (L.) Karst.]

Publié en ligne: 14 Oct 2017
Pages: 41 - 44

Résumé

Abstract

Norway spruce is an important commercial tree species in northern and central Europe. Pure mitochondrial DNA isolated from tissue culture materials grown in the dark were used to construct a partial mitochondrial library. 100 clones were randomly selected and 19 markers were isolated. Three of these markers proved to be polymorphic and two showed maternal inheritance in controlled crosses. These markers will be useful for population genetic studies in P. abies.

Mots clés

  • mtDNA
  • marker development
  • maternal inheritance
  • population genetics
  • length polymorphism
  • null alleles
  • Picea abies
access type Accès libre

Direct and Competition Additive Effects in Tree Breeding: Bayesian Estimation From an Individual Tree Mixed Model

Publié en ligne: 14 Oct 2017
Pages: 45 - 56

Résumé

Abstract

An individual tree model with additive direct and competition effects is introduced to account for competitive effects in forest genetics evaluation. The mixed linear model includes fixed effects as well as direct and competition breeding values plus permanent environmental effects. Competition effects, either additive or environmental, are identified in the phenotype of a competitor tree by means of ‘intensity of competition’ elements (IC), which are non-zero elements of the incidence matrix of the additive competition effects. The ICs are inverse function of the distance and the number of competing individuals, either row-column wise or diagonally. The ICs allow standardization of the variance of competition effects in the phenotypic variance of any individual tree, so that the model accounts for unequal number of neighbors. Expressions are obtained for the bias in estimating additive variance using the covariance between half-sibs, when ignoring competition effects for row-plot designs and for single-tree plot designs. A data set of loblolly pines on growth at breast height is used to estimate the additive variances of direct and competition effects, the covariance between both effects, and the variance of permanent environmental effects using a Bayesian method via Gibbs sampling and Restricted Maximum Likelihood procedures (REML) via the Expectation- Maximization (EM) algorithm. No problem of convergence was detected with the model and ICs used when compared to what has been reported in the animal breeding literature for such models. Posterior means (standard error) of the estimated parameters were σ̂2Ad = 12.553 (1.447), σ̂2Ac = 1.259 (0.259), σ̂AdAc = -3.126 (0.492), σ̂2 p = 1.186 (0.289), and σ̂2e = 5.819 (1.07). Leaving permanent environmental competition effects out of the model may bias the predictions of direct breeding values. Results suggest that selection for increasing direct growth while keeping a low level of competition is feasible.

Mots clés

  • competition effects
  • individual tree mixed model
  • additive and direct competition effects
  • estimation of additive (co)variances
  • Gibbs sampling
access type Accès libre

Inheritance and Genetic Gain in Wood Stiffness in Radiata Pine Assessed Acoustically in Young Standing Trees

Publié en ligne: 14 Oct 2017
Pages: 56 - 64

Résumé

Abstract

Wood stiffness, measured in terms of its modulus of elasticity (MoE) is an important characteristic of radiata pine for structural products. To select high stiffness radiata pine for breeding purpose, rapid, inexpensive methods for measuring wood stiffness are desirable. In this study, we explored acoustic instruments to measure stiffness of young standing trees in radiata pine and examined inheritance and genetic gain for stiffness in an Australian national breeding program. Time of flight of sound waves was recorded in standing trees in two progeny trials, one in eastern Victoria (Flynn) aged 8 years and the other in South Australia (Kromelite) aged 7 years. Average time of flight at Kromelite was higher than at Flynn, (519 μs/metre compared to 463 μs/metre) which corresponds to 3.7 GPa and 4.7 GPa for MoE, respectively. Heritability for time of flight was higher at Flynn (h2 = 0.67 ± 0.10) than at Kromelite (h2 = 0.30 ± 0.14). Selection of the best 10% for time of flight based on pooled data would result in 21% genetic gain in wood stiffness.

Mots clés

  • wood stiffness
  • acoustics
  • heritability
  • genetic gain
  • radiata pine
access type Accès libre

Construction of a Populus tremuloides Michx. BAC library

Publié en ligne: 14 Oct 2017
Pages: 65 - 69

Résumé

Abstract

We have constructed an aspen (Populus tremuloides Michx., line Turesson141) BAC library containing 55,296 clones in total. A random sampling of 86 BAC clones indicated an average insert size of 76 kb with a range of 20 to 160 kb. Twelve percent of the BAC clones in the library have an insert size larger than 100 kb. Based on an estimated genome size for Populus of 500 Mbp, library coverage is about 8 haploid genome equivalents. This library will be screened using AFLP marker identified before co-segregating with gender in a P. tremula x P. tremuloides progeny, where Turesson141 was the male parent.

Mots clés

  • Bacterial Artificial Chromosome
  • Populus
  • genome size
  • aspen
access type Accès libre

Crossing Success in Abies nordmanniana Following Artificial Pollination With a Pollen Mixture of A. nordmanniana and A. alba

Publié en ligne: 14 Oct 2017
Pages: 70 - 76

Résumé

Abstract

Controlled crossings were conducted with three Abies nordmanniana genotypes acting as mothers and a pollen mixture of three Abies nordmanniana genotypes and one Abies alba genotype acting as potential fathers. The aim was to investigate hybridization success under circumstances where pollen from both species are present, which is a potential risk in Danish clonal seed orchards of Abies nordmanniana. The number of seeds sired by each father was determined through SSRs and compared to the expected numbers based on the pollen mixture composition. All three mother genotypes of Abies nordmanniana had more progenies with the Abies alba as father (hybrids) than expected, based on proportions in the pollen mix. This indicates that no reproductive barriers between the two species exist, and that seed orchard managers should take precautions to avoid hybrids in seed crops. Furthermore, the experiments revealed quite different siring success of the three Abies nordmanniana genotypes, depending on which clone was the mother. Abies nordmanniana seed orchards should therefore not be established in the vicinity of Abies alba in the flowering age, and if a few-clone set up is chosen, the mating interaction should be investigated beforehand through pollen mix experiments.

Mots clés

  • Abies nordmanniana
  • Abies alba
  • hybridization
  • pollen mixture
  • seed orchard contamination
access type Accès libre

Spontaneous Hybridization between Pinus sylvestris L. and P. mugo Turra in Slovakia

Publié en ligne: 14 Oct 2017
Pages: 76 - 82

Résumé

Abstract

Molecular evidence for spontaneous hybridization between Pinus sylvestris L. and P. mugo Turra in the putative hybrid swarm populations of the species in Slovakia was provided based on PCR-RFLP analysis of the cpDNA trnV-trnH region. Species-specific restriction profiles generated by Hinf I digests of the cpDNA products reliably identified P. sylvestris and P. mugo haplotypes of the embryos from open pollination. Simultaneous analysis of the respective cpDNA region in megagametophytes and embryos of individual seeds along with needles of a given maternal tree has enabled to score either the P. sylvestris or P. mugo haplotypes in the embryos illustrating hybridization patterns between the two species. Data obtained in this way indicate a relatively extensive hybridization which takes place between P. sylvestris and P. mugo. The extent of hybridization varied among populations as evidenced by the 41.1-58.7% proportion of hybrid embryos registered on the locality Habovka, and by the 8.3% and 2.7% proportions of hybrid embryos on the localities Tisovnica and Sucha Hora, respectively. The approach itself is recommended as a convenient method for monitoring the hybridization patterns in sympatric zones of the studied pine species.

Mots clés

  • Pinus sylvestris L.
  • P. mugo Turra
  • hybridization
  • chloroplast DNA
  • restriction analysis
access type Accès libre

Primer Note: A New Set of Highly Polymorphic Nuclear Microsatellite Markers for Nothofagus nervosa and Related South American Species

Publié en ligne: 14 Oct 2017
Pages: 82 - 85

Résumé

Abstract

Nothofagus is the main component of southern South American temperate forests. Overexploitation in the past has led to the loss of 40% of the original distribution range. Genetic diversity as well as biological processes shaping the distribution of the genetic variation (e.g. gene flow) constitutes basic knowledge for the implementation of conservation measures and for the definition of Evolutionary Significant Units. Nuclear microsatellites are the marker of choice for gene flow and fine-scale genetic structure studies. We enlarged a previous set of microsatellites (SSRs) for South American Nothofagus species, with special concern to Nothofagus nervosa (Phil.) Dim. et Mil. Five new SSRs are presented with allele numbers up to 12 in a single population. The primers transferred well to five related species (N. obliqua (Mirb.) Oerst, N. glauca (Phil.) Krasser, N. dombeyi (Mirb.) Oerst , N. pumilio (Poepp et Endl.) Krasser and N. antarctica (G. Forster) Oerst, with allele numbers up to 11. The high level of polymorphism promises a sufficient power for gene flow and parentage analyses.

Mots clés

  • Nothofagus
  • microsatellites
  • South America
  • gene flow
  • fine-scale genetic structure
access type Accès libre

Genetic Variation in the Qinghai-Tibetan Plateau Endemic and Endangered Conifer Cupressus gigantea, Detected Using RAPD and ISSR Markers

Publié en ligne: 14 Oct 2017
Pages: 85 - 92

Résumé

Abstract

Assessing the level and distribution of genetic diversity of rare tree species is essential for their management and the development of effective conservation strategies. Cupressus gigantea is a long-lived endemic cypress of the west Qinghai-Tibetan Plateau and the tallest tree in its genus. The current populations of this species are fragmented and highly disturbed. We used RAPD (Random Amplified Polymorphic DNA) and ISSR (Inter-Simple Sequence Repeat amplification) markers to assess the genetic variation and population structure of this endangered cypress. The 15 RAPD primers used in this study amplified 108 reproducible bands, 49 (45.4%) of which were polymorphic, while the 12 ISSR primers amplified 94 bands, 65 (69.2%) of which were polymorphic. Analysis of Molecular Variance (AMOVA) indicated that 49.7% and 38.3% of the variation was attributable to differences between populations for the RAPD and ISSR markers, respectively; relatively high compared to values reported for other conifer species. These estimates were also similar to Gst values obtained from Nei’s gene diversity analyses (RAPD = 0.41 and ISSR = 0.36), and suggest that there is a high degree of population differentiation in this narrowly-distributed conifer. The genetic structure of this species has probably been shaped by its long life cycle and climatic changes during the Quaternary. The high degree of population differentiation in this species highlights the need for additional conservation measures, including measures to protect of all of the remaining populations. The substantial similarities between the results of the RAPD and ISSR analyses of samples from the same individuals indicate that they can be interpreted with high levels of confidence.

Mots clés

  • Cupressus gigantea
  • genetic diversity
  • ISSR
  • RAPD
  • Qinghai-Tibetan Plateau
access type Accès libre

Comparison of Genetic Structure Assessed by Amplified Fragment Length Polymorphism and Retrotransposon-based Sequence-specific Amplification Polymorphism for Portuguese Populations of Pinus pinea L.

Publié en ligne: 14 Oct 2017
Pages: 93 - 100

Résumé

Abstract

In order to assess genetic diversity within and among populations of Pinus pinea L. (stone pine), seven Portuguese populations originating from three Provenance Regions were selected and genotyped using two marker systems. We compared the genetic variation of these populations using retrotransposon-based sequence-specific amplification polymorphism (SSAP) and amplified fragment length polymorphism (AFLP). In total, 105 trees were screened with three primer enzyme combinations (PEC), producing 232 SSAP and 132 AFLP loci. Where SSAP yielded approximately twice-the number of polymorphic fragments compared to AFLP. Differentiation was slightly higher for SSAP, than for AFLP (FST = 0.105 for SSAP and 0.074 for AFLP), and both significantly different from zero, P < 0.01. The levels of average genetic diversity within-population found with the two types of marker were not significantly different between SSAPs and AFLPs (26.6% and 22.8%, respectively). The populations that displayed the highest and lowest genetic diversity scores were the same for both markers, and only two populations had significantly different He estimates. The neighbor-joining tree based on the Nei’s genetic distance displayed some geographic pattern. With the AFLP markers the populations grouped according to the provenance regions where they were sampled, resulting in one well supported cluster with the Southern populations, but with SSAP the pattern was not so coherent. In this study SSAP generated more polymorphic fragments and higher estimates of genetic diversity than AFPL did, due, probably, to the higher mutation rate of retrotransposition relative to base mutation. Nevertheless, congruence was found between estimates obtained with both markers, which is very interesting, for, in general, SSAP markers have lower costs compared to AFLPs, and they might be an interesting alternative marker system, when higher resolution is requested.

Mots clés

  • sequence-specific amplification polymorphism
  • amplified fragment length polymorphism
  • Pinus pinea
  • genetic structure.
access type Accès libre

Genetic Parameter Estimates for Growth Traits from Diallel Tests of Loblolly Pine Throughout the Southeastern United States

Publié en ligne: 14 Oct 2017
Pages: 101 - 110

Résumé

Abstract

Variation in heritability and in genetic correlation estimates were evaluated for juvenile tree height and volume for six testing areas of loblolly pine (Pinus taeda L.) in the southeastern United States. Variance components and their functions (heritability and type B genetic correlations) were estimated from 265 six-parent disconnected diallel series, tested in almost 1000 trials (4 tests per diallel series). Original data were collected at age 6 years from about one million trees (265 diallel series x 30 crosses x 36 trees per cross/site x 4 sites) planted in field tests. Genetic tests were from the second cycle of breeding in the North Carolina State University - Industry Cooperative Tree Improvement Program. The overall unbiased individual-tree narrow-sense heritability for height was 0.19 and for volume was 0.16. The broad-sense heritabilities for height (0.24) and for volume (0.22) were higher than narrow-sense heritabilities due to the presence of non-additive genetic variance. There were moderate regional differences in these estimates, with tests in the Lower Gulf Coastal Plain tending to have the highest heritabilities for growth traits. There was very little association between site index and heritability, but heritabilities were higher on sites with the highest survival and highest test precision. Genotype x environment interactions were generally low both for half-sib and full-sib families, indicating that families can be operationally deployed to different sites with little concern about unpredictable performance.

Mots clés

  • Genetic correlation
  • genetic gain
  • genotype x environment interaction
  • heritability
  • Pinus taeda L.
access type Accès libre

Genetic Variation in Reproductive Traits in a Clonal Seed Orchard of Prunus avium in Northern Spain

Publié en ligne: 14 Oct 2017
Pages: 110 - 118

Résumé

Abstract

In the present study we investigated the reproductive phenology of Prunus avium in a seed orchard located in northwestern Spain. The study was carried out with 103 clones from 7 provenance regions in northern Spain. The most advanced flowering stage on different dates and the number of flowers and cherries were monitored over two consecutive years. Significant differences among clones were found for all of the studied traits, with high broad-sense heritability estimates for all, except duration of flowering and synchronization index, both of which showed moderate heritability. In general, there was good overall reproductive synchronization in the seed orchard, although two groups of clones were differentiated. Clones from two out of the seven populations studied flowered later and were less well synchronized. The clonal differentiation was correlated with geoclimatic variables, suggesting that clones from lower altitudes and higher temperatures tend to an earlier flowering.

Mots clés

  • Wild cherry
  • genetic variation
  • flowering
  • genetic parameters
  • reproductive synchronization
  • geographic pattern
access type Accès libre

Strategies for Optimal Deployment of Related Clones into Seed Orchards

Publié en ligne: 14 Oct 2017
Pages: 119 - 127

Résumé

Abstract

This study deals with how the deployed proportion of each candidate clone can be decided at the establishment of a seed orchard when the breeding values are available for each candidate in a population of unrelated half-sib families. The following deployment strategies were compared: (a) truncation selection by selecting the clones with the breeding values exceeding certain threshold and deploying equal number of ramets (Truncation strategy); (b) truncation selection by selecting only one best individual within each family (Truncation unrelated); (c) maximizing gain at a given effective clone number (Linear deployment); (d) linear deployment by selecting one best individual within each family (Linear deployment unrelated) and (e) maximizing net gain at a given gene diversity (Optimal proportions). The study focused on the latest alternative and described its superiority and characteristics for a number of possible typical cases. The genetic gain adjusted for predicted inbreeding depression (Net gain), gene diversity and effective clone number were considered as the main ranking criteria. The strategies optimizing the number of related individuals and the linear deployment strategy with restriction on relatedness returned the highest Net gain. If there is a large diversity to select from (the status number of the candidates is more than 8 times greater than the status number desired in the seed orchard), a relatively simple advice is to select the best individual within the best families and deploy the clones linearly according to their breeding values (the number of families selected depends on the desired status number). If the diversity available to select from is small, it seems recommendable to allow half-sibs among the selections and use the Optimal proportions deployment strategy. As the breeding cycles proceed, the status number of the candidate population will decrease and the Optimal proportions strategy is likely to become more favorable.

Mots clés

  • co-ancestry
  • gene diversity
  • genetic gain
  • inbreeding
  • seed orchard
  • status number
access type Accès libre

Crossability Between Wild (Malus sylvestris) and Cultivated (M. x domestica) Apples

Publié en ligne: 14 Oct 2017
Pages: 127 - 130

Résumé

Abstract

Malus sylvestris, a native fruit tree of Europe, is believed to be threatened by hybridization with the omnipresent cultivated apple (Malus x domestica). In the present study a series of controlled crossings were carried out in order to establish whether M. sylvestris can hybridize with its near relative, M. x domestica. By looking at fruit set, seed production, germination percentages, and development of seedlings following inter- and intraspecific crossings, no indication of neither pre- nor postzygotic barriers to hybridization between the two species was found. This can have important implications for management of the genetic resources of M. sylvestris.

Mots clés

  • Malus sylvestris
  • Malus x domestica
  • crossability
  • hybridization
  • conservation
access type Accès libre

Provenance by Site Interaction of Pinus densiflora in Korea

Publié en ligne: 14 Oct 2017
Pages: 131 - 139

Résumé

Abstract

Thirty-six provenances of Pinus densiflora were evaluated for stability and adaptability for height growth at 11 test sites in Korea. The data were obtained from measurements at age 6 and analyzed using linear regression model and AMMI (additive main effect and multiplicative interaction) model. There was significant provenance by site interaction effect (p < 0.011). The interaction term explained 7.1% of total variation. While the regression model accounted for 15.8% of GxE interaction term, the AMMI model accounted for 74.9% with four PCA values. Most of the provenances were not significantly different from the unity (b =1.0), except for Inje (1), Jungsun (4), Bongwha (5), Koryung (26), Hamyang (30) and Seoguipo (36). Adaptability of provenances to the test sites was estimated with mean height growth and first AMMI component scores (IPCA 1). Inje (1), Bongwha (5), Taean (20) and Seoguipo (36) were specifically adapted to the high yielding environments. Considering the first and second AMMI components (IPCA 1 and IPCA 2, respectively) scores, Whachun (2), Samchuk (10), Joongwon (14) and Buan (29) provenances were more stable than others. The implication of GxE interaction was discussed in view of seed transfer and delineation of seed zones.

Mots clés

  • linear regression model
  • AMMI model
  • provenance test
access type Accès libre

Mixed Mating With Preferential Outcrossing in Acacia saligna (Labill.) H. Wendl. (Leguminosae: Mimosoideae)

Publié en ligne: 14 Oct 2017
Pages: 139 - 145

Résumé

Abstract

Acacia saligna is being developed as an agroforestry crop for the southern agricultural regions of Australia. This study investigated the breeding system of A. saligna to generate basic knowledge for breeding and utilization of the species. Allozyme markers were used to investigate the mating system of four populations of the species. All the populations had high outcrossing rates, with a mean multilocus outcrossing rate of 0.91. The implications of a highly outcrossed mating system to the utilization of A. saligna are discussed.

Mots clés

  • Acacia saligna
  • agroforestry
  • mating system
  • high outcrossing.
access type Accès libre

Genetics of Shrinkage in Juvenile Trees of Pinus radiata D. Don From Two Test Sites in Australia

Publié en ligne: 14 Oct 2017
Pages: 145 - 151

Résumé

Abstract

To examine the genetic control of wood shrinkage (radial, tangential and longitudinal) in juvenile wood of radiata pine (Pinus radiata D. Don), we assessed samples collected at breast height in two related progeny tests of age 8 and 9 years, established at two different sites in Australia. Green to oven-dry tangential and radial shrinkage for the outer-rings was similar at both sites. Similarly, mean longitudinal shrinkage for the outer-rings was similar at both sites (0.3%, ranging from 0.1 to 1.9 at Flynn and 0.4%, ranging from 0.02 to 1.6, at Kromelite). Mean longitudinal shrinkage for the inner-rings was 4 times greater than that of the outerrings at both sites. The magnitude of the gradient of longitudinal shrinkage from pith to bark (0.001 to 2.9%) is large enough to cause distortion problems including twist and warp, during drying of sawn boards. These values also suggest that shrinkage in the juvenile core of radiata pine is of major economic importance and therefore should be improved either through genetics or silviculture. Individual-tree narrow-sense individual heritability for tangential and radial shrinkage in the outer-rings (4-6) was moderate at Flynn (0.24 ± 0.09 and 0.26±0.07, respectively). There was a lack of significant genetic variation for longitudinal shrinkage in the outer-rings but significant genetic control for the inner-rings (1-2) (h2 = 0.26 ± 0.07). More samples per family are required to detect significant genetic variation for shrinkage traits than other traits due to higher background variation in sampling and measuring shrinkage traits relative to other wood quality traits such as density, microfibril angle (MfA), spiral grain and modulus of elasticity (MoE).

Mots clés

  • Pinus radiata
  • juvenile wood
  • distortion
  • shrinkage
  • genetic control
access type Accès libre

Molecular Cloning and Characterization of a cDNA Encoding Sedoheptulose-1,7-bisphosphatase from Mulberry (Morus alba var. multicaulis)

Publié en ligne: 14 Oct 2017
Pages: 152 - 157

Résumé

Abstract

A full-length cDNA encoding sedoheptulose-1,7-bisphosphatase (SBPase; EC 3.1.3.37) was cloned from mulberry (Morus alba var. multicaulis) by rapid amplification of cDNA ends (RACE). The cDNA consisted of 1,527 nucleotides with an open reading frame (ORF) of 1,179 nucleotides encoding a 393 amino acid protein of approximately 42.6 kDa. Sequence comparison analysis showed that mulberry SBPase (MSBPase) had high homology to other plant counterparts. Phylogenetic and molecular evolutionary analysis revealed that MSBPase fell into plant SBPase group. Moreover, SBPase and fructose-1,6-bisphosphatase (FBPase; EC 3.1.3.11) shared 28-32% identical residues, suggesting that the two enzymes originated from the same evolution branch. Molecular modeling indicated that each subunit of MSBPase was composed of α-helices and β-sheets joined by turns and loops, and folded into a structure of hexahedron shape which was very similar to FBPase.

Mots clés

  • sedoheptulose-1,7-bisphosphatase
  • fructose-1,6-bisphosphatase
  • cDNA cloning
  • mulberry
access type Accès libre

Genetic Diversity and Population Structure of Apricot (Prunus armeniaca L.) from Northern Pakistan using Simple Sequence Repeats

Publié en ligne: 14 Oct 2017
Pages: 157 - 164

Résumé

Abstract

A collection of 44 P. armeniaca accessions and three related species, from diverse geographic areas, covering the entire Northern hemisphere with emphasis on Pakistani apricots, was screened with 10 SSR primer pairs developed in apricot, to characterize the cultivars and establish their genetic relationship. Given the fact that the Central Asian region is considered a center of origin of apricot, particular attention was devoted to accessions from the Hunza region of Pakistan. The primers correctly amplified a repeatable polymorphic pattern, which unequivocally distinguished all genotypes under study. Altogether 123 alleles were identified with an average of 12.30 alleles per locus. The observed heterozygosity for individual loci ranged from 0.28 to 0.77 with an average of 0.64. A neighbour joining method identified four groups from: (A) Central Asia, (B) Irano-Caucasia, (C) Continental Europe and (D) North America. The dendrogram confirms the historic dissemination pathways of apricot from its centre of origin in Asia to the West. Apricot cultivars from the Hunza region (Northern Pakistan) revealed a high variability, as genetic diversity is still conserved due to the traditional practice of planting seeds from the best trees.

Mots clés

  • Genetic variation
  • microsatellites
  • eco-geographic groups
  • Hunza
  • center of origin
access type Accès libre

Genetic Variation in Frost Damage and Seed Zone Delineation within an Altitudinal Transect of Pinus devoniana (P. michoacana) in Mexico

Publié en ligne: 14 Oct 2017
Pages: 165 - 170

Résumé

Abstract

We explored the patterning of genetic variation among Pinus devoniana Lindl. (also known as P. michoacana Martínez) populations to develop guidelines for seed and seedling movements, intended for improving the matching between genotypes and environments regarding frost tolerance, in reforestation programs. Open-pollinated seed from 16 populations along an altitudinal transect (1600 to 2450 m) were collected near Morelia, State of Michoacán, México. A common-garden provenance test, established with 2.5-year-old seedlings, was assessed for frost resistance conducting a laboratory frost damage test (-9°C). Results indicate that there were significant differences among provenances (P = 0.0261) for frost damage. Variation among provenances was structured as an altitudinal cline, with populations from lower altitudes being the least tolerant to frost. Linear regression statistics suggest that for each increment of 100 m of provenance altitude, there will be a 5.2% decrease in frost damage. We suggest the use of two provisional altitudinal seed zones of 400 m breadth each (lower and upper limits for zone 1: 1600 m and 2000 m of altitude; for zone 2: 2000 and 2400 m, respectively), and for reforestation of a given site, the use of seedlings originated from seed of the same seed zone or within ±200 m of altitude from the elevation of the reforestation site.

Mots clés

  • Pinus devoniana
  • Pinus michoacana
  • altitudinal genetic variation
  • provenances
  • frost damage
  • frost hardiness
  • seed zoning
  • seed and seendling movement guidelines
access type Accès libre

Evaluation of Provenances of Eucalyptus camaldulensis and Clones of E. camaldulensis and E. tereticornis at Contrasting Sites in Southern India

Publié en ligne: 14 Oct 2017
Pages: 170 - 179

Résumé

Abstract

A total of 188 open-pollinated families of Eucalyptus camaldulensis Dehnh. from 18 Australian natural provenances and 15 selected Indian families of the “Mysore Gum” land race were evaluated in three provenance- family trials at contrasting sites in southern India. At two years of age, the fastest growth was recorded at the driest site in Tamil Nadu, where E. camaldulensis provenances from Queensland were superior to those from Northern Territory and Western Australia, and the Indian land race. Provenance differences were less pronounced at the two higher-rainfall sites in Andhra Pradesh and Kerala. Interaction of provenance performance with site was significant. Within- provenance individual-tree heritabilities for height and diameter at breast height (dbh) were low at the three individual sites, ranging from 0.08 ± 0.05 to 0.19 ± 0.05 for height and 0.10 ± 0.05 to 0.19 ± 0.04 for dbh. Across-site heritabilities, 0.07 ± 0.02 for both height and dbh, were lower than those at individual sites. Phenotypically superior trees were selected from these trials and seven other plantings of E. camaldulensis and Eucalyptus tereticornis Smith in southern India and cloned from basal coppice. A total of 78 E. camaldulensis and 27 E. tereticornis selections, together with thirteen commercially planted Eucalyptus clones and five superior natural provenance seedlots, were tested in clonal trials at three sites in southern India, the different individual treatments being tested at from one to three sites. Three years after planting, most clones selected from E. camaldulensis trials and the commercial Eucalyptus clones were superior in volume production to E. tereticornis clones and seedling controls at a dry site in Tamil Nadu. A smaller number of clones, particularly those of E. camaldulensis, were also superior to seedling controls at an intermediate-rainfall site in Andhra Pradesh. At a third high-rainfall site in Kerala, seedling controls were superior to all but four of 46 clones tested. Significant clone-by-site interaction was observed for growth traits. At the dry site in Tamil Nadu, clones varied widely in their wood basic density from 450 to 700 kg m-3, and there was no significant correlation of clonal values for growth and wood density. The results confirm that clones are best selected and tested in environments similar to those where they will be deployed.

Mots clés

  • Eucalyptus camaldulensis
  • E. tereticornis
  • clone
  • provenance trial
  • deployment
  • genotype-by-environment interaction
access type Accès libre

Short Note: Coefficients of Variation in Variables with Bounded Scales

Publié en ligne: 14 Oct 2017
Pages: 179 - 180

Résumé

Abstract

With a variable that is recorded on a scale with fixed bounds, it can be appropriate to use for the denominator of the coefficient of variation the square root of the (sign-independent) product of the differences between the mean and the two bounds of the scale. A simple illustrative example is given.

Mots clés

  • coefficient of variation
  • subjective rating
  • subjective score
  • binary variables
access type Accès libre

Genetic Variation in an International Provenance-Progeny Test of Pinus caribaea Mor. var. bahamensis Bar. et Gol., in São Paulo, Brazil

Publié en ligne: 14 Oct 2017
Pages: 181 - 187

Résumé

Abstract

A combined provenance-progeny test of Pinus caribaea var. bahamensis was established in Paraguaçu Paulista Experimental Station, São Paulo State, Brazil, in a “compact family” blocks design with 14 provenances, 2 to 10 families per provenance, 5 individuals per subplot, and 7 replications. Variation among and within island, provenances and families and genetic parameters for d.b.h., height, and real volume were investigated, about 15 years after planting. Analysis of variation for all studied traits revealed significant differences among islands, provenances within island and families within islands, suggesting the possibility of increasing the timber yield through selection of the more productive provenances and families within the best island. Genetic correlations on growth traits were high and statistically significant, indicating that substantial gains could be made through indirect selection for one trait based on direct selection for another. Norman Castle provenance from Abaco Island performed best for d.b.h. height and volume, while San Andros and Little Harbour Cay, both from Andros Island performed worst for d.b.h. and height, respectively, and South Riding from Grand Bahamas Island performed worst for volume. The best provenance growth compared to that P. elliottii var. elliottii species at the same experimental site suggests that P. caribaea var. bahamensis has high silvicultural potential for the Paraguaçu Paulista region.

Mots clés

  • Pinus caribaea
  • provenance-progeny test
  • genetic variation
  • genetic parameters
  • quantitative traits
access type Accès libre

Short Note: Root Restriction Hindered Early Allometric Differentiation Between Seedlings of Two Provenances of Canary Island Pine

Publié en ligne: 14 Oct 2017
Pages: 187 - 193

Résumé

Abstract

Based on the optimal partitioning theory, the comparative assessment of seedling allometry is a common task in retrospective genetic tests and early testing of forest reproductive material. Our hypothesis was that root restriction imposed by the container might hinder or rule out genetic differences in biomass allocation. We grew seedlings of two contrasted provenances of Canary Islands pine in mini-rhizotrons, 60 and 90 cm deep, and alternatively in standard bottom-open 200 cc forest containers. In the mini-rhizotrons, plants from the drier provenance allocated more biomass to roots, especially to the tap root and invested less in needles, both in a biomass and leaf area basis, and this morphological divergence increased between two harvests, undertaken at 57 and 115 days after planting. By contrast, confirming our hypothesis, at the 115 days harvest, the plants grown in standard containers did not exhibited significant differences between provenances for Leaf Mass Fraction, Root Mass Fraction and Leaf Area Ratio. We conclude that the physical constraint for root development imposed by small containers increases the probability of dismissing the genetic effect in biomass allocation when assessing forest reproductive materials at the short term, even when the whole plant growth (total dry weight) might be unaffected.

Mots clés

  • Mini-rhizotrons
  • root architecture
  • container
  • biomass allocation
  • ontogeny
access type Accès libre

Spatial Genetic Structure Within Two Contrasting Stands of Scots Pine (Pinus sylvestris L.)

Publié en ligne: 14 Oct 2017
Pages: 193 - 202

Résumé

Abstract

When considering neutral nuclear markers, genetic differentiation of Scots pine (Pinus sylvestris L.) populations is known to be low. The homogeneity arises particularly as an effect of common ancestry in a recent evolutionary history as well as an extensive gene flow, especially through pollen. However, within populations several other forces may shape the spatial distribution of genetic variation, including establishment history, environmental and silvicultural selection. These local forces are known to produce non-random spatial patterns of genetic variation, however little is known on fine-scale spatial genetic structure of Scots pine. In this study, two stands of this species with different establishment histories, selected within one larger population located in northern Poland were genotyped and analysed for genetic variation and within-stand spatial genetic structure. Results revealed no differences in genetic variation, although stands are separated about 60 km, suggesting that the two populations share a common genetic pool. The spatial genetic structure in both stands was found to be slightly different and was attributed to differences in the mode of populations’ establishments. Finally, results confirmed that gene flow in Scots pine is extensive, causing genetic homogeneity within a single population.

Mots clés

  • genetic structure
  • spatial autocorrelation
  • relatedness coefficient
  • forest management
  • colonization
  • Scots pine
access type Accès libre

Inbreeding Depression in the Full-sib Offspring of Populus nigra L.

Publié en ligne: 14 Oct 2017
Pages: 202 - 210

Résumé

Abstract

Controlled pollination was carried out in the species Populus nigra L. in a greenhouse on isolated branches between sisters and a brother - inbreeding (S x B). Female trees (sisters) were also exposed to open pollination (OP) in the neighbourhood of a male tree (brother) and other Populus nigra trees in the vicinity. The analysis of 11 microsatellites was done in the offspring from the inbreeding (S x B) and from the OP. In OP offspring was found 20-76% of viable individuals that were coming from pollination with brother’s pollen (spontaneous inbreeding). These individuals were separated from the offspring. In a randomised field trial the offspring were evaluated for two years. Fitness decreased in S x B offspring, traits of plant height, trunk diameter, height increment and resistance to Melampsora larici-populina Kleb. were lower in comparison with those of OP offspring. A coefficient of inbreeding depression (δ) ranged from 0.373 to 0.034. The significance of differences between the offspring from S x B and OP of the particular sisters was proved. About 30% of homozygous microsatellite loci were identified in inbred S x B offspring, which was more than in OP offspring. This difference was significant in the offspring of three sisters; it was not significant in the offspring of one sister. This trend corresponded to the results of growth traits.

Mots clés

  • inbreeding depression
  • open pollination
  • spontaneous inbreeding
  • microsatellites
  • Populus nigra L.
access type Accès libre

Short Note: The Genetic Correlation Between Air-dried Density and Basic Density in Eucalyptus Nitens Wood Cores

Publié en ligne: 14 Oct 2017
Pages: 210 - 212

Résumé

Abstract

Cores extracted from trees to assess wood chemistry are generally not used to assess basic density in eucalypt pulpwood breeding programmes, as the measurement of basic density requires high temperature drying. However, both wood chemistry and air-dried density can be assessed on the same core. This study found that the inter-trait genetic correlation between core air-dried and basic density to be effectively equal to one in two Tasmanian Eucalyptus nitens progeny trials. This implies that selection for basic density could be undertaken using air-dried density with little or no reduction in genetic gain, thus negating the need to extract a separate core to assess basic density and wood chemistry. The adoption of this practice could considerably reduce the cost of assessing these traits in eucalypt breeding programmes.

Mots clés

  • Eucalyptus nitens
  • selection trait
  • non-destructive assessment
  • air-dried density
  • basic density
  • wood chemistry
  • pulp yield
  • cellulose content
  • near infrared spectroscopy (NIR)
  • genetic correlation
access type Accès libre

Heterogeneity and Spatial Autocorrelation for Chloroplast Haplotypes in Three Old Growth Populations of Northern Red Oak

Publié en ligne: 14 Oct 2017
Pages: 212 - 220

Résumé

Abstract

In eastern North America, evidence for cryptic northern refugia could contribute to resolving Reid’s Paradox, the disparity between the rate of oak recolonization indicated by pollen deposition and the rate indicated by contemporary seed dispersal studies. Severe anthropogenic disturbance of oak-dominated forests throughout eastern North America followed by regeneration from isolated patches and deliberate planting in some regions could obscure the signal of discontinuity expected from small, cryptic refugia. In this study of northern red oak, Quercus rubra L., the dominant representative of Quercus section Lobatae in the eastern United States, we address the question of appropriate sample size for accurate detection of the biogeographical distribution of chloroplast haplotype diversity in Q. rubra. We examined chloroplast DNA (cpDNA) variation in all Q. rubra over 17 cm in diameter (310 trees) in three forest fragments with documented histories of minimal disturbance for the last 100-190 years. cpDNA polymorphisms in three intergenic regions revealed different haplotype frequencies between the two local fragments located within 1 km of each other and complete discontinuity for the predominant haplotype between these two sites and a site 207 km distant. Haplotypes displayed positive spatial autocorrelation over 10-40 meter distances. Sample sizes of 10 or fewer taken at 50 meter intervals along a linear transect yielded poor estimates of haplotype frequencies and did not accurately detect haplotype richness.

Mots clés

  • cpDNA
  • Quercus rubra
  • chloroplast
  • genetic diversity
  • patch size
  • postglacial migration
access type Accès libre

The Needle Volatile Composition of Pinus nigra J. F. Arnold, P. sylvestris L., P. densiflora Siebold et Zucc. and P. thunbergiana Franco Trispecies Hybrids

Publié en ligne: 14 Oct 2017
Pages: 221 - 226

Résumé

Abstract

The needle volatile composition of two trispecies hard pine hybrids produced by the controlled hybridization and their parents was researched with gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) in order to confirm their hybridity. The analysed trispecies hybrids were: (Pinus nigra x P. sylvestris) x P. densiflora (= nisyde) and (P. nigra x P. sylvestris) x P. thunbergiana (= nisyth). A total of 59 compounds was identified. All identified compounds were terpenes, except one. The trispecies hybrids showed the same qualitative pattern of the needle volatile composition as their parental species. However, there were quantitative differences in several major terpenes. According to the needle volatile composition the hybrids nisyde were more similar to the female parent, whereas the hybrids nisyth were more similar to the male parent. The hybrids nisyth had a considerably higher content of β-pinene (specific component of P. thunbergiana) than the other analyzed groups. The content of thunbergol (specific component of P. densiflora) in the hybrids nisyde was not considerably different in relation to the other groups. The intermediary quality of the hybrids nisyde and nisyth for most components in relation to their parents, as well as the previous morphometric analysis, confirms their hybrid character.

Mots clés

  • trispecies hybrids
  • (Pinus nigra x P. sylvestris) x P. densiflora
  • (Pinus nigra x P. sylvestris) x P. thunbergiana
  • needle volatiles
  • GC
  • GC/MS
access type Accès libre

The Chloroplast DNA Polymorphisms of White Oaks of Section Quercus in The Central Balkans

Publié en ligne: 14 Oct 2017
Pages: 227 - 234

Résumé

Abstract

A total of 444 oak trees from 110 populations from a previously under-sampled area in the central Balkans were analysed using four primer/enzyme combinations which amplified and restricted four, largely non-coding regions of the maternally inherited chloroplast DNA. Using the nomenclature of PETIT et al. (2002 a) to classify the haplotypes and lineages, the seven haplotypes that were found in Croatia, Bosnia and Herzegovina, Montenegro, Albania, Macedonia and southern Kosovo consisted of haplotypes 2, 4, 5, 6, 7, 17, 31, as well as the subtypes of haplotypes 4 (a), 5 (a, b, c), and 17 (a). Five of these haplotypes belong to lineage A. One of these, haplotype 5, is present throughout the sampled area. The distributions of the other haplotypes from this lineage are more geographically structured. The other two haplotypes, haplotype 2 and haplotype 17, belong to lineages C and E, respectively. The data are combined with previous data by PETIT et al. (2002 b) to provide more detailed information of the postglacial routes of colonisation taken by oaks in south-eastern Europe.

Mots clés

  • cpDNA polymorphism
  • Quercus
  • central Balkans
  • colonisation
  • glacial refugia
  • haplotypes
access type Accès libre

Paxillus involutus Forms an Ectomycorrhizal Symbiosis and Enhances Survival of PtCOMT-modified Betula pendula in vitro

Publié en ligne: 14 Oct 2017
Pages: 235 - 242

Résumé

Abstract

The ability of the PtCOMT (caffeate/5-hydroxyferulate O-methyltransferase from Populus tremuloides L.) - modified Betula pendula Roth. lines to form symbiosis with an ectomycorrhizal (ECM) fungus Paxillus involutus Batsch Fr. was studied in vitro. Lignin precursor gene PtCOMT was introduced into two B. pendula clones under the control of the cauliflower mosaic virus 35S promoter or the promoter of the sunflower polyubiquitin gene UbB1. Of the four transgenic lines, one 35SPtCOMT line (23) had a decreased syringyl/guaiacyl (S/G) ratio of root lignin, and two UbB1-PtCOMT lines (110 and 130) retarded root growth compared to the control clone. Both control clones and all transgenic lines were able to form ECMs with P. involutus, but the transgenic lines differed from the controls in the characteristics of the ECMs. The number of lateral roots covered with fungal hyphae and/or development of a Hartig net (HN) were reduced in line 23 with a decreased S/G ratio, and in lines 110 and 130 with slower root formation and changed root morphology, respectively. However, line 23 benefited more from the inoculation in lateral root formation than the control, and in lines 110 and 130 the percentage of viable plants increased most due to inoculation. The results show that B. pendula plants genetically transformed with the lignin gene PtCOMT could form mycorrhizal symbiosis regardless of changes in either the root S/G ratio or development. The benefits of the symbiosis were variable even in the closed in vitro system, and dependent on the clone or transgenic line and the ECM fungal symbiont.

Mots clés

  • Betula pendula
  • COMT
  • ecological impacts of gmtrees
  • ectomycorrhiza
  • lignin modification
  • Paxillus involutus
access type Accès libre

Genetic Diversity of the Relict Plant Taiwania cryptomerioides Hayata (Cupressaceae) in Mainland China

Publié en ligne: 14 Oct 2017
Pages: 242 - 249

Résumé

Abstract

The genetic diversity and differentiation of five populations of Taiwania cryptomerioides Hayata in mainland China were investigated using inter-simple sequence repeats (ISSR). In comparison with other coniferous species, T. cryptomerioides from mainland China possesses little genetic variation, particularly at the level of individual populations (the percentage of polymorphic loci, Nei’s gene diversity and Shannon’s indices of diversity at the species and population levels are 38.02%, 0.1326, 0.1986 and 9.27%, 0.035, 0.0518 respectively). In contrast, the level of population differentiation is much higher (GST: 0.7269; Shannon’s genetic differentiation: 0.7392; Hickory è B: 0.668; AMOVA genetic differentiation: 72.37%). The genetic divergence of pairs of populations was not significantly correlated with the geographical distance separating them. Current patterns of genetic variation were related to biogeographic history and the small population size. On the basis of these findings, we discuss the development of conservation strategies for this endangered species.

Mots clés

  • Taiwania cryptomerioides
  • genetic diversity
  • ISSR
  • China
  • relict species
  • conservation
access type Accès libre

Genetic Variation Within Two Sympatric Spotted Gum Eucalypts Exceeds Between Taxa Variation

Publié en ligne: 14 Oct 2017
Pages: 249 - 256

Résumé

Abstract

Population substructure and hybridization, among other factors, have the potential to cause erroneous associations in linkage disequilibrium (LD) mapping. Two closely related spotted gum eucalypts, Corymbia variegata and C. henryi (Myrtaceae) occur in sympatry in the east coast of Australia and potentially interbreed. They are morphologically similar but are distinguished as separate species based on capsule and foliage size. To determine whether they hybridize in nature and its implications for LD mapping, we investigated the level of molecular divergence between the two species at two sympatric locations separated by 300 kilometres. Very few individuals of intermediate morphology were identified, despite the two species occurring only metres apart. Analysis of genetic structure using 12 microsatellite loci showed that genetic differentiation between populations of the same species at different locations (FST = 0.07 for both species; p = 0.0001) was significantly higher than that observed between species at each location (mean FST = 0.02 and 0.04 for Cherry tree and Bunyaville respectively; p = 0.0001; all Mann-Whitney U-test p ≤ 0.01). No species-specific alleles or significant allele frequency differences were detected within a site, suggesting recurr#ent local gene flow between the two species. The lack of significant allele frequency differences implies no population stratification along taxonomic lines. This suggested that there is little concern for cryptic hybridization when sampling from sites of sympatry for LD mapping.

Mots clés

  • panmixia
  • hybridization
  • gene flow
  • association mapping
  • population structure
  • admixture
  • reproductive isolation
  • linkage disequilibrium
access type Accès libre

Pollen Dispersal and Its Spatial Distribution in a Seed Orchard of Larix kaempferi (Lamb.) Carr.

Publié en ligne: 14 Oct 2017
Pages: 256 - 261

Résumé

Abstract

Pollen dispersal and its spatial distribution in a seed orchard of Larix kaempferi in Changlinggang, Jianshi, Hubei Province has been studied for 3 years. The results show that pollen dispersal is directly affected by weather conditions, with wind speed being the main factor controlling pollen dispersal. Pollen dispersal follows a date rhythm of low-high-low during the whole pollen dispersal season with a peak date for 3-5 days, and a time rhythm of low-high-low with the peak time at 10:00-16:00 during the day. For pollen density in the air there are significant differences among dates, and among different day times during dispersing. There are no significant differences between pollen densities in space with regard to horizontal directions, 8 orientations, and different positions in the tree crown in this seed orchard, in all of these cases pollens are evenly distributed. There are significant differences for pollen densities among different vertical heights, showing a cluster distribution type. The pollination level in this seed orchard is very low and needs a supplement mass pollination (SMP).

Mots clés

  • Larix kaempferi (Lamb.) Carr
  • seed orchard
  • pollen dispersal
  • spatial distribution
  • pollination level.
access type Accès libre

Discrimination between seedlings of Eucalyptus globulus, E. nitens and their F1 hybrid using near-infrared reflectance spectroscopy and foliar oil content

Publié en ligne: 14 Oct 2017
Pages: 262 - 269

Résumé

Mots clés

  • eucalypt
  • spectra
  • 1,8-cineole
  • NIRS
  • fresh leaves
  • discriminant analysis
  • partial least-squares regression
access type Accès libre

Genetic Parameters of Somatic Clones of Coastal Douglas-fir at 5½-Years across Washington and Oregon, USA

Publié en ligne: 14 Oct 2017
Pages: 269 - 275

Résumé

Abstract

Five genetic tests involving 70 somatic clones of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were planted March-April 1999 in Weyerhaeuser plantations across western Washington and Oregon states, USA. Four of the tests are in Longview and Twin Harbors regions of Washington, and one test is in Springfield, Oregon. Each test is based on single-tree plots with 12 randomized complete-blocks. The 70 coastal Douglas-fir clones were propagated by somatic embryogenesis from two full-sib families that had the same female parent. Results are reported for survival, height, diameter at breast-height (DBH) and volume growth at 5½-years. These tests provide evidence of acceptable growth and survival of somatic trees of coastal Douglas-fir across a range of site conditions. Height had a clonal heritability of 0.25 ± 0.01, DBH 0.21 ± 0.01 and volume 0.20 ± 0.01. The growth traits were all strongly genetically associated with clonal correlations of 0.92 to 0.99. Clonal performance for growth proved quite stable across tests with an overall between-test correlation of 0.84 ± 0.04. There was little variance due to clone x test interactions.

Mots clés

  • Coastal Douglas-fir
  • somatic embryogenesis
  • adaptability
  • clonal heritabilities
  • clonal stability
access type Accès libre

Height–Diameter Relationships for Jack Pine Seedlots of Different Genetic Improvement Levels

Publié en ligne: 14 Oct 2017
Pages: 276 - 282

Résumé

Abstract

Differences in height-diameter (H-DBH) relationship were investigated using the Chapman-Richards function among jack pine seedlots planted in a realized genetic gain test in New Brunswick. Three seedlots representing the bulk mixed cone collection from the 1979 J.D. Irving’s first-generation seedling seed orchard (JDISSO) before rogueing (UNR), after the first time genetic rogueing (1STR) and after the second time genetic rogueing (2NDR), respectively, were planted in the test. Unimproved commercial seedlots (UC) were also included for comparison. Results indicate that an overall H-DBH relationship for all the seedlots was not appropriate. Seedlot pairwise comparisons in H-DBH relationships showed that, whereas most seedlot pairs were significantly different from each other, there was no significant difference between the UNR and UC and between the 1STR and 2NDR. Two models were developed with one targeting the UNR and UC (UNIMPROVED) and the other targeting the 1STR and 2NDR (IMPROVED). The difference between the UNIMPROVED and IMPROVED models was caused only by asymptote of the Chapman-Richards function. Applying the UNIMPROVED or IMPROVED model to predict height of the 1STR and 2NDR or the UNR and UC would result in an under-estimated or an over-estimated bias by 2 to 3% in height. In light of this study, seedlot differences in H-DBH relationships should be integrated into growth and yield models by a multiplier for height depending on genetic improvement levels.

Mots clés

  • Pinus banksiana
  • tree improvement
  • realized gain test
  • Chapman-Richards function
  • extra sum of squares method
  • growth and yield.
access type Accès libre

A Strategy for the Second Breeding Cycle of Larix x marschlinsii in Québec, Canada Including Experiments to Guide Interspecific Tree Breeding Programme

Publié en ligne: 14 Oct 2017
Pages: 282 - 291

Résumé

Abstract

A strategy for the genetic improvement of Larix decidua P. Mill., L. kaempferi (Lamb.) Carrière and their hybrid (L. x marschlinsii Coaz) in Québec, Canada, was set up to provide short and long-term genetic gains, as well as basic populations for some fundamental experiments. A reciprocal recurrent selection with forward selection strategy (RRS-FS) will be applied by using a pollen mix breeding with a partial population paternity analysis (PMX/WPPA). The genetic mechanisms responsible for heterosis among trees remain poorly understood. This complicates the implementation of multi-species genetic improvement programmes seeking to achieve the full benefits of interspecific hybridization. Various strategies to exploit heterosis are outlined. To expand our knowledge and guide our future choices, basic research has been integrated directly into breeding and testing activities, as well as through experiments integrated within activities leading to recommendations about the top-ranked families to be used in reforestation (cuttings). These experiments can also serve as the basis for future studies seeking a better understanding of heterosis through molecular genetics.

Mots clés

  • paternity analysis
  • heterosis
  • interspecies hybrid
  • interspecific breeding strategy
  • polymix crossing
  • Larix x eurolepis
access type Accès libre

Low Chloroplast DNA Diversity in Red Dogwood (Cornus sanguinea L.)

Publié en ligne: 14 Oct 2017
Pages: 291 - 300

Résumé

Abstract

The red dogwood Cornus sanguinea L. is a deciduous shrub of the temperate and Mediterranean zones. It is often used in landscape gardening for miscellaneous purposes. Chloroplast DNA markers, the so-called cpDNA haplotypes, are a very potential marker type to characterise the large scale variation pattern within the natural range of a species. In this study, a total of 86 populations and 673 individuals were sampled all over Europe. Eight different haplotypes were recognised by combinations of several PCR-RFLP patterns. They are divided into 3 groups of related types. There is no association between these 3 groups and their geographic occurrence within the tested material. One haplotype strongly dominates in the whole distribution area. It takes nearly 90 percent whereas the remaining seven haplotypes together reach to approximately 10 percent. Besides the low number of haplotypes, the total genetic variation HT = 0.15 is much lower in Cornus sanguinea compared to other European tree and shrub species. Despite the low level of variation, several cases of introduced populations could be detected. Other haplotypes than the common type are found only in narrow areas. This result indicates that after the colonisation of the European continent only a very restricted gene flow could have taken place.

Mots clés

  • Cornus sanguinea L.
  • red dogwood
  • genetic variation
  • chloroplast DNA
  • PCR-RFLP
  • haplotypes
  • gene flow
  • distribution area
  • introduced populations.
access type Accès libre

Comparative Meiotic Chromosome Studies in Nine Accessions of Tecomella undulata (Sm.) Seem., Threatened Tree of Indian Desert

Publié en ligne: 14 Oct 2017
Pages: 301 - 306

Résumé

Abstract

Meiotic studies were carried out in nine different accessions of T. undulata collected from three districts of Rajasthan, India. Data collected on chromosome associations, chiasma frequency and their distribution pattern concluded that the somatic chromosome number of T. undulata is 2n = 2x = 36 which is at variance with published literature. The high frequency of 18:18 chromosome distribution at anaphase I and an overwhelming percentage of stainable pollens observed are indicative of overall genomic stability as supported by complete absence of accessory chromosomes (B) and supernumerary nucleoli. Numerical alteration of chromosomes might have played an important role in origin and adaptation of T. undulata to the adverse climate conditions of Indian desert.

Mots clés

  • genetic variation
  • meiotic studies
  • threatened tree
  • Tecomella undulata
  • Bignoniaceae
access type Accès libre

Genotype by Environment Interaction in Pinus sylvestris L. in Southern Sweden

Publié en ligne: 14 Oct 2017
Pages: 306 - 311

Résumé

Abstract

To estimate the amount of genotype by environment interaction (G x E) data was obtained within the Swedish breeding program of Pinus sylvestris L. The calculations were based on estimates of G x E expressed by the genetic correlations across trials. In total, 66 progeny trials were included coming from 17 different test series. The number of parents tested per progeny trial was in average 52. Some parents were tested in several series and in total 812 parents were represented in the study. The results of our study showed that the amount of G x E for growth traits in Pinus sylvestris in southern Sweden was low. The median genetic correlation across trials for height, height increment and diameter were in the range 0.75-0.80 and the pattern of interaction was largely unpredictable from site differences in site index, latitude, longitude and altitude.

Mots clés

  • Scots pine
  • genetic correlation
  • stability
  • progeny testing
access type Accès libre

Genetic Variation in Resistance Against Heterobasidion annosum (Fr.) Bref. in Picea abies (L.) Karst. Expressed After Inoculation of Neighboring Stumps

Publié en ligne: 14 Oct 2017
Pages: 312 - 324

Résumé

Abstract

Based on the well-established knowledge that important spread of H. annosum is performed through spore infection of stumps and subsequent spread of mycelium to neighboring trees at points of root contact, an inoculation experiment was established in three adjacent fully pedigreed 17-year old Norway spruce field trials. In June 1995, every third row was cut and stump-inoculated with conidia belonging to the two contrasting types, P and S. 5 years later the remaining trees were evaluated by clear-cutting and mapping of rot occurrence. 34% of the trees were attacked. For each host-tree, the most likely source of infestation (i.e. possible inoculated donor-stump 5 years earlier) was evaluated based on orientation of the rot on the stump surface supplemented with samples of re-isolation of H. annosum of the two types. According to these estimates, the tested S-type turned out to be more aggressive towards Norway spruce than the tested P-type. Genetic variation in resistance was most convincingly detected in the most informative trial F175B. The pattern of genetic variation in the two roles as donor and host seems to differ. However, genetic variation was also expressed as general resistance, which is defined as the combined effect of donor stump, living host and across the two tested types of H. annosum. No indication of host x pathogen interaction was detected. This evidence combined with the general experience that resistance against root rot pathogens usually is partial and based on the cumulative effects of several genes, suggests that sustainable genetic gains in relative resistance may be obtainable in breeding programs of Norway spruce. The developed experimental set-up represents a useful concept for screening existing genetic trials for field resistance within a time scale of 5-6 years.

Mots clés

  • Heterobasidion annosum
  • Picea abies
  • genetic variation
  • resistance
  • stump inoculation
access type Accès libre

Microsatellites Reveal Clonal Growth and Genetically Distinct Groups in Cryptocarya chinensis in Fragmented Lower Subtropical Forest, China

Publié en ligne: 14 Oct 2017
Pages: 324 - 332

Résumé

Abstract

The lower subtropical monsoon evergreen broadleaved forest in South China (about 22° ~ 24° N) has a high conservation status, because of its uniqueness and high biodiversity. During the last few decades, most of these forests have been destroyed, and the remaining are being degraded by fragmentation. However, genetic information concerning the effects of fragmentation is currently lacking for plant species in these forests. In this study, therefore, eight microsatellites were used to study six Cryptocaya chinensis fragmented populations in Guangdong Province South China, and the results revealed a complex pattern of genetic variation within and among C. chinensis populations. Firstly, genetic variations demonstrate hitherto undetected clonal growth in C. chinensis. Secondly, current population structure of C. chinensis reflects an interaction between ancient homogeneous level of genetic variation and contemporary bottleneck via fragmentation. Small populations maintain substantial genetic variation of the initial populations through clonal growth, and do not show genetic depauperation compared to larger populations. Finally, two genetically distinct groups (West and Middle- East groups) are found in this area, connected by highly mixed contact zone.

Mots clés

  • clonal growth
  • Cryptocarya chinensis
  • habitat fragmentation
  • microsatellite
  • genetically distinct groups
  • contact zone
  • genetic diversity
access type Accès libre

Genetic Differentiation of Jack Pine (Pinus banksiana) and Red Pine (P. resinosa) Populations From Metal Contaminated Areas in Northern Ontario (Canada) Using ISSR Markers

Publié en ligne: 14 Oct 2017
Pages: 333 - 340

Résumé

Abstract

Metal accumulation in soil and plant tissues has caused severe ecological damage in forest ecosystems in the Sudbury region. The main objective of the present study was to determine the levels of genetic diversity in jack and red pine populations growing in metal contaminated and uncontaminated areas. Newly introduced populations were compared to 40 to 60 old populations. For jack pine, the percentage of polymorphic loci (P %) ranged from 14.6% to 45.8% with a mean of 31.6%. Nei’s gene diversity (h) varied from 0.046 to 0.169 with an average of 0.100, and Shannon’s index (I) ranged from 0.070 to 0.250 with an average of 0.153. The level of genetic variation was much lower in the red pine populations. For this species, the level of polymorphic loci varied from 4.55% to 27.27%. The mean for Nei’s gene diversity and Shannon’s information index, were 0.034 and 0.053, respectively. The highest genetic diversity values were observed in new plantations being developed by the Sudbury reforestation program. Overall, the genetic distance among the Pinus banksiana populations revealed that all the populations analyzed were genetically close to each other. There was no association between metal accumulation and genetic diversity for both species.

Mots clés

  • Jack pine
  • red pine
  • ISSR
  • genetic diversity
  • metal contamination
  • Sudbury
access type Accès libre

Genetic Variation in Early Growth Characteristics of Two Populations of Wild Service Tree (Sorbus torminalis (L.) Crantz) and Their Interrelationship

Publié en ligne: 14 Oct 2017
Pages: 340 - 348

Résumé

Abstract

This study was performed in order to compare two wild service tree populations (Sorbus torminalis (L.) Crantz) for their early growth and to find useful vegetative characteristics to be used in indirect selection of fast and tall growing trees of the species in the field. We used phenotypic and genotypic correlation coefficients estimated on data from 30 three-year old seedlings of each 40 randomly selected adult trees. Assuming genetic differences between the trees sampled, path analysis was performed on genotypic and phenotypic levels. Results showed that plus trees of one of the sites may be used for clonal seed orchard establishment. But the other site is suggested as a better site for breeding purposes with more effective Sorbus population. Collar diameter had the strongest positive direct effect and strongest correlation with plant height at the phenotypic level. In contrast, lateral branches showed very weak direct effect but relatively strong total indirect effect on plant height. Path analysis on the genotypic correlation coefficients detected negative indirect effect between the characters. Collar diameter could be regarded as a good predictor of plant height because of its strong direct and indirect phenotypic and genotypic correlations. The use of recommended selection criteria is discussed.

Mots clés

  • Genotypic correlation
  • Half-Sib progenies
  • Path analysis
  • Vegetative characteristics
access type Accès libre

Genetic Variation in Two Rare Endemic Mexican Trees, Magnolia sharpii and Magnolia schiedeana

Publié en ligne: 14 Oct 2017
Pages: 348 - 356

Résumé

Abstract

Patterns of genetic variation were examined within two endemic tree species restricted to Mexican cloud forest, Magnolia sharpii and Magnolia schiedeana. Leaf samples collected from natural populations were analysed using PCR RFLP of cpDNA, Inter-SSR and isozyme genetic markers, which were used to test a series of hypotheses regarding patterns of intraspecific variation within the two species. Genetic diversity estimates derived from Inter-SSR markers (mean Spop of 0.56 and 0.50 for M. sharpii and M. schiedeana respectively) are comparable to values obtained for other tree species. As predicted on the basis of its larger geographic range, the degree of population differentiation was found to be higher within M. schiedeana than M. sharpii, with 12.9% and 3.4% of total variation recorded between populations for the two species respectively using isozymes, and 26% and 11% using Inter- SSR markers. Isozyme analyses indicated negative Fis values, which may be suggestive of inbreeding in populations of M. sharpii, but provided less evidence of inbreeding in M. schiedeana. On the basis of PCR RFLP analysis of cpDNA, two chloroplast types were differentiated, type A being recorded for all of the individuals of both species, with the exception of one population of M. schiedeana that was fixed for type B. These results are consistent with recent evidence suggesting that some endemic plant taxa are able to maintain relatively high diversity within populations despite the occurrence of inbreeding and genetic drift, and that species with wider geographic ranges tend to exhibit relatively high genetic differentiation among populations. Conservation strategies for these species need to take into account the significant genetic differences recorded among the populations studied.

Mots clés

  • cloud forest
  • conservation biology
  • genetic variation
  • isozyme
  • cpDNA
  • PCR-RFLP
  • Magnolia sharpii
  • Magnolia schiedeana
access type Accès libre

The Effect of Altitude on the Pattern of Gene Flow in the Endemic Canary Island Pine, Pinus canariensis

Publié en ligne: 14 Oct 2017
Pages: 357 - 363

Résumé

Abstract

Pinus canariensis is endemic to the western Canary Islands (NW coast of Africa), where it forms forest spanning an altitude from 500 to 2500 m. There are dramatic changes in environmental conditions (temperature, moisture and solar radiation) over short distances due to this elevation gradient in the Canary Island pine forest. Those differences in environmental conditions may lead to asynchronous flowering times among elevations. In this study we used nuclear and chloroplast microsatellites to characterize the genetic structure of two altitudinal transects on the southern slopes of Tenerife Island to test for genetic isolation among altitudes. Although significant differentiation among sites was detected, this differentiation was very low (FST = 0.013 with chloroplast markers, FST= 0.019 with nuclear markers) and appeared to be unrelated to altitude. The contrasting results between nuclear and chloroplast markers are also discussed in terms of statistical accuracy of markers and genome inheritance.

Mots clés

  • chloroplast microsatellites
  • nuclear microsatellites
  • population differentiation
  • isolation by altitude

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