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

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

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

Chercher

38 Articles
Accès libre

Genetic Variation in Growth Curve Parameters of Konishii fir (Cunninghamia lanceolata (LAMB.) HOOK. var. konishii)

Publié en ligne: 19 Oct 2017
Pages: 1 - 10

Résumé

Abstract

Cunninghamia konishii is the island race of the species complex C. lanceolata, and is native to Taiwan. It is a valuable timber species. A comprehensive provenance- family test was established in 1973. Height and diameter were measured periodically until age 26, which was close to the species’ harvest age of about 30. These data offered an opportunity to examine the species’ growth characteristics by fitting asymptotic growth functions. We adopted the concept of repeated measures data analyses, i.e., a combination of variance component analysis and growth curve fitting, the latter involved fitting the individual tree height and diameter data to a Weibull-based function. A severe typhoon in 1996 caused serious damage to the plantation, mostly to tree heights. To prevent this damage from influencing our results, we limited the analyses to those trees judged relatively free of typhoon damage, and focused on the diameter growth data. Fitting a Weibull function with parameters a, b, and c was statistically successful (e.g. the mean R2 for diameter was 0.98). Both analyses indicate substantial variation among provenances and families, and thus opportunities for genetic selection and breeding. We particularly expound on the practical applications of growth curve fitting as an analytical tool for elucidating the mechanistic process of tree growth to assist decisions on the age for selection, even retrospectively, and modeling the response of tree growth to future climate.

Mots clés

  • Cunningham lanceolata var. konishii
  • provenance
  • repeated measures
  • growth curve fitting
  • Weibull function.
Accès libre

Genetic Parameters of Growth Traits and Wood Density in Eucalyptus grandis Progenies Planted in Argentina

Publié en ligne: 19 Oct 2017
Pages: 11 - 19

Résumé

Abstract

To determine the genetic parameters of growth traits and wood density (estimated by Pilodyn penetration) in a population of Eucalyptus grandis formed by families from 11 seed origins in NE Queensland, Australia and a local land race, 8.5-year-old progenies established in three sites in NE Argentina were evaluated. Local trees exhibited higher growth rate at two sites and better stem form, but also deeper Pilodyn penetration, at all sites; thus, there is potential to infuse new genetic variation into the current breeding population in the region. A significant amount of genetic variation was found for all traits assessed, with growth traits [diameter (DBH), height (HT) and volume (VOL)] showing different genetic structure and degree of genetic control as compared to stem straightness (FORM), bark thickness (BARK) and Pilodyn penetration (PILO). The effect of origin was negligible for growth traits while it was important for the other traits, so it should be considered in the selection strategy; in addition, individual heritability for growth traits (0.11-0.16 in the combined analyses) was generally lower than for the other traits (0.20-0.35). Genetic correlations between sites for all traits were high enough to indicate that genotype-environment interaction would not affect the selection program by using a single breeding population for this region. Genetic correlations between growth traits were high (rg > 0.80), and negligible between these and FORM; the only unfavorable genetic correlation was between PILO and BARK (rg = -0.44). Age-age correlations for growth traits and FORM were very high (rg > 0.90). Results suggest that all traits evaluated could be handled in a breeding program, either independently or combined, without negative correlated effects. Early selection for growth traits and stem form is also possible, with major savings in time.

Mots clés

  • Heritability
  • genetic correlation
  • age-age correlation
  • genetic stability
  • variance components
  • Pilodyn.
Accès libre

Genetic Diversity in Kenyan Populations of Acacia senegal (L.) Willd. Based on ISSR Markers

Publié en ligne: 19 Oct 2017
Pages: 20 - 28

Résumé

Abstract

Acacia senegal (L.) Willd is an African arid and semi arid zones, leguminous multipurpose tree species belonging to the subfamily Mimosoideae, family Fabaceae and subgenus Aculeiferum, highly valued for gum arabic production. Patterns of genetic diversity of this important species in Kenya have not been studied for efficiency of germplasm utilization, conservation and improvement. Four natural populations of A. senegal in Kenya (Bulla Sambul, Kutulo, Wamba and Meisori) were analyzed to estimate genetic variation among and within populations, by use of ISSR (Inter-simple sequence repeat) markers. Using five primers, 17 polymorphic loci were observed, ranging in size from 564bp to 983bp. A high mean total genetic diversity index for the species was observed (H= 0.27). The principal coordinates analysis (PCoA) of the 95 samples from the four populations showed that about 40.75% of the total variation was described by the first two axes with much overlap among populations; hence populations were not defined on the basis of geographic distance. Much of the genetic variation resided within the populations based on the coefficient of gene differentiation (Gst = 0.0573) and Analysis of Molecular Variance (AMOVA) (95%). It was therefore recommended that selection for the desired important economic traits for improvement and conservation should emphasize on individual trees within populations rather than among populations, and also ensure a comprehensive coverage of the entire ecological amplitude of the populations.

Mots clés

  • Acacia senegal
  • genetic diversity
  • ISSR
  • multipurpose
  • Kenya
  • differentiation
  • population
  • geographical structuring
  • selection
  • conservation.
Accès libre

A New Breeding Strategy for Pinus radiata in New Zealand and New South Wales

Publié en ligne: 19 Oct 2017
Pages: 28 - 38

Résumé

Abstract

A new breeding strategy is presented for the Radiata Pine Breeding Company, a New Zealand based research consortium, that drives the breeding program for Pinus radiata for both the New Zealand and New South Wales based Australian forest plantation industry. The new strategy builds on the existing base for P. radiata, and on the last strategy review in 2000. The new strategy comprises a large open-pollinated (OP) Main Population (MP) with 500 female parents and two sublines (250 female parents per subline). The MP will be tested using alpha designs, single-tree plots and incomplete blocks to maximise efficiency. Each subline will be tested on four sites, geographically distant from the other subline. The MP will be managed in discrete generations. Selection of the next generation will be using a combination of backward and forward selection, but the strict control of inbreeding with identified lineage will rely on the development of parental reconstruction for OP progeny. There are alternatives to this, however, such as estimating the group coancestry and accepting some additional increase in inbreeding. This is a new and significant departure from previous breeding strategies for P. radiata in New Zealand. There will also be a single, small Elite Population (EP), tested 50% as progeny and 50% as clones. Twenty four parents will be tested each year as clones and 24 as seedling progeny with some overlap between the two. It is expected that the clonal population will capture the greatest gains in traits with low heritabilities, and the half-sib progeny will capture the greatest gains in traits with high heritabilities. The two sublines will be maintained in the EP, and breeding will be managed as a rolling front with trials established every year, while trials of the MP will be established every 10 years.

Mots clés

  • Australia
  • clones
  • genetic gain
  • sublining
  • mating system.
Accès libre

Short Note: Genotype-Environment Interactions for Coastal Douglas-fir Grown to 21 Years Across Western Washington State, USA

Publié en ligne: 19 Oct 2017
Pages: 39 - 42

Résumé

Abstract

This study involves polymix families of coastal Douglas- fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) that were created by crossing parents selected from the Cascade, Longview, Twin Harbors and Vail wild populations of western Washington State. Eight to 10 female parents from each population were crossed using pollen-mixes of males from either the same or different populations. In 1985 these polymix families were planted across six genetic tests located in Cascade, Longview and Twin Harbors (two tests per region). Variance components are reported for over-bark breastheight diameter measured at 21 years (DBH21). Genotype x environment (GE) interactions involving different wild populations of Douglas-fir accounted for little variation in DBH21 across the western Washington regions studied. Interaction involving female parents nested within populations was the most important GE effect; explaining 2% of total variation in DBH21. However, this interaction was of limited practical importance since the superior female parents for DBH21 generally showed good stability across tests. Results from this study support selection of superior coastal Douglasfir genotypes that can produce strong, stable growth across a range of site environments encountered in western Washington.

Mots clés

  • Coastal Douglas-fir
  • genotype x environment
  • genetic stability
  • breast-height diameter.
Accès libre

Growth Rhythm Parameters as Components of Hybrid Vigour in Young Seedlings of Hybrid Larch (Larix decidua x L. kaempferi)

Publié en ligne: 19 Oct 2017
Pages: 42 - 53

Résumé

Abstract

Heterosis for growth traits was investigated on 2-yrold seedlings from related intra- and inter-specific progenies collected in hybridisation seed orchards combining Larix decidua (EL) and L. kaempferi (JL). Following taxa identification, seedlings phenology and growth were observed over a complete growing season in two experiments. Start, cessation, duration and rates of growth for the different taxa were explored in relation to hybrid vigour. Variable levels of heterosis were observed, depending on the genetic background of the parental species, the species over which superiority was evaluated, environmental conditions and the traits considered. While significant and consistent differences have been observed between hybrids and their related EL progenies for phenological growth traits, a better timing of the growth rhythm over the growing season together with a greater growth efficiency allowed for a consistently positive heterosis over EL. The situation appeared more complex with JL as heterosis could be either positive or negative. Besides the high variation in heterosis levels, the way heterosis for height built up over the growing season seemed also to be variable according to genetic backgrounds: cumulative constant superiority of the hybrid for growth rhythms along the growing season or greater growth rates during discrete periods of time.

Mots clés

  • heterosis
  • phenology
  • growth
  • hybrid larch
  • Larix.
Accès libre

Estimation of Clonal Variation in Seed Cone Production Over Time in a Scots pine (Pinus sylvestris L.) Seed Orchard

Publié en ligne: 19 Oct 2017
Pages: 53 - 62

Résumé

Abstract

Possibilities for early selection of clones for future seed cone production were studied in a clonal seed orchard of Scots pine (Pinus sylvestris L.) in northern Sweden over the first 30 years following establishment. The annual data were modelled as series of bivariate analyses. The correlations between cone production of clones in any individual year and that of a previous year, and cumulative cone production over all years were studied. The corresponding multivariate analysis for a full data fit simultaneously was best estimated with a genetic distance-based power model (AR). The genetic (variation among clones) and environmental variation were of the same magnitude. The genetic correlations were larger than the phenotypic correlations and both increased with orchard age. Basing selection of clones on a single observation at an early age to improve future cone production was not effective, but efficiency increased if cumulative cone count over many years was used. Year-to-year genetic correlations indicated that early forecasts by clone of cone production at mature ages are highly uncertain. Reliable predictions (moderate correlations) could be achieved only if based on rather mature grafts, 14 or more years after establishment.

Mots clés

  • Pinus sylvestris
  • fruitfulness
  • longitudinal data
  • reproductive competence
  • broad-sense heritability.
Accès libre

Responses of Falcataria moluccana seedlings of Different Seed Sources to Inoculation With Uromycladium tepperianum

Publié en ligne: 19 Oct 2017
Pages: 62 - 68

Résumé

Abstract

Falcataria moluccana (batai) is one of the valuable multipurpose tree species for forest plantations, particularly in Malaysia and Indonesia. Gall rust disease caused by Uromycladium tepperianum (Sacc.) is one of the most destructive diseases in Batai plantations. The disease causes severe damage at all developmental stages of the plant from the nursery stage to mature trees in the field and includes the development of chocolate brown, cauliflower-like or whip-like galls on the stem, branch, petiole, shoot and pod. Different seed sources may respond differently to gall rust fungus. Thus, the responses of F. moluccana seedlings from 6 selected seed sources to gall rust disease caused by U. tepperianum, were evaluated, at the Brumas Estate, Malaysia, in terms of gall rust disease severity, mortality, and disease infection rate of the seedlings. Based on disease severity, infection rate and cumulative mortality due to gall rust disease, the wamena was found to be the best seed source in relation to gall rust disease resistance.

Mots clés

  • Falcataria moluccana
  • seed sources
  • Uromycladium tepperianum
  • artificial inoculation
  • resistance.
Accès libre

Characterization of Juglans nigra (L.), Juglans regia (L.) and Juglans x intermedia (Carr.) by SSR markers: a case study in Italy

Publié en ligne: 19 Oct 2017
Pages: 68 - 78

Résumé

Abstract

Juglans nigra and Juglans regia are economically important species in Europe, Asia and North America. Natural hybrids between the two species, known as Juglans x intermedia (Carr), are valued for timber production. We tested ten nuclear microsatellite markers to (1) identify new J. x intermedia hybrids and characterize their parentage species J. regia and J. nigra (2) detect J. nigra genotypes with a spontaneous crossing ability with J. regia in a mixed Italian population. This study was also designed to confirm the transferability of ten black walnut SSR loci to Persian walnut All ten microsatellites amplified in both species, producing fragments of variable size; eight (7.14%) were common, 68 (60.7%) amplified in J. nigra and 36 (32.1%) in J. regia only (private alleles). Indices of genetic diversity revealed high level of variability. The Principal Coordinate Analysis on the basis of total 112 alleles divided the total sample set into three main groups: J. nigra, J. regia and J. x intermedia hybrids. Performing the microsatellite fingerprinting, a triploid hybrid plant with two genome parts of J. nigra and one part of J. regia was identified. The cytological analysis proved this triploid state showing 48 somatic chromosomes. The mother testing analysis of the 7 diploid hybrids by exclusion method indicated one putative hybridogenic mother plants. The sequence analysis of amplified fragments confirmed the cross-species amplification of SSR. Inter-specific differences between alleles were due not only to simple changes in the number of repeats but also to mutations in the flanking regions.

Mots clés

  • Juglans
  • interspecific hybrids
  • microsatellites
  • cross-species amplification
  • sequencing.
Accès libre

Genetic Variation and Structure of native and introduced Casuarina equisetifolia (L. Johnson) Provenances

Publié en ligne: 19 Oct 2017
Pages: 79 - 85

Résumé

Abstract

Casuarina equisetifolia is an important tree species in tropical/subtropical zones of Asia, the Pacific and Africa. In this study, 220 individuals from seven native provenances and eleven introduced provenances of C. equisetifolia were analyzed to assess the genetic variation and structure using amplified fragment length polymorphism (AFLP) markers. A total of 465 bands were obtained by eight primer pairs, among which 153 were polymorphic. The mean NEI’s gene diversity H = 0.2113 calculated for 18 provenances and the total gene diversity HT = 0.4065 calculated for native provenances suggested abundant variation within provenances and species. High genetic divergence coefficient (GST = 0.4737) and low gene flow (Nm = 0.5555) detected among native provenances suggesting high differentiation of C. equisetifolia. An AMOVA analysis for native provenances revealed a high proportion (46.07%) of the total genetic variation distributed among provenances. The UPGMA clustering (r = 0.8028) and the Mantel test (r = 0.0716) for native provenances showed there was no correlation among genetic relationships and geographical distribution. The genetic information provided important implications for the future conservation and breeding programs of C. equisetifolia.

Mots clés

  • Casuarina equisetifolia
  • AFLP markers
  • genetic variation
  • genetic structure
  • native range
  • introduced range.
Accès libre

Annual Fertility Variation in Clonal Seed Orchards of Teak (Tectona grandis L.f.) and its Impact on Seed Crop

Publié en ligne: 19 Oct 2017
Pages: 85 - 93

Résumé

Abstract

Fertility variation was studied in two clonal seed orchards (CSO) of teak in four consecutive years (2003-2006). Both orchards were raised in 1976 with grafts of phenotypes selected for growth and form. The seed orchards of CSO I (Topslip, Tamil Nadu State) and CSO II (Walayar, Kerala State) have 15 and 20 clones, respectively, with 13 common clones. The proportion of flowering ramets was generally low ranging from 16 to 53% across years. The best fruit yield during the study period was around 18 kg ha-1 in CSO I and 17 kg ha-1 in CSO II. Highly significant clonal variation and clone by year and clone by site interactions were observed for fertility traits. The clonal contribution was more skewed in poor flowering years than in abundant flowering years and in CSO II than in CSO I. Broad sense heritability for flower and fruit production per tree was low to moderate (0.16 to 0.55). Flower and fruit production by individual ramets in successive years were positively correlated. Correlations between reproductive and growth traits were generally low, but correlation was strong between flowering and fruiting. Fertility variation and group coancestry were higher in poor flowering years than in abundant years and in CSO II than CSO I. Restricting seed collection to abundant flowering years, adjusting ramet number to balance contribution of clones and mixing of seeds from successive years are suggested to reduce relatedness among orchard progeny. The usefulness of low input breeding options for teak like seed production areas are also discussed.

Mots clés

  • Flowering
  • fruit production
  • diversity
  • coancestry
  • heritability
  • status number.
Accès libre

Short Note: Internal Size Standard for Microsatellite Genotyping

Publié en ligne: 19 Oct 2017
Pages: 94 - 96

Résumé

Abstract

The in-house production of fluorescently labelled

internal size standard offers the advantage of cost saving

over the commercial size standard in microsatellite

genotyping. Based on the reported in-house internal size

standard protocol, we have improved the method by generating

21 DNA fragments (in a standard named as HM-

400) with each size similar to that of the commercial

size standard. The consistent amplification of the correct

fragment size was optimised via primer modulation

for non-templated nucleotide addition by Taq DNA polymerase.

A total of six microsatellite loci were used to

assess the accuracy of HM-400 and the mean standard

deviation of the size data was 0.19. The differences

between the fragment size means for samples sized

using HM-400 and commercial size standard were small

with an average of 0.29 bp. The production cost of HM-

400 was only 10% of the cost of commercial size standard.

Mots clés

  • size standard
  • microsatellites
  • genotyping
  • population genetics
  • dipterocarps.
Accès libre

Inheritance Pattern of Growth and Wood Traits in Teak (Tectona grandis L.f.).

Publié en ligne: 19 Oct 2017
Pages: 97 - 101

Résumé

Abstract

Inheritance pattern of wood traits, especially heartwood/ sapwood percentage and specific gravity and interactions of wood traits with other growth traits were investigated in a 27-year-old half-sib progeny trial of teak. Wood traits showed highly significant variation for specific gravity, heartwood and sapwood percentage at family level. There was non-significant family vs. replication variation for these traits. Among the growth traits, there was significant variation for height and girth. Families and individual trees showed varying levels of heritability. Among the growth traits, height showed high heritability (individual tree heritability, h2 (i) = 34.3%; family heritability, h2 (f ) = 34.1%) followed by girth (h2 (i) = 19.4%; h2 (f ) = 31.4%). Among the wood traits, maximum heritability values were obtained for sapwood percentage (h2 (i) = 76.6%; h2 (f ) = 70.7%) and heartwood percentage (h2 (i) = 76.9%; h2 (f ) = 69.7%). Specific gravity exhibited heritability values of 29.1 and 41.8%, at individual tree and family level, respectively. Family heritability was higher than single-tree heritability for specific gravity; single-tree heritability exceeded family heritability for heartwood percentage. Specific gravity exhibited significant positive genotypic correlation with heartwood percentage suggesting that improvement in heartwood percentage would lead to a correlated improvement in specific gravity. Heartwood percentage showed significant positive correlation with growth traits viz., height and girth. Some of the families showed good GCA for growth and wood traits investigated. The good general combiners identified in the present study can be used for establishment of advanced generation seed orchards and breeding arboreta for improvement of teak for specific or combination of above traits.

Mots clés

  • Inheritance pattern
  • half-sib progeny trial
  • heritability
  • heartwood percentage
  • sapwood percentage
  • height
  • girth
  • specific gravity
  • general combining ability
  • genetic gain.
Accès libre

Determining the Optimal Age For Selection by Modelling the Age-Related Trends in Genetic Parameters in Eucalyptus Hybrid Populations

Publié en ligne: 19 Oct 2017
Pages: 102 - 112

Résumé

Abstract

Ten factorial mating designs using a combined total of 88 females, 107 males, 684 families and 37,206 individual trees were used to model the age-related trends in genetic parameters and genetic gain between four and 65 months in the Eucalyptus urophylla x grandis breeding population in Republic of Congo. Selection was either of pure species (as parents for continued breeding) or individual hybrids for commercial plantations based on clonal varieties. The variance components were significantly different from zero for female, male and female-by-male interaction effects for volume. The age-related trends in additive, dominance and environmental variances, modelled by nonlinear functions, showed three phases corresponding to different stages of competition and growth. Male and female narrow sense heritabilities were high (h2 Am= 0.70 and h2 Af = 0.90, respectively for highest estimates) compared with individual broad sense heritability (h2 ind= 0.45). They were modelled by polynomial functions that did not display specific trends with age. The age-age correlations, modelled by a response surface, were higher than 0.8 after 36 months. A similar trend with age was observed for additive and total genetic effects. Genetic gain was calculated by combining the different models. The genetic gain was higher for female than for male. Considerable gains can be achieved by clone selection. The efficiency of selection indicated an optimal age of 54 months for juvenile selection of males and females and a mature age for ortets. The trend in efficiency of selection per time unit showed that juvenile selection for volume is much more efficient than adult selection whatever the age.

Mots clés

  • Eucalyptus
  • volume
  • reciprocal recurrent selection
  • variance components
  • heritability
  • age-age correlation
  • optimal age of selection.
Accès libre

Genetic Parameters and Genotype by Environment Interactions for Green and Basic Density and Stiffness of Pinus radiata D. Don Estimated Using Acoustics

Publié en ligne: 19 Oct 2017
Pages: 112 - 122

Résumé

Abstract

Genetic parameters and genotype by environment interactions for wood properties of 13-year-old Pinus radiata were determined by sampling two progeny trials on contrasting sites in the southern slopes of New South Wales, Australia. Heritability of green and basic density were determined together with dynamic modulus of elasticity (MOE) measured using TreeTap. The phenotypic variance in MOE (CV 17-18%) was almost three times that of basic density. MOE and basic density were highly heritable at both sites (h2 0.57 & 0.79 for MOE & 0.59 and 0.85 for density). There was a moderately strong genetic correlation between MOE and basic density (0.64 across-sites). No genotype x environment interaction was detected in MOE or basic density. Basic density and MOE were lower on the warmer, lower rainfall site.

Mots clés

  • Pinus radiata
  • standing tree acoustic tools
  • dynamic modulus of elasticity
  • basic density
Accès libre

Agrobacterium tumefaciens-mediated Transformation of Jatropha curcas: Factors Affecting Transient Transformation Efficiency and Morphology Analysis of Transgenic Calli

Publié en ligne: 19 Oct 2017
Pages: 123 - 128

Résumé

Abstract

An efficient system for Agrobacterium tumefaciensmediated transformation of Jatropha curcas was developed in this study. Several factors affecting the transformation efficiency were optimized, including the explant type, preculture and coculture periods, usage of acetosyringone and density of A. tumefaciens. Compared with other explants, 2-day precultured and cocultured hypocotyl explants showed a significant GUS transient expression efficiency (67.7%). Moreover, adding AS showed a remarkable increase in transformation efficiency. After infecting with A. tumefaciens, hypocotyl explants were subjected to expansion and proliferation on MS medium with 1.0 mg· l-1 IBA and 0.5 mg· l-1 BA. Transformants were demonstrated by the GUS assay and PCR analysis. Rate of hypocotyl explants forming resistant calli reached 67.08%. Furthermore, in the transformed calli development, morphologic changes (calli superficial development and internal structure) were observed by SEM and LM. The present study has provided a fundamental information and research approach for the future study of inducing new traits to J. curcas and genetic modification.

Mots clés

  • Jatropha curcas
  • Agrobacterium tumefaciens-mediated transformation
  • light microscopy
  • scanning electron microscopy.
Accès libre

The Relative Contribution of The Male and Female to The Variation in Reproductive Success in Eucalyptus globulus

Publié en ligne: 19 Oct 2017
Pages: 129 - 138

Résumé

Abstract

Low and variable capsule and seed set is a major factor limiting seed production in Eucalyptus globulus seed orchards. This study identified the relative contribution of the maternal and paternal parent to reproductive success in E. globulus, and examined the genetic basis to the observed variation. Reproductive success was measured in terms of the number of viable seeds obtained per flower crossed. Data on the reproductive success of numerous genotypes from the Furneaux, Strzelecki Ranges and Otways races were obtained from: (i) 12 years of operational full-sib crossing; (ii) a designed fullsib diallel mating scheme; and (iii) capsule retention trials conducted over three seasons at two Tasmanian seed orchards on the same ramets of different genotypes. Analysis of the sparse operational data revealed that both male and female factors significantly affected reproductive success, accounting for 5.0% and 7.9% of the variation respectively. The more precise diallel crossing revealed that a large, and significant, proportion 55%, of the variation in reproductive success between crosses at a single site was explained by the female parent. The male parent explained only 6.7%, but this effect was not statistically significant and was related to variation in in vitro pollen germination. The significant female effect was found to be consistent at the genotype level across seasons, sites and pollination techniques suggesting a genetic basis to the variation. It is argued that selection of genetically fecund females is a key consideration in reducing costs of manual pollination for breeding and deployment purposes.

Mots clés

  • Eucalyptus globulus
  • capsule set
  • seed set
  • capsule abortion
  • reproductive success
  • mating system
  • parental contribution.
Accès libre

The Contribution of Pollen Germination Rates to Uneven Paternity Among Polycrosses of Cryptomeria japonica

Publié en ligne: 19 Oct 2017
Pages: 139 - 144

Résumé

Abstract

Polycrossing is a very useful and cost-effective approach when designing mating trials. However, since the maternal general combining ability (GCA) in polycross designs is estimated on the assumption of equal contributions from paternal parents; any unequal paternal contribution leads to biased GCA estimates. Progeny from polycrossing Cryptomeria japonica, in which three mixtures from three paternal donors were crossed with each of three maternal parents, were analyzed using microsatellite markers to detect departures from equal paternal contribution. The deviations from equal paternal contribution were evaluated using a χ2 goodness of fit test. In this test, we examined the null hypothesis of equal paternal contribution for each mother tree. Two different methods were used to calculate paternal contribution: first, simply the number of seeds produced by each male parent, and second, the number of seeds produced by each male parent weighted according to the proportion of full seeds in single cross. The results of the χ2 test showed that the contribution to seed production by each paternal clone differed significantly in all polycrosses. The average pollen germination rate was significantly different between paternal clones. The contribution of each pollen donor in a polycross was related to their pollen germination rate.

Mots clés

  • Male reproductive success
  • Paternal success
  • GCA
  • Molecular marker
  • Polymixes.
Accès libre

The Impact of Phenological and Artificial Factors on Seed Quality in a Nematode-resistant Pinus densiflora Seed Orchard

Publié en ligne: 19 Oct 2017
Pages: 145 - 152

Résumé

Abstract

To clarify the relationship between the impact of phenological and/or artificial factors on seed quality, we measured the numbers of strobili on nematode-resistant Pinus densiflora clones grown in an immature and relatively small scale (700 m2) seed orchard. In addition, we established the clonal identities of all ramets, identified the paternal parent of the seeds, and assessed the resistance of seedlings to nematode infection. We also clarified the quantitative differences of strobili among clones; one clone produced 86.4% and 70.8% of all male strobili and female strobili, respectively. However, given that the total contamination ratio of the orchard was 82.0%, immigrant pollen had a larger impact on the success of actual crossing than phenology. Seedlings with a resistant maternal parent were resistant, even when their paternal parent was from outside the orchard. Two unselected clones were also planted in the seed orchard, one of which was not resistant and was associated with a maternal contribution of 34.7% of all seed stock. These findings suggest that, despite having a large impact on the crossing, immigrant pollen has a minor impact on seed resistance. Conversely, unselected and nonresistant clones have a marked impact on seed resistance. We concluded that artificial factors have larger impact on the seed quality than phenological factors in this orchard and the seeds will be of sufficient quality for supplying the market once nonresistant clones have been removed from the orchard.

Mots clés

  • nematode resistant
  • Pinus densiflora
  • pollen contamination
  • resistant ability
  • seed orchard
  • seed quality
  • SSR marker.
Accès libre

Genetic Variation in Seed Size and Germination Patterns and their Effect on White Spruce Seedling Characteristics

Publié en ligne: 19 Oct 2017
Pages: 152 - 161

Résumé

Abstract

We determined the degree to which families differ in seed and germination characteristics and examined the extent to which these characteristics influence the early growth of 75 open-pollinated white spruce families. Seed characteristics (1000-seed weight, length, width, area, volume) were measured for 400 seeds per family. Germination variables (germination capacity, peak value, germination value) were determined for each of the 75 families under controlled conditions and germination patterns were modelled using the Weibull function. Seedling characteristics (height, diameter, shoot and root dry weights) were measured at the end of the first and second growing seasons under standard nursery cultural practices. Statistically significant family variation (p < 0.0001) was found for all seed characteristics and germination variables measured. The between-family variance explained 23% to 98% of the total variance of morphological and physiological seed characteristics. Family differences at the seed stage explained up to 33% (root dry weight) and 12% (shoot dry weight) of the family differences observed at the one-year and two-year seedling stages, respectively. Since, in this study based on a comparison of family means, a maximum of only 12% of the family differences observed at the two-year seedling stage were explained by the effect of seed size, a selection for families with better juvenile characteristics could be envisaged without considering the maternal effect of seed size.

Mots clés

  • Weibull function
  • genetic variation
  • repeatability
  • heritabilities
  • maternal effect
  • Picea glauca.
Accès libre

Effects of Cryoprotectants and Post-storage Priming on Seed Germination of Sugi (Cryptomeria japonica

Publié en ligne: 19 Oct 2017
Pages: 162 - 168

Résumé

Abstract

Among the ex situ methods for the preservation of forest tree germplasm, conventional seed banking is considered the most efficient method for the majority of species whilst cryopreservation has an important role in long-term conservation. The influence of cryoprotectants prior to liquid nitrogen (LN) storage and osmoconditioning priming treatments with polyethylene glycol (PEG) after LN storage were evaluated for germination (%), germination value (GV) and mean germination time (MGT) in seeds of Cryptomeria japonica. Sugi seeds were treated with two cryoprotectants (DMSO and PVS2) before immersion into LN and stored for three days. Although the C. japonica seeds survived liquid nitrogen treatment, their viability was reduced from 25% of intact seeds to 17% in LN. The seeds treated with 35% DMSO showed higher germination (28%) as compared with seeds directly-immersed in LN without cryoprotectant treatment. In contrast, PVS2 pretreated seeds decreased germination (13%). Two concentrations of PEG priming treatments were carried out. Osmoconditioning treatment in -0.4 MPa PEG solution after removal from LN enhanced the subsequent germination percentage and decreased MGT. PEG treatments at both -0.4 and -1.2MPa to PVS2 pretreated seeds before cryopreservation partially alleviated the negative effect of PVS2. DMSO pretreated seeds immersed into LN and treated with -0.4MPa PEG maintained the 28% of germination obtained in the control conditions and reduced the mean germination time (MGT). It can therefore be summarized that pretreatment with 35% DMSO was suitable for the cryopreservation of C. japonica seeds whilst the PEG priming treatment circumvented imbibitional damage after LN exposure.

Mots clés

  • Cryptomeria japonica
  • seed storage
  • liquid nitrogen
  • cryoprotectant
  • DMSO
  • PVS2
  • priming
  • cryopreservation
  • ex situ conservation.
Accès libre

Identification and Characterization of Microsatellite Markers Useful for Genetic Analysis of Black Spruce (Picea mariana (Mill.) Populations

Publié en ligne: 19 Oct 2017
Pages: 168 - 172

Résumé

Mots clés

  • Picea mariana
  • black spruce
  • microsatellites
  • upland
  • lowland
  • polymorphism.
Accès libre

Phenotypic Selection of Calycophyllum spruceanum on Farms in the Peruvian Amazon: Evaluating a Low-Intensity Selection Strategy

Publié en ligne: 19 Oct 2017
Pages: 172 - 179

Résumé

Abstract

A low-intensity selection strategy was recommended for timber trees in the Peruvian Amazon to maintain genetic variation on farms and produce modest gains in tree growth. The effectiveness of this strategy was evaluated using Calycophyllum spruceanum. Farmers selected 66 mother trees of different ages on farms in seven locations (~20% of all trees in the locations) in one watershed, based on a visual assessment of growth, form and external disease symptoms. Another 66 mother trees were chosen at random. Tree height, stem diameter, stem bifurcations and mortality of progeny of the selected and random groups of mother trees were evaluated at 15, 26 and 38 months in a provenance/progeny test located on farms in the same watershed. Height was significantly greater (10%) in the selected group at 15 months, but it did not differ significantly between the selected and random groups at 26 and 38 months. There were no significant differences in diameter, bifurcations and mortality between the groups. There was significant variation in height and diameter at all measurement ages due to families, and results suggested that variation in bifurcations and mortality due to families was also significant. Based on approximate 95% confidence

intervals, family variances in height and diameter did not differ significantly between the selected and random groups at any measurement age, but evaluations should continue to confirm these tentative conclusions. Some practical implications for tree improvement programs are discussed.

Mots clés

  • tropical timber tree improvement
  • genetic variation
  • growth
  • form
  • mortality.
Accès libre

Growth, Form and Quambalaria Shoot Blight Tolerance of Spotted Gum in North-eastern New South Wales, Australia

Publié en ligne: 19 Oct 2017
Pages: 180 - 191

Résumé

Abstract

A young provenance/progeny trial of spotted gums, which are major hardwood plantation species in subtropical eastern Australia, was studied for growth, form, and damage from Quambalaria shoot blight. The trial contained a wide range of genotypes, mainly of Corymbia citriodora subsp. variegata, with between one and 21 families per provenance. Genetic parameters were calculated from 23 provenances with four or more families. Provenances superior for growth included four well-represented C. citriodora subsp. variegata provenances, all from south-east Queensland, which also had a high proportion of superior families. Overall, Queensland provenances had significantly higher mean diameter and height than those from New South Wales (NSW), although there were several superior NSW families. Provenances superior for growth also displayed good straightness and relatively fine branching. Relatively low Quambalaria shoot blight damage was recorded for four Queensland provenances and one coastal NSW provenance, which all had high proportions of families with low damage. Provenances that were putative intergrades between C. citriodora subsp. variegata and C. maculata tended to have high damage levels. However, some mediocre provenances contained superior families potentially useful for breeding. Regressions of Quambalaria damage index (QDI) on latitude, and mean height growth on QDI, were highly significant and moderately strong (0.51 and 0.58, respectively), indicating increasing damage in more southern material, and a retarding effect (although not striking) of damage on growth. Individual heritability estimates were low (zero to 0.14) for growth and form, and moderate for QDI (0.31). The genetic correlations for QDI with growth traits were strong and negative (-0.77 and -0.88), supporting a strategy of selecting vigorous trees for breeding programs from provenances and families superior for these traits.

Mots clés

  • Spotted gum
  • Corymbia
  • Quambalaria pitereka
  • Quambalaria shoot blight
  • growth
  • form
  • genetic relationships
  • provenance trial
  • family trial.
Accès libre

Genetic Variation Amongst and Within The Native Provenances of Pinus radiata D. Don in South-eastern Australia. 2.Wood Density and Stiffness to Age 26 Years

Publié en ligne: 19 Oct 2017
Pages: 192 - 204

Résumé

Abstract

Two progeny trials of native provenances of Pinus radiata, representing the 1978 seed collection, were assessed for wood density and standing tree acoustic velocity. One trial, planted in 1980 in southern New South Wales, Australia contains all five provenances. The second trial, planted in the same region in 1982 contains only the island provenances. Results for extracted wood density, assessed from pith to bark in 5 ring segments, and standing tree acoustic velocity, measured at age 24 or 26 years, are reported. Large differences between the mainland and island provenance were apparent for wood density and stiffness. The mainland provenances were very similar for density and followed the “normal” pattern of change with a gradual increase from the pith, followed by a plateauing around age 20. Neither of the island provenances followed this pattern of change in density: Cedros had stable density across the 4 inner most segments and Guadalupe had stable density for the inner two segments followed by a linear increase. Juvenile density was higher in both the island provenances than the mainland provenances. The island provenances differed from each other for standing tree acoustic velocity, with velocity being higher in Guadalupe provenance. Heritabilities for wood density and acoustic velocity (average 0.37) were higher than those for tree growth and form. Across the stem radius, heritability of density was variable with some segments having zero heritabilities in some provenances, particularly Cambria, Cedros and Guadalupe. Heritability for acoustic velocity was highest for Cambria and the island provenances. Within the mainland provenances, little difference was found between populations for either wood density or acoustic velocity. Density and standing tree acoustic velocity were negatively genetically correlated with tree diameter. Differences in provenance means were greater for acoustic velocity than for density in the outermost segment. Provenance rankings also differed, with the rankings for acoustic velocity being similar to those for density in the 2nd segment from the bark. The genetic correlations between density and velocity reached a maximum for 3rd segment. These results indicate that outerwood density is not the sole driver of acoustic velocity, and that the sound wave is perhaps not travelling through the outer most wood, but is penetrating some distance into the tree.

Mots clés

  • Pinus radiata
  • provenances
  • Californian collection
  • heritability
  • wood density
  • acoustic velocity.
Accès libre

Comparative Performance of Corymbia Hybrids and Parental Species in Subtropical Queensland and Implications for Breeding and Deployment

Publié en ligne: 19 Oct 2017
Pages: 205 - 212

Résumé

Abstract

Eighty six full-sib Corymbia F1 hybrid families (crosses between C. torelliana and four spotted gum taxa: C. citriodora subsp. variegata, C. citriodora subsp. citriodora, C. henryi and C. maculata), were planted in six trials across six disparate sites in south-eastern Queensland to evaluate their productivity and determine their potential utility for plantation forestry. In each trial, the best-growing 20% of hybrid families grew significantly faster (P = 0.05) than open-pollinated seedlots of the parent species Corymbia citriodora subsp. variegata, ranging from 107% to 181% and 127% to 287% of the height and diameter respectively. Relative performance of hybrid families growing on more than one site displayed consistency in ranking for growth across sites and analysis showed low genotype-by-environment interaction. Heritability estimates based on female and male parents across two sites at age six years for height and diameter at breast height, were high (0.62 ± 0.28 to 0.64 ± 0.35 and 0.31 ± 0.21 to 0.69 ± 0.37 respectively), and low to moderate (0.03 ± 0.04 to 0.33 ± 0.22) for stem straightness, branch size, incidence of ramicorns, and frost and disease resistance traits at ages one to three years. The proportion of dominance variance for height and diameter had reduced to zero by age six years. Based on these promising results, further breeding and pilot-scale family forestry and clonal forestry deployment is being undertaken. These results have also provided insights regarding the choice of a future hybrid breeding strategy.

Mots clés

  • Spotted gums
  • Hybrid
  • Corymbia
  • Eucalypt
  • Quambalaria
  • Breeding strategy
  • Deployment
  • Heritability
  • Genetic parameters.
Accès libre

Performance and Genetic Parameters of Somatic and Zygotic Progenies of Coastal Douglas-fir at 71/2-Years across Washington and Oregon, USA

Publié en ligne: 19 Oct 2017
Pages: 212 - 219

Résumé

Abstract

Five genetic tests involving 37 somatic clones of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were planted March 2000 in Weyerhaeuser plantations across western Washington and Oregon States, USA. Four of the tests are in Longview, Twin Harbors and Vail regions of Washington, and one test is in Springfield, Oregon. Each test is based on single-tree plots with 12 randomized complete-blocks. The 37 coastal Douglas-fir clones were propagated by somatic embryogenesis from four full-sib families. Zygotic seedlings from two of these full-sib families were planted across all five tests to allow comparison between somatic and zygotic trees of the same pedigree. Results are reported for survival, stem height, diameter at breast-height (DBH), volume and stem sinuosity at 71/2- years. On average the total population of 37 somatic clones had less stem sinuosity, but grew more slowly than zygotic trees across the five tests studied. However, the best 20% of somatic clones for growth produced 25% greater stem volume at 71/2-years than the zygotic fullsib families. Height had a clonal heritability of 0.61 ± 0.09, DBH 0.64 ± 0.06, volume 0.58 ± 0.08 and stem sinuosity 0.26 ± 0.06. The clonal genetic correlation between height and DBH at 71/2-years was 0.98 ± 0.01, while stem sinuosity was adversely genetically correlated with growth. Clonal performance for growth and stem sinuosity was stable across tests with overall between-test correlations of 0.96 to 0.98. This clonal stability resulted in little variance due to clone x test interactions.

Mots clés

  • Coastal Douglas-fir
  • somatic and zygotic trees
  • growth and form
  • clonal heritabilities
  • clonal stability.
Accès libre

Distribution of Microtubular Cytoskeletons and Organelle Nucleoids During Microsporogenesis in a 2n Pollen Producer of Hybrid Populus

Publié en ligne: 19 Oct 2017
Pages: 220 - 226

Résumé

Abstract

The distribution of microtubular cytoskeletons and organelle nucleoids during microsporogenesis in Populus simonii Carr. x P. nigra L. ‘Tongliao’ was studied by indirect immunofluorescence and 4’,6-diamidino-2- phenylindole (DAPI) staining. Our purpose was to reveal the relationship between changes in microtubule and chromosome behavior and cytokinesis and to explain the mechanism of 2n pollen production. We observed stable frequencies of 2n pollen production, ranging from 1.56% to 2.29%, between 2006 and 2008. Moreover, conjoined pollen grains were also observed. Meiotic abnormalities, including univalents, lagging chromosomes and micronuclei, were observed during microsporogenesis. Triads and dyads were also detected in meiotic products. Parallel spindles in metaphase II were unable to fuse, owing to the existence of an organelle band. Regularly, in telophase II, primary phragmoplasts were organized between sister nuclei, and secondary phragmoplasts formed between non-sister nuclei. Cell plates were initiated by centrifugal expansion of phragmoplasts and cytoplasmic infurrowing started at the junctions between the microsporocyte wall and the expanded phragmoplasts. However, a secondary phragmoplast was absent in some microsporocytes. These observations suggest that the occurrence of 2n pollen may result from the partial failure of cytokinesis caused by the absence of secondary phragmoplasts in this hybrid.

Mots clés

  • microsporogenesis
  • microtubular cytoskeleton
  • organelle nucleoids
  • Populus
  • 2n pollen.
Accès libre

A Novel Gel-based Method for Isolation of Stigmas During Controlled Pollination Experiments

Publié en ligne: 19 Oct 2017
Pages: 226 - 233

Résumé

Abstract

In forestry, controlled pollination (CP) allows the combining of genetic material of selected elite trees to produce high quality, and consequently high value, seed. The aim of the present study was to develop a novel isolation method that would allow the technique to be conducted without expensive and time-consuming bagging, making CPs on small-flowered eucalypts commercially viable. We compared the current method of isolating inflorescences using exclusion bags to a novel method which uses sodium alginate gel. Sodium alginate was effective in keeping external pollen away from the stigma, since no seed was produced in those treatments that were not manually pollinated but isolated in this way. In addition, flowers hand-pollinated and isolated with sodium alginate produced progeny that were 100% outcrossed with the applied pollen. The exclusion bags, on the other hand, were not as effective in protecting the stigma as seed was produced in those treatments that were isolated with an exclusion bag without being handpollinated. Sodium alginate isolation also increased the efficiency of control-pollinations as the gel was naturally shed, removing the need for operators to return to the tree to remove the isolation material.

Mots clés

  • control-pollination
  • bud isolation
  • sodium alginate
  • exclusion bag
  • Eucalyptus
  • Artificially Induced Protogyny.
Accès libre

Mitochondrial DNA variation in natural populations of Japanese larch (Larix kaempferi)

Publié en ligne: 19 Oct 2017
Pages: 234 - 241

Résumé

Abstract

Levels of genetic variation within and among natural populations of Japanese larch [Larix kaempferi (Lamb.) Carrière] were evaluated by Restriction Fragment Length Polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) obtained from 209 individuals representing 14 natural populations distributed across most of the species’ natural range in central Japan. Polymorphisms were screened by two RFLP techniques: Southern hybridization of mitochondrial gene probes and Polymerase Chain Reaction (PCR)-RFLP analysis of sequence-tagged sites. However, obvious polymorphism was only detected around the coxIII gene, following digestion with the EcoRI restriction enzyme, in the Southern hybridization analysis. Five haplotypes were identified across the 14 populations, with 11 populations exhibiting little or no genetic variation. Within-population genetic variation was low (HS = 0.158), while population differentiation was substantial (a standardized genetic differentiation measure, G’ST = 0.581). The northernmost, marginal population on Mt. Manokamidake made a significant contribution to the total detected genetic variation. The mtDNA variation displayed geographic structure despite the restricted natural distribution of Japanese larch. Results of this study should be useful for establishing criteria for the genetic conservation and management of natural populations of the species.

Mots clés

  • genetic diversity
  • genetic structure
  • Japanese larch
  • mitochondrial DNA
  • population differentiation
  • RFLP.
Accès libre

Genetic Variation Amongst and Within The Native Provenances of Pinus radiata D. Don in South-eastern Australia. 1. Growth and form to age 26 years

Publié en ligne: 19 Oct 2017
Pages: 242 - 252

Résumé

Abstract

Four hundred and sixty individual families of Pinus radiata, representing all provenances and populations in a 1978 seed collection, plus a local seed orchard control, were planted together in 1980 in a large trial in southern New South Wales, Australia. Provenance means and genetic parameters for growth measured at ages 3, 8 and 26 years plus stem straightness, branch angle and nodality at age 26 years are reported. Large provenance differences were apparent for all traits. The two island provenances, Cedros and Guadalupe, were significantly inferior to the mainland provenances and, due to competition effects, very few trees survived to age 26. Within the mainland provenances, the performance of Año Nuevo and Monterey was almost identical, with Cambria being less vigorous. The best performing seedlot for all traits was the local control. Differences between populations within the mainland provenances were apparent for diameter at age 26 within Año Nuevo and Cambria but not Monterey. Año Nuevo also showed population differences for stem straightness. Heritabilities for early growth were similar within Año Nuevo and Monterey but by age 26, the heritability for diameter was higher in Monterey. Within Cambria, heritabilities for growth and tree form at age 26 were close to zero. Genetic correlations between traits showed similar patterns for each of the mainland provenances, with the exception of correlations with stem straightness within Año Nuevo. Results are discussed in light of recent molecular studies of genetic architecture, levels of inbreeding in the native stands and possible effects of this inbreeding.

Mots clés

  • Pinus radiata
  • provenances
  • Californian collection
  • heritability
Accès libre

The Effects of Drying Temperature and Method of Assessment on the Expression of Genetic Variation in Gross Shrinkage of Eucalyptus globulus Wood Samples

Publié en ligne: 19 Oct 2017
Pages: 252 - 261

Résumé

Abstract

Genetic variation in wood-sample gross shrinkage and basic density was examined in a Eucalyptus globulus base population trial growing in Tasmania, Australia. Gross shrinkage, which includes all components of shrinkage including collapse, was assessed in four ways (calliper- and visually-assessed tangential shrinkage, volumetric shrinkage and radial shrinkage) on samples dried at three temperatures (22°C, 60°C and 105°C). Significant differences between subraces were observed using all measures of gross shrinkage for two or more of the three drying treatments. Furthermore, significant additive genetic variation within subraces was observed in calliper- and visually-assessed gross shrinkage under two or more of the drying treatments, with narrowsense heritabilities greater than or equal to 0.35. There was no obvious trend in heritabilities or coefficients of additive genetic variation with drying temperature. Under the 105°C drying treatment, subrace correlations among calliper-, visually- and volume-assessed gross shrinkage were positive and very strong (≥ 0.97), while these measures were less strongly correlated with radial gross shrinkage at the subrace level (≤ 0.77). Withinsubrace genetic correlations among the first three measures were also strongly positive (≥ 0.95). These high genetic correlations suggest that different drying regimes and the calliper, visual and volume methods of assessment could be used interchangeably to select for reduced tangential gross shrinkage. Estimated subrace and genetic correlations between basic density and measures of gross shrinkage were universally negative (i.e. favourable), although not all were significantly different to zero.

Mots clés

  • Heritability
  • genetic correlation
  • genotype-by-drying- regime interaction
  • drying defect
  • shrinkage
  • collapse
  • basic density.
Accès libre

Evaluation of Pollen Contamination in an Advanced Scots Pine Seed Orchard

Publié en ligne: 19 Oct 2017
Pages: 262 - 269

Résumé

Abstract

The pollination pattern in a Scots pine (Pinus sylvestris L.) seed orchard consisting of 28 clones was studied using nine microsatellite (SSR) loci. The nine SSR loci produced unique multilocus genotypes for each of the orchard’s 28 clones and allowed paternal assignment of the studied 305 seed using paternity exclusion probability of 99.9%. Fifty two percent of the studied seeds were sired by outside the orchard pollen sources (i.e., pollen contamination) and as expected, low selfing (2.3%) was detected. These results are valuable for the evaluation of the seed orchard function and the impact of contamination on the expected genetic gain.

Mots clés

  • Paternity analysis
  • Pinus sylvestris
  • pollination
  • SSR marker.
Accès libre

Population Genetic Structure of Laurus nobilis L. Inferred From Transferred Nuclear Microsatellites

Publié en ligne: 19 Oct 2017
Pages: 270 - 276

Résumé

Abstract

Species with fragmented populations and low population size often display low within-population genetic diversity and strong among-population differentiation. Laurus nobilis L. (Lauraceae), common laurel, has a scattered distribution throughout the Mediterranean, with only few autochthonous populations. Our goal was to elucidate if this species has range-wide genetic structure and if planted material can be traced back to its origin. Genetic diversity was investigated using 4 polymorphic nuclear microsatellites (nSSR) transferred from two species of Lauraceae. Sixty-six laurel trees were selected from 7 widely separated populations within the Mediterranean distribution area of the species. A total of 34 alleles (9 alleles per locus on average) were found. Mean genetic diversity within-population (Hs), was 0.558. Genetic differentiation among populations (GST = 0.243) was high compared to that of other angiosperms. Laurus nobilis can be separated into two main gene pools, one from western (Tunisia, Algeria and France) and the other from eastern Mediterranean (Turkey). The Algerian, Tunisian and French populations presented a strong genetic similarity, compatible with the fact that North African laurel populations could be recently introduced from north-western Mediterranean stock.

Mots clés

  • Laurus nobilis
  • Nuclear microsatellites
  • Genetic diversity
  • Differentiation
  • Mediterranean.
Accès libre

Transfer of Microsatellite Loci For The Tropical Tree Prunus africana (Hook. f.) Kalkman

Publié en ligne: 19 Oct 2017
Pages: 276 - 279

Résumé

Abstract

Using databases of previously published primers, we optimised six nuclear microsatellite markers for Prunus africana for the purposes of studying spatial genetic structure and gene flow. To assess variability, these and three previously transferred loci were screened in populations from Kenya and South Africa. Across both populations most loci were polymorphic, with the exception of a single locus which failed to amplify in the South African samples, exhibiting between 2 and 22 alleles and levels of expected heterozygosity (He) ranged from 0.059 to 0.932. Departures from Hardy-Weinberg equilibrium were detected for all loci but not for all populations. The estimated null allele frequency was very low to moderate and no evidence for linkage disequilibrium was detected.

Mots clés

  • Prunus africana
  • nuclear microsatellites
  • gene flow
  • genetic diversity.
Accès libre

Genetic Diversity of an Australian Santalum album Collection – Implications For Tree Improvement Potential

Publié en ligne: 19 Oct 2017
Pages: 279 - 286

Résumé

Abstract

The Forest Products Commission of Western Australia manages a sandalwood (Santalum spp.) core germplasm collection at Kununurra in the states far north. This collection serves as a significant seed source for sandalwood plantations in the area and remains an important resource for ongoing research. The collection contains S. album trees sourced from Indian arboreta, along with a few trees from West Timor, Indonesia. Also present are representatives of S. macgregorii from Papua New Guinea and S. austrocaledonicum from Vanuatu and/or New Caledonia. Despite the apparently diverse seed origins, the genetic background of many of the accessions remains vague. In this study, diversity and relatedness was assessed by nuclear and chloroplast RFLPs and a phylogeny was inferred. Nuclear RFLPs revealed very low levels of genetic diversity for a tree species, with an observed and expected heterozygosity (Ho and He) of 0.047. Nineteen genotypes were identified within the 233 S. album individuals sampled, with only one tree known to have originated from Timor being differentiated from Indian material. Other trees thought to have come from Timor grouped with those believed to be from India, indicating they were either incorrectly labelled or sourced from heavily modified populations. Despite the poor sample size, chloroplast RFLP analysis revealed no genetic distinction between the Timorese and Indian S. album, which supports the theory of human mediated seed dispersal from Timor to India. The structure of the phylogeny and associated relatedness has assisted in the establishment of seed orchards, designed to ensure maximum diversity is maintained through limiting the proximity of highly related trees. Finally, in light of these and other findings, a hypothesis concerning the evolution of S. album is proposed.

Mots clés

  • Sandalwood
  • Santalum
  • genetic diversity
  • phylogeny
  • evolution.
Accès libre

DNA Methylation in Acacia mangium In vitro and Ex-vitro Buds, in relation to their Within-shoot Position, Age and Leaf Morphology of the Shoots

Publié en ligne: 19 Oct 2017
Pages: 287 - 292

Résumé

Abstract

DNA methylation was analyzed in Acacia mangium Willd. buds collected from in vitro and field growing shoots from the same clone and its juvenile offspring. Shoot tips from in vitro microshoots showed higher levels of DNA methylation for juvenile (23.4%) than for mature (21.8%) plant material, irrespective of their morphology. Likewise, under the same in vitro conditions, the apical buds collected from microshoots exhibiting the juvenile morphology displayed higher DNA methylation rates (23.2%) than those characterized by the mature phyllode morphological type (22.1%), regardless of the age of the plant material source. In outdoor conditions, apical buds collected from mature tree growing shoots were significantly less methylated (20.9%) than the resting axillary buds located just underneath (25.2%) and than the apical buds from the in vitro microshoots of the same clone and mature-like phyllode morphology (22.6%). Overall, the DNA methylation levels found for our Acacia mangium plant materials were consistent with those reported for other Angiosperms, but showed, similarly to other recent findings in different species, that DNA methylation in plants does not always increase with ageing. This was discussed in relation to other phase-related traits and more particularly foliage characteristics, which are conspicuous markers of ageing in this heteroblastic species.

Mots clés

  • Acacia mangium
  • Ageing
  • DNA methylation
  • In vitro
  • Morphological markers
  • Within-shoot position.
Accès libre

Efficiencies of Clonally Replicated and Seedling Testing for Spruce Breeding and Deployment Strategies

Publié en ligne: 19 Oct 2017
Pages: 292 - 300

Résumé

Abstract

Genetic gains based on a genetic test using clonal replicates were compared to those based on a test using seedlings at the same gene diversity and testing effort levels using POPSIM™ Simulator. Three testing and deployment strategies targeting for white spruce (P. glauca [Moench] Voss) and black spruce (P. mariana (Mill.) B.S.P.) in New Brunswick were compared: seedling test with clonal seed orchard deployed as seedlings (CSO_ST), clonally replicated test with clonal seed orchard deployed as seedlings (CSO_CRT), and clonally replicated test deployed as a clone mix (MVF). The breeding populations (BP) were formed by balanced within-family selection and the production populations (PP) were selected by strong restriction on relatedness, i.e., no parent in common. Compared to the seedling test, the clonally replicated test resulted in faster accumulation of additive effects but quicker loss of additive variance in the BP, and this is particular true in the case of lower narrow-sense heritability or less non-additive genetic variance. The quicker loss in BP additive variance was overcompensated for by its faster accumulation in BP additive effect, resulting in higher gain in the clonally replicated test based PPs. Compared to the CSO_ST, the gain superiority of the CSO_CRT increased with generations, decreasing narrow-sense heritability or reducing the amount of non-additive variance. Implementing MVF was the most effective in terms of gain in most simulated cases and its superiority over the CSO_ST increased with generations, decreasing narrowsense heritability, or increasing non-additive genetic variance. Overall results demonstrated significant advantages of using clonally replicated test both for BP advancement and PP selection in most of the scenarios, suggesting that clonally replicated test should be incorporated into current spruce breeding strategies.

Mots clés

  • breeding population
  • production population
  • multivarietal forestry
  • clonal seed orchard
  • genetic gain
  • status number.
38 Articles
Accès libre

Genetic Variation in Growth Curve Parameters of Konishii fir (Cunninghamia lanceolata (LAMB.) HOOK. var. konishii)

Publié en ligne: 19 Oct 2017
Pages: 1 - 10

Résumé

Abstract

Cunninghamia konishii is the island race of the species complex C. lanceolata, and is native to Taiwan. It is a valuable timber species. A comprehensive provenance- family test was established in 1973. Height and diameter were measured periodically until age 26, which was close to the species’ harvest age of about 30. These data offered an opportunity to examine the species’ growth characteristics by fitting asymptotic growth functions. We adopted the concept of repeated measures data analyses, i.e., a combination of variance component analysis and growth curve fitting, the latter involved fitting the individual tree height and diameter data to a Weibull-based function. A severe typhoon in 1996 caused serious damage to the plantation, mostly to tree heights. To prevent this damage from influencing our results, we limited the analyses to those trees judged relatively free of typhoon damage, and focused on the diameter growth data. Fitting a Weibull function with parameters a, b, and c was statistically successful (e.g. the mean R2 for diameter was 0.98). Both analyses indicate substantial variation among provenances and families, and thus opportunities for genetic selection and breeding. We particularly expound on the practical applications of growth curve fitting as an analytical tool for elucidating the mechanistic process of tree growth to assist decisions on the age for selection, even retrospectively, and modeling the response of tree growth to future climate.

Mots clés

  • Cunningham lanceolata var. konishii
  • provenance
  • repeated measures
  • growth curve fitting
  • Weibull function.
Accès libre

Genetic Parameters of Growth Traits and Wood Density in Eucalyptus grandis Progenies Planted in Argentina

Publié en ligne: 19 Oct 2017
Pages: 11 - 19

Résumé

Abstract

To determine the genetic parameters of growth traits and wood density (estimated by Pilodyn penetration) in a population of Eucalyptus grandis formed by families from 11 seed origins in NE Queensland, Australia and a local land race, 8.5-year-old progenies established in three sites in NE Argentina were evaluated. Local trees exhibited higher growth rate at two sites and better stem form, but also deeper Pilodyn penetration, at all sites; thus, there is potential to infuse new genetic variation into the current breeding population in the region. A significant amount of genetic variation was found for all traits assessed, with growth traits [diameter (DBH), height (HT) and volume (VOL)] showing different genetic structure and degree of genetic control as compared to stem straightness (FORM), bark thickness (BARK) and Pilodyn penetration (PILO). The effect of origin was negligible for growth traits while it was important for the other traits, so it should be considered in the selection strategy; in addition, individual heritability for growth traits (0.11-0.16 in the combined analyses) was generally lower than for the other traits (0.20-0.35). Genetic correlations between sites for all traits were high enough to indicate that genotype-environment interaction would not affect the selection program by using a single breeding population for this region. Genetic correlations between growth traits were high (rg > 0.80), and negligible between these and FORM; the only unfavorable genetic correlation was between PILO and BARK (rg = -0.44). Age-age correlations for growth traits and FORM were very high (rg > 0.90). Results suggest that all traits evaluated could be handled in a breeding program, either independently or combined, without negative correlated effects. Early selection for growth traits and stem form is also possible, with major savings in time.

Mots clés

  • Heritability
  • genetic correlation
  • age-age correlation
  • genetic stability
  • variance components
  • Pilodyn.
Accès libre

Genetic Diversity in Kenyan Populations of Acacia senegal (L.) Willd. Based on ISSR Markers

Publié en ligne: 19 Oct 2017
Pages: 20 - 28

Résumé

Abstract

Acacia senegal (L.) Willd is an African arid and semi arid zones, leguminous multipurpose tree species belonging to the subfamily Mimosoideae, family Fabaceae and subgenus Aculeiferum, highly valued for gum arabic production. Patterns of genetic diversity of this important species in Kenya have not been studied for efficiency of germplasm utilization, conservation and improvement. Four natural populations of A. senegal in Kenya (Bulla Sambul, Kutulo, Wamba and Meisori) were analyzed to estimate genetic variation among and within populations, by use of ISSR (Inter-simple sequence repeat) markers. Using five primers, 17 polymorphic loci were observed, ranging in size from 564bp to 983bp. A high mean total genetic diversity index for the species was observed (H= 0.27). The principal coordinates analysis (PCoA) of the 95 samples from the four populations showed that about 40.75% of the total variation was described by the first two axes with much overlap among populations; hence populations were not defined on the basis of geographic distance. Much of the genetic variation resided within the populations based on the coefficient of gene differentiation (Gst = 0.0573) and Analysis of Molecular Variance (AMOVA) (95%). It was therefore recommended that selection for the desired important economic traits for improvement and conservation should emphasize on individual trees within populations rather than among populations, and also ensure a comprehensive coverage of the entire ecological amplitude of the populations.

Mots clés

  • Acacia senegal
  • genetic diversity
  • ISSR
  • multipurpose
  • Kenya
  • differentiation
  • population
  • geographical structuring
  • selection
  • conservation.
Accès libre

A New Breeding Strategy for Pinus radiata in New Zealand and New South Wales

Publié en ligne: 19 Oct 2017
Pages: 28 - 38

Résumé

Abstract

A new breeding strategy is presented for the Radiata Pine Breeding Company, a New Zealand based research consortium, that drives the breeding program for Pinus radiata for both the New Zealand and New South Wales based Australian forest plantation industry. The new strategy builds on the existing base for P. radiata, and on the last strategy review in 2000. The new strategy comprises a large open-pollinated (OP) Main Population (MP) with 500 female parents and two sublines (250 female parents per subline). The MP will be tested using alpha designs, single-tree plots and incomplete blocks to maximise efficiency. Each subline will be tested on four sites, geographically distant from the other subline. The MP will be managed in discrete generations. Selection of the next generation will be using a combination of backward and forward selection, but the strict control of inbreeding with identified lineage will rely on the development of parental reconstruction for OP progeny. There are alternatives to this, however, such as estimating the group coancestry and accepting some additional increase in inbreeding. This is a new and significant departure from previous breeding strategies for P. radiata in New Zealand. There will also be a single, small Elite Population (EP), tested 50% as progeny and 50% as clones. Twenty four parents will be tested each year as clones and 24 as seedling progeny with some overlap between the two. It is expected that the clonal population will capture the greatest gains in traits with low heritabilities, and the half-sib progeny will capture the greatest gains in traits with high heritabilities. The two sublines will be maintained in the EP, and breeding will be managed as a rolling front with trials established every year, while trials of the MP will be established every 10 years.

Mots clés

  • Australia
  • clones
  • genetic gain
  • sublining
  • mating system.
Accès libre

Short Note: Genotype-Environment Interactions for Coastal Douglas-fir Grown to 21 Years Across Western Washington State, USA

Publié en ligne: 19 Oct 2017
Pages: 39 - 42

Résumé

Abstract

This study involves polymix families of coastal Douglas- fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) that were created by crossing parents selected from the Cascade, Longview, Twin Harbors and Vail wild populations of western Washington State. Eight to 10 female parents from each population were crossed using pollen-mixes of males from either the same or different populations. In 1985 these polymix families were planted across six genetic tests located in Cascade, Longview and Twin Harbors (two tests per region). Variance components are reported for over-bark breastheight diameter measured at 21 years (DBH21). Genotype x environment (GE) interactions involving different wild populations of Douglas-fir accounted for little variation in DBH21 across the western Washington regions studied. Interaction involving female parents nested within populations was the most important GE effect; explaining 2% of total variation in DBH21. However, this interaction was of limited practical importance since the superior female parents for DBH21 generally showed good stability across tests. Results from this study support selection of superior coastal Douglasfir genotypes that can produce strong, stable growth across a range of site environments encountered in western Washington.

Mots clés

  • Coastal Douglas-fir
  • genotype x environment
  • genetic stability
  • breast-height diameter.
Accès libre

Growth Rhythm Parameters as Components of Hybrid Vigour in Young Seedlings of Hybrid Larch (Larix decidua x L. kaempferi)

Publié en ligne: 19 Oct 2017
Pages: 42 - 53

Résumé

Abstract

Heterosis for growth traits was investigated on 2-yrold seedlings from related intra- and inter-specific progenies collected in hybridisation seed orchards combining Larix decidua (EL) and L. kaempferi (JL). Following taxa identification, seedlings phenology and growth were observed over a complete growing season in two experiments. Start, cessation, duration and rates of growth for the different taxa were explored in relation to hybrid vigour. Variable levels of heterosis were observed, depending on the genetic background of the parental species, the species over which superiority was evaluated, environmental conditions and the traits considered. While significant and consistent differences have been observed between hybrids and their related EL progenies for phenological growth traits, a better timing of the growth rhythm over the growing season together with a greater growth efficiency allowed for a consistently positive heterosis over EL. The situation appeared more complex with JL as heterosis could be either positive or negative. Besides the high variation in heterosis levels, the way heterosis for height built up over the growing season seemed also to be variable according to genetic backgrounds: cumulative constant superiority of the hybrid for growth rhythms along the growing season or greater growth rates during discrete periods of time.

Mots clés

  • heterosis
  • phenology
  • growth
  • hybrid larch
  • Larix.
Accès libre

Estimation of Clonal Variation in Seed Cone Production Over Time in a Scots pine (Pinus sylvestris L.) Seed Orchard

Publié en ligne: 19 Oct 2017
Pages: 53 - 62

Résumé

Abstract

Possibilities for early selection of clones for future seed cone production were studied in a clonal seed orchard of Scots pine (Pinus sylvestris L.) in northern Sweden over the first 30 years following establishment. The annual data were modelled as series of bivariate analyses. The correlations between cone production of clones in any individual year and that of a previous year, and cumulative cone production over all years were studied. The corresponding multivariate analysis for a full data fit simultaneously was best estimated with a genetic distance-based power model (AR). The genetic (variation among clones) and environmental variation were of the same magnitude. The genetic correlations were larger than the phenotypic correlations and both increased with orchard age. Basing selection of clones on a single observation at an early age to improve future cone production was not effective, but efficiency increased if cumulative cone count over many years was used. Year-to-year genetic correlations indicated that early forecasts by clone of cone production at mature ages are highly uncertain. Reliable predictions (moderate correlations) could be achieved only if based on rather mature grafts, 14 or more years after establishment.

Mots clés

  • Pinus sylvestris
  • fruitfulness
  • longitudinal data
  • reproductive competence
  • broad-sense heritability.
Accès libre

Responses of Falcataria moluccana seedlings of Different Seed Sources to Inoculation With Uromycladium tepperianum

Publié en ligne: 19 Oct 2017
Pages: 62 - 68

Résumé

Abstract

Falcataria moluccana (batai) is one of the valuable multipurpose tree species for forest plantations, particularly in Malaysia and Indonesia. Gall rust disease caused by Uromycladium tepperianum (Sacc.) is one of the most destructive diseases in Batai plantations. The disease causes severe damage at all developmental stages of the plant from the nursery stage to mature trees in the field and includes the development of chocolate brown, cauliflower-like or whip-like galls on the stem, branch, petiole, shoot and pod. Different seed sources may respond differently to gall rust fungus. Thus, the responses of F. moluccana seedlings from 6 selected seed sources to gall rust disease caused by U. tepperianum, were evaluated, at the Brumas Estate, Malaysia, in terms of gall rust disease severity, mortality, and disease infection rate of the seedlings. Based on disease severity, infection rate and cumulative mortality due to gall rust disease, the wamena was found to be the best seed source in relation to gall rust disease resistance.

Mots clés

  • Falcataria moluccana
  • seed sources
  • Uromycladium tepperianum
  • artificial inoculation
  • resistance.
Accès libre

Characterization of Juglans nigra (L.), Juglans regia (L.) and Juglans x intermedia (Carr.) by SSR markers: a case study in Italy

Publié en ligne: 19 Oct 2017
Pages: 68 - 78

Résumé

Abstract

Juglans nigra and Juglans regia are economically important species in Europe, Asia and North America. Natural hybrids between the two species, known as Juglans x intermedia (Carr), are valued for timber production. We tested ten nuclear microsatellite markers to (1) identify new J. x intermedia hybrids and characterize their parentage species J. regia and J. nigra (2) detect J. nigra genotypes with a spontaneous crossing ability with J. regia in a mixed Italian population. This study was also designed to confirm the transferability of ten black walnut SSR loci to Persian walnut All ten microsatellites amplified in both species, producing fragments of variable size; eight (7.14%) were common, 68 (60.7%) amplified in J. nigra and 36 (32.1%) in J. regia only (private alleles). Indices of genetic diversity revealed high level of variability. The Principal Coordinate Analysis on the basis of total 112 alleles divided the total sample set into three main groups: J. nigra, J. regia and J. x intermedia hybrids. Performing the microsatellite fingerprinting, a triploid hybrid plant with two genome parts of J. nigra and one part of J. regia was identified. The cytological analysis proved this triploid state showing 48 somatic chromosomes. The mother testing analysis of the 7 diploid hybrids by exclusion method indicated one putative hybridogenic mother plants. The sequence analysis of amplified fragments confirmed the cross-species amplification of SSR. Inter-specific differences between alleles were due not only to simple changes in the number of repeats but also to mutations in the flanking regions.

Mots clés

  • Juglans
  • interspecific hybrids
  • microsatellites
  • cross-species amplification
  • sequencing.
Accès libre

Genetic Variation and Structure of native and introduced Casuarina equisetifolia (L. Johnson) Provenances

Publié en ligne: 19 Oct 2017
Pages: 79 - 85

Résumé

Abstract

Casuarina equisetifolia is an important tree species in tropical/subtropical zones of Asia, the Pacific and Africa. In this study, 220 individuals from seven native provenances and eleven introduced provenances of C. equisetifolia were analyzed to assess the genetic variation and structure using amplified fragment length polymorphism (AFLP) markers. A total of 465 bands were obtained by eight primer pairs, among which 153 were polymorphic. The mean NEI’s gene diversity H = 0.2113 calculated for 18 provenances and the total gene diversity HT = 0.4065 calculated for native provenances suggested abundant variation within provenances and species. High genetic divergence coefficient (GST = 0.4737) and low gene flow (Nm = 0.5555) detected among native provenances suggesting high differentiation of C. equisetifolia. An AMOVA analysis for native provenances revealed a high proportion (46.07%) of the total genetic variation distributed among provenances. The UPGMA clustering (r = 0.8028) and the Mantel test (r = 0.0716) for native provenances showed there was no correlation among genetic relationships and geographical distribution. The genetic information provided important implications for the future conservation and breeding programs of C. equisetifolia.

Mots clés

  • Casuarina equisetifolia
  • AFLP markers
  • genetic variation
  • genetic structure
  • native range
  • introduced range.
Accès libre

Annual Fertility Variation in Clonal Seed Orchards of Teak (Tectona grandis L.f.) and its Impact on Seed Crop

Publié en ligne: 19 Oct 2017
Pages: 85 - 93

Résumé

Abstract

Fertility variation was studied in two clonal seed orchards (CSO) of teak in four consecutive years (2003-2006). Both orchards were raised in 1976 with grafts of phenotypes selected for growth and form. The seed orchards of CSO I (Topslip, Tamil Nadu State) and CSO II (Walayar, Kerala State) have 15 and 20 clones, respectively, with 13 common clones. The proportion of flowering ramets was generally low ranging from 16 to 53% across years. The best fruit yield during the study period was around 18 kg ha-1 in CSO I and 17 kg ha-1 in CSO II. Highly significant clonal variation and clone by year and clone by site interactions were observed for fertility traits. The clonal contribution was more skewed in poor flowering years than in abundant flowering years and in CSO II than in CSO I. Broad sense heritability for flower and fruit production per tree was low to moderate (0.16 to 0.55). Flower and fruit production by individual ramets in successive years were positively correlated. Correlations between reproductive and growth traits were generally low, but correlation was strong between flowering and fruiting. Fertility variation and group coancestry were higher in poor flowering years than in abundant years and in CSO II than CSO I. Restricting seed collection to abundant flowering years, adjusting ramet number to balance contribution of clones and mixing of seeds from successive years are suggested to reduce relatedness among orchard progeny. The usefulness of low input breeding options for teak like seed production areas are also discussed.

Mots clés

  • Flowering
  • fruit production
  • diversity
  • coancestry
  • heritability
  • status number.
Accès libre

Short Note: Internal Size Standard for Microsatellite Genotyping

Publié en ligne: 19 Oct 2017
Pages: 94 - 96

Résumé

Abstract

The in-house production of fluorescently labelled

internal size standard offers the advantage of cost saving

over the commercial size standard in microsatellite

genotyping. Based on the reported in-house internal size

standard protocol, we have improved the method by generating

21 DNA fragments (in a standard named as HM-

400) with each size similar to that of the commercial

size standard. The consistent amplification of the correct

fragment size was optimised via primer modulation

for non-templated nucleotide addition by Taq DNA polymerase.

A total of six microsatellite loci were used to

assess the accuracy of HM-400 and the mean standard

deviation of the size data was 0.19. The differences

between the fragment size means for samples sized

using HM-400 and commercial size standard were small

with an average of 0.29 bp. The production cost of HM-

400 was only 10% of the cost of commercial size standard.

Mots clés

  • size standard
  • microsatellites
  • genotyping
  • population genetics
  • dipterocarps.
Accès libre

Inheritance Pattern of Growth and Wood Traits in Teak (Tectona grandis L.f.).

Publié en ligne: 19 Oct 2017
Pages: 97 - 101

Résumé

Abstract

Inheritance pattern of wood traits, especially heartwood/ sapwood percentage and specific gravity and interactions of wood traits with other growth traits were investigated in a 27-year-old half-sib progeny trial of teak. Wood traits showed highly significant variation for specific gravity, heartwood and sapwood percentage at family level. There was non-significant family vs. replication variation for these traits. Among the growth traits, there was significant variation for height and girth. Families and individual trees showed varying levels of heritability. Among the growth traits, height showed high heritability (individual tree heritability, h2 (i) = 34.3%; family heritability, h2 (f ) = 34.1%) followed by girth (h2 (i) = 19.4%; h2 (f ) = 31.4%). Among the wood traits, maximum heritability values were obtained for sapwood percentage (h2 (i) = 76.6%; h2 (f ) = 70.7%) and heartwood percentage (h2 (i) = 76.9%; h2 (f ) = 69.7%). Specific gravity exhibited heritability values of 29.1 and 41.8%, at individual tree and family level, respectively. Family heritability was higher than single-tree heritability for specific gravity; single-tree heritability exceeded family heritability for heartwood percentage. Specific gravity exhibited significant positive genotypic correlation with heartwood percentage suggesting that improvement in heartwood percentage would lead to a correlated improvement in specific gravity. Heartwood percentage showed significant positive correlation with growth traits viz., height and girth. Some of the families showed good GCA for growth and wood traits investigated. The good general combiners identified in the present study can be used for establishment of advanced generation seed orchards and breeding arboreta for improvement of teak for specific or combination of above traits.

Mots clés

  • Inheritance pattern
  • half-sib progeny trial
  • heritability
  • heartwood percentage
  • sapwood percentage
  • height
  • girth
  • specific gravity
  • general combining ability
  • genetic gain.
Accès libre

Determining the Optimal Age For Selection by Modelling the Age-Related Trends in Genetic Parameters in Eucalyptus Hybrid Populations

Publié en ligne: 19 Oct 2017
Pages: 102 - 112

Résumé

Abstract

Ten factorial mating designs using a combined total of 88 females, 107 males, 684 families and 37,206 individual trees were used to model the age-related trends in genetic parameters and genetic gain between four and 65 months in the Eucalyptus urophylla x grandis breeding population in Republic of Congo. Selection was either of pure species (as parents for continued breeding) or individual hybrids for commercial plantations based on clonal varieties. The variance components were significantly different from zero for female, male and female-by-male interaction effects for volume. The age-related trends in additive, dominance and environmental variances, modelled by nonlinear functions, showed three phases corresponding to different stages of competition and growth. Male and female narrow sense heritabilities were high (h2 Am= 0.70 and h2 Af = 0.90, respectively for highest estimates) compared with individual broad sense heritability (h2 ind= 0.45). They were modelled by polynomial functions that did not display specific trends with age. The age-age correlations, modelled by a response surface, were higher than 0.8 after 36 months. A similar trend with age was observed for additive and total genetic effects. Genetic gain was calculated by combining the different models. The genetic gain was higher for female than for male. Considerable gains can be achieved by clone selection. The efficiency of selection indicated an optimal age of 54 months for juvenile selection of males and females and a mature age for ortets. The trend in efficiency of selection per time unit showed that juvenile selection for volume is much more efficient than adult selection whatever the age.

Mots clés

  • Eucalyptus
  • volume
  • reciprocal recurrent selection
  • variance components
  • heritability
  • age-age correlation
  • optimal age of selection.
Accès libre

Genetic Parameters and Genotype by Environment Interactions for Green and Basic Density and Stiffness of Pinus radiata D. Don Estimated Using Acoustics

Publié en ligne: 19 Oct 2017
Pages: 112 - 122

Résumé

Abstract

Genetic parameters and genotype by environment interactions for wood properties of 13-year-old Pinus radiata were determined by sampling two progeny trials on contrasting sites in the southern slopes of New South Wales, Australia. Heritability of green and basic density were determined together with dynamic modulus of elasticity (MOE) measured using TreeTap. The phenotypic variance in MOE (CV 17-18%) was almost three times that of basic density. MOE and basic density were highly heritable at both sites (h2 0.57 & 0.79 for MOE & 0.59 and 0.85 for density). There was a moderately strong genetic correlation between MOE and basic density (0.64 across-sites). No genotype x environment interaction was detected in MOE or basic density. Basic density and MOE were lower on the warmer, lower rainfall site.

Mots clés

  • Pinus radiata
  • standing tree acoustic tools
  • dynamic modulus of elasticity
  • basic density
Accès libre

Agrobacterium tumefaciens-mediated Transformation of Jatropha curcas: Factors Affecting Transient Transformation Efficiency and Morphology Analysis of Transgenic Calli

Publié en ligne: 19 Oct 2017
Pages: 123 - 128

Résumé

Abstract

An efficient system for Agrobacterium tumefaciensmediated transformation of Jatropha curcas was developed in this study. Several factors affecting the transformation efficiency were optimized, including the explant type, preculture and coculture periods, usage of acetosyringone and density of A. tumefaciens. Compared with other explants, 2-day precultured and cocultured hypocotyl explants showed a significant GUS transient expression efficiency (67.7%). Moreover, adding AS showed a remarkable increase in transformation efficiency. After infecting with A. tumefaciens, hypocotyl explants were subjected to expansion and proliferation on MS medium with 1.0 mg· l-1 IBA and 0.5 mg· l-1 BA. Transformants were demonstrated by the GUS assay and PCR analysis. Rate of hypocotyl explants forming resistant calli reached 67.08%. Furthermore, in the transformed calli development, morphologic changes (calli superficial development and internal structure) were observed by SEM and LM. The present study has provided a fundamental information and research approach for the future study of inducing new traits to J. curcas and genetic modification.

Mots clés

  • Jatropha curcas
  • Agrobacterium tumefaciens-mediated transformation
  • light microscopy
  • scanning electron microscopy.
Accès libre

The Relative Contribution of The Male and Female to The Variation in Reproductive Success in Eucalyptus globulus

Publié en ligne: 19 Oct 2017
Pages: 129 - 138

Résumé

Abstract

Low and variable capsule and seed set is a major factor limiting seed production in Eucalyptus globulus seed orchards. This study identified the relative contribution of the maternal and paternal parent to reproductive success in E. globulus, and examined the genetic basis to the observed variation. Reproductive success was measured in terms of the number of viable seeds obtained per flower crossed. Data on the reproductive success of numerous genotypes from the Furneaux, Strzelecki Ranges and Otways races were obtained from: (i) 12 years of operational full-sib crossing; (ii) a designed fullsib diallel mating scheme; and (iii) capsule retention trials conducted over three seasons at two Tasmanian seed orchards on the same ramets of different genotypes. Analysis of the sparse operational data revealed that both male and female factors significantly affected reproductive success, accounting for 5.0% and 7.9% of the variation respectively. The more precise diallel crossing revealed that a large, and significant, proportion 55%, of the variation in reproductive success between crosses at a single site was explained by the female parent. The male parent explained only 6.7%, but this effect was not statistically significant and was related to variation in in vitro pollen germination. The significant female effect was found to be consistent at the genotype level across seasons, sites and pollination techniques suggesting a genetic basis to the variation. It is argued that selection of genetically fecund females is a key consideration in reducing costs of manual pollination for breeding and deployment purposes.

Mots clés

  • Eucalyptus globulus
  • capsule set
  • seed set
  • capsule abortion
  • reproductive success
  • mating system
  • parental contribution.
Accès libre

The Contribution of Pollen Germination Rates to Uneven Paternity Among Polycrosses of Cryptomeria japonica

Publié en ligne: 19 Oct 2017
Pages: 139 - 144

Résumé

Abstract

Polycrossing is a very useful and cost-effective approach when designing mating trials. However, since the maternal general combining ability (GCA) in polycross designs is estimated on the assumption of equal contributions from paternal parents; any unequal paternal contribution leads to biased GCA estimates. Progeny from polycrossing Cryptomeria japonica, in which three mixtures from three paternal donors were crossed with each of three maternal parents, were analyzed using microsatellite markers to detect departures from equal paternal contribution. The deviations from equal paternal contribution were evaluated using a χ2 goodness of fit test. In this test, we examined the null hypothesis of equal paternal contribution for each mother tree. Two different methods were used to calculate paternal contribution: first, simply the number of seeds produced by each male parent, and second, the number of seeds produced by each male parent weighted according to the proportion of full seeds in single cross. The results of the χ2 test showed that the contribution to seed production by each paternal clone differed significantly in all polycrosses. The average pollen germination rate was significantly different between paternal clones. The contribution of each pollen donor in a polycross was related to their pollen germination rate.

Mots clés

  • Male reproductive success
  • Paternal success
  • GCA
  • Molecular marker
  • Polymixes.
Accès libre

The Impact of Phenological and Artificial Factors on Seed Quality in a Nematode-resistant Pinus densiflora Seed Orchard

Publié en ligne: 19 Oct 2017
Pages: 145 - 152

Résumé

Abstract

To clarify the relationship between the impact of phenological and/or artificial factors on seed quality, we measured the numbers of strobili on nematode-resistant Pinus densiflora clones grown in an immature and relatively small scale (700 m2) seed orchard. In addition, we established the clonal identities of all ramets, identified the paternal parent of the seeds, and assessed the resistance of seedlings to nematode infection. We also clarified the quantitative differences of strobili among clones; one clone produced 86.4% and 70.8% of all male strobili and female strobili, respectively. However, given that the total contamination ratio of the orchard was 82.0%, immigrant pollen had a larger impact on the success of actual crossing than phenology. Seedlings with a resistant maternal parent were resistant, even when their paternal parent was from outside the orchard. Two unselected clones were also planted in the seed orchard, one of which was not resistant and was associated with a maternal contribution of 34.7% of all seed stock. These findings suggest that, despite having a large impact on the crossing, immigrant pollen has a minor impact on seed resistance. Conversely, unselected and nonresistant clones have a marked impact on seed resistance. We concluded that artificial factors have larger impact on the seed quality than phenological factors in this orchard and the seeds will be of sufficient quality for supplying the market once nonresistant clones have been removed from the orchard.

Mots clés

  • nematode resistant
  • Pinus densiflora
  • pollen contamination
  • resistant ability
  • seed orchard
  • seed quality
  • SSR marker.
Accès libre

Genetic Variation in Seed Size and Germination Patterns and their Effect on White Spruce Seedling Characteristics

Publié en ligne: 19 Oct 2017
Pages: 152 - 161

Résumé

Abstract

We determined the degree to which families differ in seed and germination characteristics and examined the extent to which these characteristics influence the early growth of 75 open-pollinated white spruce families. Seed characteristics (1000-seed weight, length, width, area, volume) were measured for 400 seeds per family. Germination variables (germination capacity, peak value, germination value) were determined for each of the 75 families under controlled conditions and germination patterns were modelled using the Weibull function. Seedling characteristics (height, diameter, shoot and root dry weights) were measured at the end of the first and second growing seasons under standard nursery cultural practices. Statistically significant family variation (p < 0.0001) was found for all seed characteristics and germination variables measured. The between-family variance explained 23% to 98% of the total variance of morphological and physiological seed characteristics. Family differences at the seed stage explained up to 33% (root dry weight) and 12% (shoot dry weight) of the family differences observed at the one-year and two-year seedling stages, respectively. Since, in this study based on a comparison of family means, a maximum of only 12% of the family differences observed at the two-year seedling stage were explained by the effect of seed size, a selection for families with better juvenile characteristics could be envisaged without considering the maternal effect of seed size.

Mots clés

  • Weibull function
  • genetic variation
  • repeatability
  • heritabilities
  • maternal effect
  • Picea glauca.
Accès libre

Effects of Cryoprotectants and Post-storage Priming on Seed Germination of Sugi (Cryptomeria japonica

Publié en ligne: 19 Oct 2017
Pages: 162 - 168

Résumé

Abstract

Among the ex situ methods for the preservation of forest tree germplasm, conventional seed banking is considered the most efficient method for the majority of species whilst cryopreservation has an important role in long-term conservation. The influence of cryoprotectants prior to liquid nitrogen (LN) storage and osmoconditioning priming treatments with polyethylene glycol (PEG) after LN storage were evaluated for germination (%), germination value (GV) and mean germination time (MGT) in seeds of Cryptomeria japonica. Sugi seeds were treated with two cryoprotectants (DMSO and PVS2) before immersion into LN and stored for three days. Although the C. japonica seeds survived liquid nitrogen treatment, their viability was reduced from 25% of intact seeds to 17% in LN. The seeds treated with 35% DMSO showed higher germination (28%) as compared with seeds directly-immersed in LN without cryoprotectant treatment. In contrast, PVS2 pretreated seeds decreased germination (13%). Two concentrations of PEG priming treatments were carried out. Osmoconditioning treatment in -0.4 MPa PEG solution after removal from LN enhanced the subsequent germination percentage and decreased MGT. PEG treatments at both -0.4 and -1.2MPa to PVS2 pretreated seeds before cryopreservation partially alleviated the negative effect of PVS2. DMSO pretreated seeds immersed into LN and treated with -0.4MPa PEG maintained the 28% of germination obtained in the control conditions and reduced the mean germination time (MGT). It can therefore be summarized that pretreatment with 35% DMSO was suitable for the cryopreservation of C. japonica seeds whilst the PEG priming treatment circumvented imbibitional damage after LN exposure.

Mots clés

  • Cryptomeria japonica
  • seed storage
  • liquid nitrogen
  • cryoprotectant
  • DMSO
  • PVS2
  • priming
  • cryopreservation
  • ex situ conservation.
Accès libre

Identification and Characterization of Microsatellite Markers Useful for Genetic Analysis of Black Spruce (Picea mariana (Mill.) Populations

Publié en ligne: 19 Oct 2017
Pages: 168 - 172

Résumé

Mots clés

  • Picea mariana
  • black spruce
  • microsatellites
  • upland
  • lowland
  • polymorphism.
Accès libre

Phenotypic Selection of Calycophyllum spruceanum on Farms in the Peruvian Amazon: Evaluating a Low-Intensity Selection Strategy

Publié en ligne: 19 Oct 2017
Pages: 172 - 179

Résumé

Abstract

A low-intensity selection strategy was recommended for timber trees in the Peruvian Amazon to maintain genetic variation on farms and produce modest gains in tree growth. The effectiveness of this strategy was evaluated using Calycophyllum spruceanum. Farmers selected 66 mother trees of different ages on farms in seven locations (~20% of all trees in the locations) in one watershed, based on a visual assessment of growth, form and external disease symptoms. Another 66 mother trees were chosen at random. Tree height, stem diameter, stem bifurcations and mortality of progeny of the selected and random groups of mother trees were evaluated at 15, 26 and 38 months in a provenance/progeny test located on farms in the same watershed. Height was significantly greater (10%) in the selected group at 15 months, but it did not differ significantly between the selected and random groups at 26 and 38 months. There were no significant differences in diameter, bifurcations and mortality between the groups. There was significant variation in height and diameter at all measurement ages due to families, and results suggested that variation in bifurcations and mortality due to families was also significant. Based on approximate 95% confidence

intervals, family variances in height and diameter did not differ significantly between the selected and random groups at any measurement age, but evaluations should continue to confirm these tentative conclusions. Some practical implications for tree improvement programs are discussed.

Mots clés

  • tropical timber tree improvement
  • genetic variation
  • growth
  • form
  • mortality.
Accès libre

Growth, Form and Quambalaria Shoot Blight Tolerance of Spotted Gum in North-eastern New South Wales, Australia

Publié en ligne: 19 Oct 2017
Pages: 180 - 191

Résumé

Abstract

A young provenance/progeny trial of spotted gums, which are major hardwood plantation species in subtropical eastern Australia, was studied for growth, form, and damage from Quambalaria shoot blight. The trial contained a wide range of genotypes, mainly of Corymbia citriodora subsp. variegata, with between one and 21 families per provenance. Genetic parameters were calculated from 23 provenances with four or more families. Provenances superior for growth included four well-represented C. citriodora subsp. variegata provenances, all from south-east Queensland, which also had a high proportion of superior families. Overall, Queensland provenances had significantly higher mean diameter and height than those from New South Wales (NSW), although there were several superior NSW families. Provenances superior for growth also displayed good straightness and relatively fine branching. Relatively low Quambalaria shoot blight damage was recorded for four Queensland provenances and one coastal NSW provenance, which all had high proportions of families with low damage. Provenances that were putative intergrades between C. citriodora subsp. variegata and C. maculata tended to have high damage levels. However, some mediocre provenances contained superior families potentially useful for breeding. Regressions of Quambalaria damage index (QDI) on latitude, and mean height growth on QDI, were highly significant and moderately strong (0.51 and 0.58, respectively), indicating increasing damage in more southern material, and a retarding effect (although not striking) of damage on growth. Individual heritability estimates were low (zero to 0.14) for growth and form, and moderate for QDI (0.31). The genetic correlations for QDI with growth traits were strong and negative (-0.77 and -0.88), supporting a strategy of selecting vigorous trees for breeding programs from provenances and families superior for these traits.

Mots clés

  • Spotted gum
  • Corymbia
  • Quambalaria pitereka
  • Quambalaria shoot blight
  • growth
  • form
  • genetic relationships
  • provenance trial
  • family trial.
Accès libre

Genetic Variation Amongst and Within The Native Provenances of Pinus radiata D. Don in South-eastern Australia. 2.Wood Density and Stiffness to Age 26 Years

Publié en ligne: 19 Oct 2017
Pages: 192 - 204

Résumé

Abstract

Two progeny trials of native provenances of Pinus radiata, representing the 1978 seed collection, were assessed for wood density and standing tree acoustic velocity. One trial, planted in 1980 in southern New South Wales, Australia contains all five provenances. The second trial, planted in the same region in 1982 contains only the island provenances. Results for extracted wood density, assessed from pith to bark in 5 ring segments, and standing tree acoustic velocity, measured at age 24 or 26 years, are reported. Large differences between the mainland and island provenance were apparent for wood density and stiffness. The mainland provenances were very similar for density and followed the “normal” pattern of change with a gradual increase from the pith, followed by a plateauing around age 20. Neither of the island provenances followed this pattern of change in density: Cedros had stable density across the 4 inner most segments and Guadalupe had stable density for the inner two segments followed by a linear increase. Juvenile density was higher in both the island provenances than the mainland provenances. The island provenances differed from each other for standing tree acoustic velocity, with velocity being higher in Guadalupe provenance. Heritabilities for wood density and acoustic velocity (average 0.37) were higher than those for tree growth and form. Across the stem radius, heritability of density was variable with some segments having zero heritabilities in some provenances, particularly Cambria, Cedros and Guadalupe. Heritability for acoustic velocity was highest for Cambria and the island provenances. Within the mainland provenances, little difference was found between populations for either wood density or acoustic velocity. Density and standing tree acoustic velocity were negatively genetically correlated with tree diameter. Differences in provenance means were greater for acoustic velocity than for density in the outermost segment. Provenance rankings also differed, with the rankings for acoustic velocity being similar to those for density in the 2nd segment from the bark. The genetic correlations between density and velocity reached a maximum for 3rd segment. These results indicate that outerwood density is not the sole driver of acoustic velocity, and that the sound wave is perhaps not travelling through the outer most wood, but is penetrating some distance into the tree.

Mots clés

  • Pinus radiata
  • provenances
  • Californian collection
  • heritability
  • wood density
  • acoustic velocity.
Accès libre

Comparative Performance of Corymbia Hybrids and Parental Species in Subtropical Queensland and Implications for Breeding and Deployment

Publié en ligne: 19 Oct 2017
Pages: 205 - 212

Résumé

Abstract

Eighty six full-sib Corymbia F1 hybrid families (crosses between C. torelliana and four spotted gum taxa: C. citriodora subsp. variegata, C. citriodora subsp. citriodora, C. henryi and C. maculata), were planted in six trials across six disparate sites in south-eastern Queensland to evaluate their productivity and determine their potential utility for plantation forestry. In each trial, the best-growing 20% of hybrid families grew significantly faster (P = 0.05) than open-pollinated seedlots of the parent species Corymbia citriodora subsp. variegata, ranging from 107% to 181% and 127% to 287% of the height and diameter respectively. Relative performance of hybrid families growing on more than one site displayed consistency in ranking for growth across sites and analysis showed low genotype-by-environment interaction. Heritability estimates based on female and male parents across two sites at age six years for height and diameter at breast height, were high (0.62 ± 0.28 to 0.64 ± 0.35 and 0.31 ± 0.21 to 0.69 ± 0.37 respectively), and low to moderate (0.03 ± 0.04 to 0.33 ± 0.22) for stem straightness, branch size, incidence of ramicorns, and frost and disease resistance traits at ages one to three years. The proportion of dominance variance for height and diameter had reduced to zero by age six years. Based on these promising results, further breeding and pilot-scale family forestry and clonal forestry deployment is being undertaken. These results have also provided insights regarding the choice of a future hybrid breeding strategy.

Mots clés

  • Spotted gums
  • Hybrid
  • Corymbia
  • Eucalypt
  • Quambalaria
  • Breeding strategy
  • Deployment
  • Heritability
  • Genetic parameters.
Accès libre

Performance and Genetic Parameters of Somatic and Zygotic Progenies of Coastal Douglas-fir at 71/2-Years across Washington and Oregon, USA

Publié en ligne: 19 Oct 2017
Pages: 212 - 219

Résumé

Abstract

Five genetic tests involving 37 somatic clones of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were planted March 2000 in Weyerhaeuser plantations across western Washington and Oregon States, USA. Four of the tests are in Longview, Twin Harbors and Vail regions of Washington, and one test is in Springfield, Oregon. Each test is based on single-tree plots with 12 randomized complete-blocks. The 37 coastal Douglas-fir clones were propagated by somatic embryogenesis from four full-sib families. Zygotic seedlings from two of these full-sib families were planted across all five tests to allow comparison between somatic and zygotic trees of the same pedigree. Results are reported for survival, stem height, diameter at breast-height (DBH), volume and stem sinuosity at 71/2- years. On average the total population of 37 somatic clones had less stem sinuosity, but grew more slowly than zygotic trees across the five tests studied. However, the best 20% of somatic clones for growth produced 25% greater stem volume at 71/2-years than the zygotic fullsib families. Height had a clonal heritability of 0.61 ± 0.09, DBH 0.64 ± 0.06, volume 0.58 ± 0.08 and stem sinuosity 0.26 ± 0.06. The clonal genetic correlation between height and DBH at 71/2-years was 0.98 ± 0.01, while stem sinuosity was adversely genetically correlated with growth. Clonal performance for growth and stem sinuosity was stable across tests with overall between-test correlations of 0.96 to 0.98. This clonal stability resulted in little variance due to clone x test interactions.

Mots clés

  • Coastal Douglas-fir
  • somatic and zygotic trees
  • growth and form
  • clonal heritabilities
  • clonal stability.
Accès libre

Distribution of Microtubular Cytoskeletons and Organelle Nucleoids During Microsporogenesis in a 2n Pollen Producer of Hybrid Populus

Publié en ligne: 19 Oct 2017
Pages: 220 - 226

Résumé

Abstract

The distribution of microtubular cytoskeletons and organelle nucleoids during microsporogenesis in Populus simonii Carr. x P. nigra L. ‘Tongliao’ was studied by indirect immunofluorescence and 4’,6-diamidino-2- phenylindole (DAPI) staining. Our purpose was to reveal the relationship between changes in microtubule and chromosome behavior and cytokinesis and to explain the mechanism of 2n pollen production. We observed stable frequencies of 2n pollen production, ranging from 1.56% to 2.29%, between 2006 and 2008. Moreover, conjoined pollen grains were also observed. Meiotic abnormalities, including univalents, lagging chromosomes and micronuclei, were observed during microsporogenesis. Triads and dyads were also detected in meiotic products. Parallel spindles in metaphase II were unable to fuse, owing to the existence of an organelle band. Regularly, in telophase II, primary phragmoplasts were organized between sister nuclei, and secondary phragmoplasts formed between non-sister nuclei. Cell plates were initiated by centrifugal expansion of phragmoplasts and cytoplasmic infurrowing started at the junctions between the microsporocyte wall and the expanded phragmoplasts. However, a secondary phragmoplast was absent in some microsporocytes. These observations suggest that the occurrence of 2n pollen may result from the partial failure of cytokinesis caused by the absence of secondary phragmoplasts in this hybrid.

Mots clés

  • microsporogenesis
  • microtubular cytoskeleton
  • organelle nucleoids
  • Populus
  • 2n pollen.
Accès libre

A Novel Gel-based Method for Isolation of Stigmas During Controlled Pollination Experiments

Publié en ligne: 19 Oct 2017
Pages: 226 - 233

Résumé

Abstract

In forestry, controlled pollination (CP) allows the combining of genetic material of selected elite trees to produce high quality, and consequently high value, seed. The aim of the present study was to develop a novel isolation method that would allow the technique to be conducted without expensive and time-consuming bagging, making CPs on small-flowered eucalypts commercially viable. We compared the current method of isolating inflorescences using exclusion bags to a novel method which uses sodium alginate gel. Sodium alginate was effective in keeping external pollen away from the stigma, since no seed was produced in those treatments that were not manually pollinated but isolated in this way. In addition, flowers hand-pollinated and isolated with sodium alginate produced progeny that were 100% outcrossed with the applied pollen. The exclusion bags, on the other hand, were not as effective in protecting the stigma as seed was produced in those treatments that were isolated with an exclusion bag without being handpollinated. Sodium alginate isolation also increased the efficiency of control-pollinations as the gel was naturally shed, removing the need for operators to return to the tree to remove the isolation material.

Mots clés

  • control-pollination
  • bud isolation
  • sodium alginate
  • exclusion bag
  • Eucalyptus
  • Artificially Induced Protogyny.
Accès libre

Mitochondrial DNA variation in natural populations of Japanese larch (Larix kaempferi)

Publié en ligne: 19 Oct 2017
Pages: 234 - 241

Résumé

Abstract

Levels of genetic variation within and among natural populations of Japanese larch [Larix kaempferi (Lamb.) Carrière] were evaluated by Restriction Fragment Length Polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) obtained from 209 individuals representing 14 natural populations distributed across most of the species’ natural range in central Japan. Polymorphisms were screened by two RFLP techniques: Southern hybridization of mitochondrial gene probes and Polymerase Chain Reaction (PCR)-RFLP analysis of sequence-tagged sites. However, obvious polymorphism was only detected around the coxIII gene, following digestion with the EcoRI restriction enzyme, in the Southern hybridization analysis. Five haplotypes were identified across the 14 populations, with 11 populations exhibiting little or no genetic variation. Within-population genetic variation was low (HS = 0.158), while population differentiation was substantial (a standardized genetic differentiation measure, G’ST = 0.581). The northernmost, marginal population on Mt. Manokamidake made a significant contribution to the total detected genetic variation. The mtDNA variation displayed geographic structure despite the restricted natural distribution of Japanese larch. Results of this study should be useful for establishing criteria for the genetic conservation and management of natural populations of the species.

Mots clés

  • genetic diversity
  • genetic structure
  • Japanese larch
  • mitochondrial DNA
  • population differentiation
  • RFLP.
Accès libre

Genetic Variation Amongst and Within The Native Provenances of Pinus radiata D. Don in South-eastern Australia. 1. Growth and form to age 26 years

Publié en ligne: 19 Oct 2017
Pages: 242 - 252

Résumé

Abstract

Four hundred and sixty individual families of Pinus radiata, representing all provenances and populations in a 1978 seed collection, plus a local seed orchard control, were planted together in 1980 in a large trial in southern New South Wales, Australia. Provenance means and genetic parameters for growth measured at ages 3, 8 and 26 years plus stem straightness, branch angle and nodality at age 26 years are reported. Large provenance differences were apparent for all traits. The two island provenances, Cedros and Guadalupe, were significantly inferior to the mainland provenances and, due to competition effects, very few trees survived to age 26. Within the mainland provenances, the performance of Año Nuevo and Monterey was almost identical, with Cambria being less vigorous. The best performing seedlot for all traits was the local control. Differences between populations within the mainland provenances were apparent for diameter at age 26 within Año Nuevo and Cambria but not Monterey. Año Nuevo also showed population differences for stem straightness. Heritabilities for early growth were similar within Año Nuevo and Monterey but by age 26, the heritability for diameter was higher in Monterey. Within Cambria, heritabilities for growth and tree form at age 26 were close to zero. Genetic correlations between traits showed similar patterns for each of the mainland provenances, with the exception of correlations with stem straightness within Año Nuevo. Results are discussed in light of recent molecular studies of genetic architecture, levels of inbreeding in the native stands and possible effects of this inbreeding.

Mots clés

  • Pinus radiata
  • provenances
  • Californian collection
  • heritability
Accès libre

The Effects of Drying Temperature and Method of Assessment on the Expression of Genetic Variation in Gross Shrinkage of Eucalyptus globulus Wood Samples

Publié en ligne: 19 Oct 2017
Pages: 252 - 261

Résumé

Abstract

Genetic variation in wood-sample gross shrinkage and basic density was examined in a Eucalyptus globulus base population trial growing in Tasmania, Australia. Gross shrinkage, which includes all components of shrinkage including collapse, was assessed in four ways (calliper- and visually-assessed tangential shrinkage, volumetric shrinkage and radial shrinkage) on samples dried at three temperatures (22°C, 60°C and 105°C). Significant differences between subraces were observed using all measures of gross shrinkage for two or more of the three drying treatments. Furthermore, significant additive genetic variation within subraces was observed in calliper- and visually-assessed gross shrinkage under two or more of the drying treatments, with narrowsense heritabilities greater than or equal to 0.35. There was no obvious trend in heritabilities or coefficients of additive genetic variation with drying temperature. Under the 105°C drying treatment, subrace correlations among calliper-, visually- and volume-assessed gross shrinkage were positive and very strong (≥ 0.97), while these measures were less strongly correlated with radial gross shrinkage at the subrace level (≤ 0.77). Withinsubrace genetic correlations among the first three measures were also strongly positive (≥ 0.95). These high genetic correlations suggest that different drying regimes and the calliper, visual and volume methods of assessment could be used interchangeably to select for reduced tangential gross shrinkage. Estimated subrace and genetic correlations between basic density and measures of gross shrinkage were universally negative (i.e. favourable), although not all were significantly different to zero.

Mots clés

  • Heritability
  • genetic correlation
  • genotype-by-drying- regime interaction
  • drying defect
  • shrinkage
  • collapse
  • basic density.
Accès libre

Evaluation of Pollen Contamination in an Advanced Scots Pine Seed Orchard

Publié en ligne: 19 Oct 2017
Pages: 262 - 269

Résumé

Abstract

The pollination pattern in a Scots pine (Pinus sylvestris L.) seed orchard consisting of 28 clones was studied using nine microsatellite (SSR) loci. The nine SSR loci produced unique multilocus genotypes for each of the orchard’s 28 clones and allowed paternal assignment of the studied 305 seed using paternity exclusion probability of 99.9%. Fifty two percent of the studied seeds were sired by outside the orchard pollen sources (i.e., pollen contamination) and as expected, low selfing (2.3%) was detected. These results are valuable for the evaluation of the seed orchard function and the impact of contamination on the expected genetic gain.

Mots clés

  • Paternity analysis
  • Pinus sylvestris
  • pollination
  • SSR marker.
Accès libre

Population Genetic Structure of Laurus nobilis L. Inferred From Transferred Nuclear Microsatellites

Publié en ligne: 19 Oct 2017
Pages: 270 - 276

Résumé

Abstract

Species with fragmented populations and low population size often display low within-population genetic diversity and strong among-population differentiation. Laurus nobilis L. (Lauraceae), common laurel, has a scattered distribution throughout the Mediterranean, with only few autochthonous populations. Our goal was to elucidate if this species has range-wide genetic structure and if planted material can be traced back to its origin. Genetic diversity was investigated using 4 polymorphic nuclear microsatellites (nSSR) transferred from two species of Lauraceae. Sixty-six laurel trees were selected from 7 widely separated populations within the Mediterranean distribution area of the species. A total of 34 alleles (9 alleles per locus on average) were found. Mean genetic diversity within-population (Hs), was 0.558. Genetic differentiation among populations (GST = 0.243) was high compared to that of other angiosperms. Laurus nobilis can be separated into two main gene pools, one from western (Tunisia, Algeria and France) and the other from eastern Mediterranean (Turkey). The Algerian, Tunisian and French populations presented a strong genetic similarity, compatible with the fact that North African laurel populations could be recently introduced from north-western Mediterranean stock.

Mots clés

  • Laurus nobilis
  • Nuclear microsatellites
  • Genetic diversity
  • Differentiation
  • Mediterranean.
Accès libre

Transfer of Microsatellite Loci For The Tropical Tree Prunus africana (Hook. f.) Kalkman

Publié en ligne: 19 Oct 2017
Pages: 276 - 279

Résumé

Abstract

Using databases of previously published primers, we optimised six nuclear microsatellite markers for Prunus africana for the purposes of studying spatial genetic structure and gene flow. To assess variability, these and three previously transferred loci were screened in populations from Kenya and South Africa. Across both populations most loci were polymorphic, with the exception of a single locus which failed to amplify in the South African samples, exhibiting between 2 and 22 alleles and levels of expected heterozygosity (He) ranged from 0.059 to 0.932. Departures from Hardy-Weinberg equilibrium were detected for all loci but not for all populations. The estimated null allele frequency was very low to moderate and no evidence for linkage disequilibrium was detected.

Mots clés

  • Prunus africana
  • nuclear microsatellites
  • gene flow
  • genetic diversity.
Accès libre

Genetic Diversity of an Australian Santalum album Collection – Implications For Tree Improvement Potential

Publié en ligne: 19 Oct 2017
Pages: 279 - 286

Résumé

Abstract

The Forest Products Commission of Western Australia manages a sandalwood (Santalum spp.) core germplasm collection at Kununurra in the states far north. This collection serves as a significant seed source for sandalwood plantations in the area and remains an important resource for ongoing research. The collection contains S. album trees sourced from Indian arboreta, along with a few trees from West Timor, Indonesia. Also present are representatives of S. macgregorii from Papua New Guinea and S. austrocaledonicum from Vanuatu and/or New Caledonia. Despite the apparently diverse seed origins, the genetic background of many of the accessions remains vague. In this study, diversity and relatedness was assessed by nuclear and chloroplast RFLPs and a phylogeny was inferred. Nuclear RFLPs revealed very low levels of genetic diversity for a tree species, with an observed and expected heterozygosity (Ho and He) of 0.047. Nineteen genotypes were identified within the 233 S. album individuals sampled, with only one tree known to have originated from Timor being differentiated from Indian material. Other trees thought to have come from Timor grouped with those believed to be from India, indicating they were either incorrectly labelled or sourced from heavily modified populations. Despite the poor sample size, chloroplast RFLP analysis revealed no genetic distinction between the Timorese and Indian S. album, which supports the theory of human mediated seed dispersal from Timor to India. The structure of the phylogeny and associated relatedness has assisted in the establishment of seed orchards, designed to ensure maximum diversity is maintained through limiting the proximity of highly related trees. Finally, in light of these and other findings, a hypothesis concerning the evolution of S. album is proposed.

Mots clés

  • Sandalwood
  • Santalum
  • genetic diversity
  • phylogeny
  • evolution.
Accès libre

DNA Methylation in Acacia mangium In vitro and Ex-vitro Buds, in relation to their Within-shoot Position, Age and Leaf Morphology of the Shoots

Publié en ligne: 19 Oct 2017
Pages: 287 - 292

Résumé

Abstract

DNA methylation was analyzed in Acacia mangium Willd. buds collected from in vitro and field growing shoots from the same clone and its juvenile offspring. Shoot tips from in vitro microshoots showed higher levels of DNA methylation for juvenile (23.4%) than for mature (21.8%) plant material, irrespective of their morphology. Likewise, under the same in vitro conditions, the apical buds collected from microshoots exhibiting the juvenile morphology displayed higher DNA methylation rates (23.2%) than those characterized by the mature phyllode morphological type (22.1%), regardless of the age of the plant material source. In outdoor conditions, apical buds collected from mature tree growing shoots were significantly less methylated (20.9%) than the resting axillary buds located just underneath (25.2%) and than the apical buds from the in vitro microshoots of the same clone and mature-like phyllode morphology (22.6%). Overall, the DNA methylation levels found for our Acacia mangium plant materials were consistent with those reported for other Angiosperms, but showed, similarly to other recent findings in different species, that DNA methylation in plants does not always increase with ageing. This was discussed in relation to other phase-related traits and more particularly foliage characteristics, which are conspicuous markers of ageing in this heteroblastic species.

Mots clés

  • Acacia mangium
  • Ageing
  • DNA methylation
  • In vitro
  • Morphological markers
  • Within-shoot position.
Accès libre

Efficiencies of Clonally Replicated and Seedling Testing for Spruce Breeding and Deployment Strategies

Publié en ligne: 19 Oct 2017
Pages: 292 - 300

Résumé

Abstract

Genetic gains based on a genetic test using clonal replicates were compared to those based on a test using seedlings at the same gene diversity and testing effort levels using POPSIM™ Simulator. Three testing and deployment strategies targeting for white spruce (P. glauca [Moench] Voss) and black spruce (P. mariana (Mill.) B.S.P.) in New Brunswick were compared: seedling test with clonal seed orchard deployed as seedlings (CSO_ST), clonally replicated test with clonal seed orchard deployed as seedlings (CSO_CRT), and clonally replicated test deployed as a clone mix (MVF). The breeding populations (BP) were formed by balanced within-family selection and the production populations (PP) were selected by strong restriction on relatedness, i.e., no parent in common. Compared to the seedling test, the clonally replicated test resulted in faster accumulation of additive effects but quicker loss of additive variance in the BP, and this is particular true in the case of lower narrow-sense heritability or less non-additive genetic variance. The quicker loss in BP additive variance was overcompensated for by its faster accumulation in BP additive effect, resulting in higher gain in the clonally replicated test based PPs. Compared to the CSO_ST, the gain superiority of the CSO_CRT increased with generations, decreasing narrow-sense heritability or reducing the amount of non-additive variance. Implementing MVF was the most effective in terms of gain in most simulated cases and its superiority over the CSO_ST increased with generations, decreasing narrowsense heritability, or increasing non-additive genetic variance. Overall results demonstrated significant advantages of using clonally replicated test both for BP advancement and PP selection in most of the scenarios, suggesting that clonally replicated test should be incorporated into current spruce breeding strategies.

Mots clés

  • breeding population
  • production population
  • multivarietal forestry
  • clonal seed orchard
  • genetic gain
  • status number.

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