Volume 28 (2020): Edition 2 (December 2020)

Coccinia abyssinica (Lam.) Cogn. (local name anchote) is a tuber crop that belongs to the family Cucurbitaceae and it is cultivated for food and medicinal uses. It has relatively high quality of nutrient composition compared to other tuber crops, and is considered as the leading proteinous root crop with a high calcium content. Therefore, cooked anchote tubers are highly recommended for patients with broken or fractured bones. Anchote also contains alkaloids, phenols, tannins, flavonoids, and saponins. Although anchote is principally cultivated for its tubers, farmers prefer propagation by seeds as they are easy to store. Farmers select high-quality fruits for future seeds, based on the size of fruits and tubers. Since diseases and pests rarely affect the tubers, protection is not common. However, the fruit fly can damage the fruits, which predisposes them to decay. Although anchote has very high potential as a food security crop, it is neglected and underutilized and has received very limited research attention. Research published so far covers its ethnobotany, nutritional and anti-nutritional composition, traditional methods of reproduction, in vitro reproduction, somatic embryogenesis, anther breeding, and morphological and molecular genetic diversity. This article includes an analysis of previous and current research achievements, presents findings in a comprehensive way, and suggests future direction in crop improvement using biotechnological tools.

The activity of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO; EC 1.4.3.3) in germinating seeds of Callistephus chinensis was studied. For maximum recovery of ACO activity in vitro, the presence of 10% (w/v) insoluble polyvinylpolypyrrolidone (PVPP) and 30% of glycerol in the extraction medium was necessary. The optimum pH for this activity was 7.0. Ethylene production by whole achenes or enzymatic extract increased due to increasing 1-aminocyclopropane-1-carboxylic acid (ACC) concentrations. Saturation level of ACC for in vivo ACO activity was 10⁻¹ M and V_max was 10.89 nL C₂H₄·mg protein⁻¹·h⁻¹. For in vitro ACO activity, the saturation level of ACC was 10⁻³ M and V_max was 2.299 nL C₂H₄·mg protein⁻¹·h⁻¹. Both, in vivo and in vitro ACO activities did not follow Michaelis-Menten kinetics. The Hill coefficients (h) were estimated on the basis of non-linear estimation. Their values were 0.63 for in vivo ACO activity and 1.73 for in vitro ACO activity. The experimental data show that ACO from C. chinensis seeds is an oligomeric enzyme with at least two active sites. During seed germination, in vitro ACO activity was detectable after 12 hours of imbibition, while in vivo ACC conversion to ethylene was observed after 24 h, i.e. – after radicle protrusion. The activity of ACO in C. chinensis seeds is associated with germination sensu stricto, and might be a good marker of this process.

China aster and gaillardia are flowering plants with high economic importance in floriculture. In the present investigation, response of China aster and gaillardia seedlings to inoculation with the arbuscular mycorrhizal fungus Funneliformis mosseae + the plant growth-promoting rhizobacterium Bacillus sonorensis was studied by growing in multipots (pro trays). The germination percentage and plant growth parameters: length of shoots, roots and whole seedlings, stem diameter, biovolume index, plant strength, vigor index, dry weight and nutrient uptake, were analyzed 60 days after sowing. The microbial parameters, mycorrhizal root colonization and spore count, and the population of B. sonorensis in the substrate were also determined. The results brought out that growth of inoculated seedlings was significantly improved as compared to uninoculated seedlings. Based on the plant growth and microbial parameters studied, it was concluded that inoculating the substrate in pro trays with the microbial consortium results in producing vigorously growing seedlings.

The impact of light quality generated by light-emitting diodes (LEDs) on the adventitious root formation and cuttings’ quality of rose hip ‘Konstancin’ under controlled conditions in multilevel growth chamber without access to natural light and in the greenhouse was evaluated. In the growth chamber, the lighting was provided by a combination of red and blue LED arrays and white LED tubes, while in the greenhouse, red and blue LED lights were used as a supplement to natural light. The number of rooted cuttings under both growth conditions was not affected by the light conditions generated by LEDs. However, light quality showed significant effects on the biomass production and development of adventitious roots, with the most stimulating red light generated by LEDs. In the growth chamber, the root biomass of the cuttings illuminated with white LEDs supplemented with red LEDs was on average 2.2 times higher than of the cuttings illuminated with white LEDs only. A similar reaction was noted under greenhouse conditions. Supplementation of natural light with red LEDs resulted in 1.7 times increase of the fresh biomass of roots. Both in the growth chamber and in the greenhouse, illumination with red LEDs promoted axillary bud outgrowth. LED lamps can be used in the production of high-quality rose cuttings, both in greenhouses as a complement to natural light and in multilevel rooms as a sole-source lighting for plants.

Fruit quality attributes are influenced by environmental, agronomic and genetic factors; both cultivars and growing conditions can vary substantially between UK production and imported fruit. This study aimed to record and dissect the most relevant fruit quality traits for berries imported into the UK in the winter months. Blackberry, blueberry, raspberry and strawberry fruit were imported from 11 countries into a Kent-based packhouse (UK) or purchased from major retailers between December 2018 and March 2019. Multiple fruit quality components were assessed for relative contribution towards a high “overall assessment” fruit quality score. It was found that strawberry and blackberry overall scores were affected by sweetness perception, whereas blueberry and raspberry organoleptics are more complex, with overall scores influenced by flavor perception. Multiple raspberry and strawberry fruit quality traits were found to be associated with genotypic differences, indicating a promising potential for genetic improvement through breeding. By contrast, the study findings suggest that there is less potential for genetic improvement in blueberry, and that the environment may have a large effect on blueberry fruit quality traits.

Nucellar embryony is the major obstacle in getting hybrid seedlings in interspecific crosses in citrus. Hence, the present study was conducted to standardize embryo age, culture media for maximizing germination, and subsequent identification of simple sequence repeat (SSR) markers to differentiate the hybrids. A factorial experiment was conducted with three embryo ages – 80–90, 110–120, and 130–140 days after pollination (DAP). The germination of the rescued immature embryos of acid lime × lemon crosses was initiated on three different growing media. The fruits harvested at 130–140 and 80–90 DAP had a higher number of functional seeds (90%). Older embryos (130–140 DAP) and middle-aged embryos (110–120 DAP) germinated in 100% on Murashige and Skoog (MS) medium supplemented with 500 mg·l⁻¹ malt extract, 1.5 mg·l⁻¹ gibberellic acid (GA3), and 0.02 mg·l⁻¹ naphthalene acetic acid (NAA). MS medium supplemented with 500 mg·l⁻¹ malt extract proved better for the germination of embryos taken at 80–90 DAP. Plantlet survival was the highest in younger embryos (80–90 DAP) cultured on MS basal medium (84.21%) and the lowest in older embryos cultured on MS medium supplemented with 500 mg·l⁻¹ malt extract plus 1.5 mg·l⁻¹ GA₃ and 0.02 mg·l⁻¹ NAA. The seedlings obtained from the culture 80–90 DAP had the highest root length (4.9 mm) and shoot length (5.3 mm) at 60 days after inoculation (DAI) on the above medium. SSR marker analysis revealed that CCSM-4 and CAC-33 markers expressed polymorphism between female and male parents, proving their ability to identify the hybrids of ‘Kagzi’ acid lime × ‘Konkan Seedless’ lemon.

Some morphological and physiological traits of seedlings in eight quince populations from seeds obtained in 2015 (350 progenies per population) were evaluated in 2017 and 2018. They resulted from open pollination of ‘Viduja’, KVD2 and KVD4 genotypes as well as from the crossings of ‘Viduja’ × KVD4, KVD2 × ‘Viduja’, KVD2 × KVD4, KVD4 × ‘Viduja’ and KVD4 × KVD2. Populations showed significant differences in some measured traits, including height and diameter of seedlings, canopy width, annual growth, leaf iron, and chlorophyll content, as well as catalase and peroxidase activities. Based on the results of descriptive statistics, a high variation coefficient was observed in canopy width, peroxidase activity, chlorophyll, and iron content traits. Results of simple correlation showed that there were significant positive correlations between leaf iron content and catalase activity as well as canopy width with both annual growth and leaf length. Cluster analysis among populations based on total traits divided the populations into four distinct groups. The role of the female parents was visible in reciprocal crosses of ‘Viduja’ × KVD4 and KVD2 × KVD4, but all populations with similar female parents were not grouped in the same clusters.

Ex vitro rooting and acclimatization of two cultivars ‘Wojtek’ and ‘Zojka’ of blue honeysuckle (Lonicera caerulea var. kamtschatica Sevast.) were studied. To the ex vitro conditions were transferred rooted and unrooted shoots. The post-effect of auxin type and concentration as well as microcutting and soil substrate types were tested. The genetic stability of the plantlets in relation to the mother plants by using amplified fragment length polymorphism (AFLP) and inter simple sequence repeat (ISSR) markers has been also determined. It has been found that in vitro rooted cuttings of both cultivars showed a higher survival rate (max. 88%) and better growth and development when they were rooted on a medium containing a low auxin level (1.0 mg·dm⁻³). The results of the second experiment showed successful ex vitro rooting of blue honeysuckle shoots without auxin treatment. Higher ex vitro rooting and survival rate in the greenhouse have been observed for ‘Wojtek’ (max. 96%) than ‘Zojka’ (max. 88%). Better growth and development of shoots and roots were observed on peat alone or a mixture of peat and perlite as compared to a mixture of peat and sand. The micropropagated plantlets appeared similar to mother plants. Molecular analysis confirmed a high level of genetic stability of blue honeysuckle after 2 years of in vitro propagation. However, among the cultivars studied, ‘Wojtek’ showed slightly higher genetic stability than ‘Zojka’ (99.5% and 97.7%, respectively). For ‘Zojka’ plants, the degree of variation was comparable for AFLP and ISSR markers. For ‘Wojtek’, no polymorphism was detected using the ISSR analysis in contrast to the AFLP analysis.

There has been an increasing interest in soybean cultivation in hydroponic systems. Because soybean plants can utilize nitrogen derived from biological N₂ fixation, the use of Rhizobium inoculated plants may eliminate or decrease the need for mineral nitrogen fertilization in hydroponic systems. Thus, the objective of this study was to establish effective methods for making inoculated soybean transplants for a substrate-based hydroponic system. Inoculated plants were effectively produced by rooting seedling stem cuttings in a medium containing a Rhizobium inoculant. We also investigated the effects of different nitrogen forms and sub-irrigated nutrient solution concentrations on the growth and root nodule formation of the inoculated plants. The application of a nitrogen-free nutrient solution had minimal positive effects on the growth and nodulation of the inoculated plants. Ammonium-fed plants lacked root nodules regardless of the ammonium concentration. Furthermore, a 50% nutrient solution combining with nitrate or urea as the nitrogen source did not promote root nodulation. Therefore, inoculated plants should be subirrigated with an approximately 25% nutrient solution supplemented with nitrate or urea to induce early growth and nodulation prior to transplantation.

At the plants’ exposal to abiotic stress, organic acids, including citric acid, are exuded through their roots. Previous studies have suggested that the exogenous application of citric acid increases antioxidant activity within the plant. Thus, we postulated that organic acids released into the surroundings during times of environmental stress may function as signaling molecules to increase antioxidant enzyme activity. To gain further insight into this phenomenon, we identified individual organic acids exuded from the roots of leafy vegetables under drought stress. We then analyzed enzyme activity and the root/shoot lengths of seedlings after treatment with the types of organic acids found to be exuded from the studied leafy vegetables, including acetic, citric, lactic, and tartaric acids. There was a significant increase in catalase and ascorbate peroxidase enzyme activity in Napa cabbage (Brassica rapa var. pekinensis) after exogenous citric acid application. Root lengths of cabbage (Brassica oleracea var. capitata) and Napa cabbage seedlings were significantly longer in citric and lactic acids pretreated seedlings compared to those of the control. The above results support the conclusion that exogenous application of citric acid alleviates drought stress. However, there is insufficient evidence to prove that organic acids act as signaling molecules to prime neighboring plants for upcoming stress.

Fungal diseases are a persistent problem in the cultivation of white button mushrooms (Agaricus bisporus). The chemical control of pathogens is becoming less effective and less desirable, so new ways to limit these infections are urgently required. What is more, the disease is mostly controlled through cultural practices and good hygiene on mushroom farms. The aim of this study was to evaluate the fungicidal effects of ozone on fungal pathogens of common mushrooms. Experiments with the use of ozone gas for disinfection of growing rooms after the completion of the mushroom growing cycle were carried out. The fungicidal effectiveness of ozone fumigation was evaluated on the basis of the survival rate of the spores of the pathogens tested (Lecanicillium fungicola, Cladobotryum dendroides, Mycogone perniciosa, and Trichoderma aggressivum). Spore suspension was applied to aluminum plates and then was exposed to gaseous ozone. The assessment of the growth of colonies of fungal isolates obtained from infected surfaces was carried out using Rodac contact test plates. The results showed that L. fungicola, M. perniciosa, and C. dendroides isolates were sensitive to the gas ozone. In order to achieve 100% efficacy against Mycogone strains, a minimum of 6 hours of ozonation had to be applied, whereas for Cladobotryum strains, a minimum of 8 hours had to be applied. The Lecanicillium species was the most sensitive to ozonation because 30 minutes of ozonation was enough to gain 100% inhibition of its growth. No satisfactory results were obtained in the case of the pathogenic species of Trichoderma, regardless of the experimental conditions. Nevertheless, this study has demonstrated the usefulness of ozone as a disinfectant for empty growing rooms after the completion of the mushrooms’ cultivation cycle.