Radiata Genotypes Research Articles

Host genotype and microbiome associations in co-occurring clonal and non-clonal kelp, Ecklonia radiata.

A fundamental question in holobiont biology is the extent to which microbiomes are determined by host characteristics regulated by their genotype. Studies on the interactions of host genotype and microbiomes are emerging but disentangling the role that host genotype has in shaping microbiomes remains challenging in natural settings. Host genotypes tend to be segregated in space and affected by different environments. Here we overcome this challenge by studying an unusual situation where host asexual (5 clonal lineages) and sexual genotypes (15 non-clonal lineages) of the same species co-occur under the same environment. This allowed us to partition the influence of morphological traits and genotype in shaping host-associated bacterial communities. Lamina-associated bacteria of co-occurring kelp sexual non-clonal (Ecklonia radiata) and asexual clonal (E. brevipes) morphs were compared to test whether host genotype influences microbiomes beyond morphology. Similarity of bacterial composition and predicted functions were evaluated among individuals within a single clonal genotype or among non-clonal genotypes of each morph. Higher similarity in bacterial composition and inferred functions were found among identical clones of E. brevipes compared to other clonal genotypes or unique non-clonal E. radiata genotypes. Additionally, bacterial diversity and composition differed significantly between the two morphs and were related with one morphological trait in E. brevipes (haptera). Thus, factors regulated by the host genotype (e.g. secondary metabolite production) likely drive differences in microbial communities between morphs. The strong association of genotype and microbiome found here highlights the importance of genetic relatedness of hosts in determining variability in their bacterial symbionts.

Mitigation of lead toxicity in Vigna radiata genotypes by silver nanoparticles

Heavy metal (HM) contamination of the soil through anthropogenic activities influences the living systems and drastically impacts food chain. This study examined the application of silver nanoparticles (AgNPs) in two genotypes (G1 and G2) of Mung bean (Vigna radiata) for ameliorating the Pb toxicity. Different doses of Pb (0, 25, 50 μM) were differentially tackled by AgNPs with the aim of ameliorating the plant attributes. Both genotypes displayed statistically significant quantitative and qualitative modulations for Pb tolerance. In G2, the most prominent increase in plant height (43.79%), fresh biomass (49.56%) and total chlorophyll (20%) was observed at L2 (AgNPs 10 mg/L) in comparison with the control. Overall, photosynthetic rate was increased by 26% in G2 at L6 (AgNPs 25 mg/L + Pb 25 μM). In addition, the results presented 78.5% increase in water use efficiency of G2 while G1 experienced a maximum internal CO2 concentration (209.8%) at L8 (Pb 50 μM). AgNPs triggered balanced uptake of minerals and improved growth of Vigna genotypes. 50 μM Pb was most hazardous and caused maximum reduction in growth of Vigna plants along with a significant suppression in photosynthetic activity, increase in MDA (199.7%) in G1 and H2O2 (292.8%) in G2. In comparison to control, maximum superoxide dismutase (376%), peroxidase (659.8%) and catalase (9.3%) activity was observed in G2 at L11. The application of AgNPs substantially enhanced plant growth and helped them in surviving well in absence as well as presence of Pb. G2 genotype exhibited substantial tolerance capability and revealed less impairment in the studied attributes than G1 and treatment of AgNPs i.e. 25 mg/L was the best level that yielded best results in both genotypes. The results demonstrate that AgNPs mediate response(s) of plants under Pb stress and particularly contributed to HM tolerance of plants and thus showing great promise for use in phytoremediation.

Assessing Genetic Variation in Resistance to Pinewood Nematode (Bursaphelenchus xylophilus) in Pinus radiata D. Don Half-Sib Families

Full understanding and control of pine wilt disease (PWD) is a work in progress and breeding for disease resistance constitutes an essential management strategy for reducing its impact, as evidenced by advanced breeding programs in countries such as Japan. Since Pinus radiata is one of the most commercially relevant species in northern Spain, we designed a study to assess genetic variation in susceptibility to this pathogen using 44 P. radiata half-sib families from the Galician breeding program. Three Bursaphelenchus xylophilus (pinewood nematode, PWN) inoculation experiments were performed to evaluate disease-related variables, estimate genetic parameters, and study sources of genotype by environment interaction (G × E). We also looked at differences in the constitutive chemical compounds of susceptible and non-susceptible individuals. The results showed great variation in PWN susceptibility, with survival rates for P. radiata families ranging from 0% to 90%. In addition, heritability estimates (hi2 = 0.43, hf2 = 0.72) and genetic gain (>26% selecting 50% of the families) were both moderately high for survival. Significant differences in several constitutive chemical compounds were found between susceptible and non-susceptible seedlings in the two susceptibility groups considered. These results confirm the potential of breeding to obtain P. radiata genotypes that are resistant to pine wilt disease and open possibilities for mitigating its future impact on P. radiata stands.

Cross-species Amplification and Molecular Diversity Analysis in Greengram [Vigna radiata (L.) Wilczek] and Ricebean [Vigna umbellata Thunb.

Background: Greengram is the fourth dominant pulse crop grown in India and is highly susceptible to bruchids and yellow mosaic virus. Ricebean belonging to the tertiary genepool of greengram shows resistance to this pest and disease. Ricebean being a minor pulse crop has limited SSR markers. Hence, the present study was conducted to test the cross-species amplification of SSR markers derived from related species which could be helpful in studying the molecular diversity available in each crop and for molecular confirmation of the inter- and intra-specific hybrid developed from the crosses.Methods: Molecular diversity analysis was carried out using 30 genotypes belonging to two species of Vigna (V. radiata and V. umbellata) based on 20 SSR primers derived from adzukibean, commonbean and greengram. Result: Cross species amplification was observed for all the SSR primers pairs used. The number of alleles detected varied from one (VJ 31122A) to four (CEDAAG 001 and MB 91) with an average of 2.55 alleles per primer. Allele size varied from 100 to 292 bp. The PIC value ranged from zero to 0.611 with an average value of 0.377. Dendrograms constructed based on UPGMA and Neighbour-Joining tree method, grouped the genotypes into five clusters and five groups, respectively. The V. umbellata genotypes were grouped in separate cluster from the V. radiata genotypes in both the methods. The obtained DNA polymorphism at intra- and inter-specific level will facilitate the application of molecular breeding approaches for greengram improvement.

Field-scale variability in site conditions explain phenotypic plasticity in response to nitrogen source in Pinus radiata D. Don

AimsProductivity of forest ecosystems is constrained by site resource availability and utilisation at an individual tree level. A better understanding of nitrogen (N) nutrition addition to forest ecosystems is critical for maintaining optimal plantation productivity, given the influence of an environment gradient, genetics, and their interactions.MethodsWe studied the aboveground growth response in a plantation setting of ten commercial P. radiata genotypes to N-fertilisation using three different N sources, and also assessed the effect of on-site environmental factors on this response. We compared, on equimolar basis, the effect of N-fertilisation with inorganic N (NH4NO3), organic N (L-arginine), and the two N sources combined (L-arginine:NO3−) to that of unfertilised trees on tree height, diameter, descriptors of microsite variability, and climate and seasonal information. After 2.5 years of fertilisation, genotype-specific variation in aboveground growth response to N sources were measured, and these were significantly influenced by field-scale heterogeneity.ResultsAcross P. radiata genotypes, trees treated with inorganic N forms showed suppressed growth compared to unfertilised trees, while trees fertilised with organic N (either alone or in combination with inorganic N) were not significantly different than the untreated controls. We provide evidence of significant interactions between N source and genotype, N source and cover as well as genotype and microsite variability affecting temporal trends in tree volume.ConclusionsWe conclude that the comprehension of field-scale variability in soil properties and associated environmental variables is essential for understanding genotype performance as they are crucial determinants of intraspecific variation in response to N-fertilisation.

Generation of interspecific hybrids for introgression of mungbean yellow mosaic virus resistance in Vigna radiata (L.) Wilczek

Vigna radiata genotypes viz., SML 668 and SML 832 and V. mungo genotypes viz., Mash 114 and Mash 218 were crossed in all possible combinations during summer 2015 to generate F1 hybrids. Interspecific hybridization was attempted by using V. radiata genotypes as female parent. Pod set percentage varied from 5.5 percent (SML 832 x Mash 218) to 24.1 percent (SML 832 x Mash 114). The germination percentage ranged from 14.29 to 30.56. Maximum pollen fertility was observed in cross SML 668 x Mash 114 (28.36 percent) followed by SML 668 x Mash 218 (27.03 percent), SML 832 x Mash 218 (24.32 percent) and minimum in SML 832 x Mash 114 (22.59 percent).The purity of hybrids were tested through microsatellite markers. For parental polymorphism, microsatellite markers were selected from related Vigna species such as Vigna unguiculata, Vigna radiata and Vigna mungo. Out of 84 markers used, 46 were polymorphic i.e 54.76 per cent polymorphism between parents. These polymorphic markers were used for confirmation of hybrids produced from different crosses. All the F1 plants gave resistant reaction to Mungbean yellow mosaic virus (MYMV) indicating the introgression of resistance gene(s) from V. mungo to V. radiata.

Chemical control of two Phytophthora species infecting the canopy of Monterey pine (Pinus radiata)

SummaryTwelve active ingredients were screened for their ability to control foliage disease caused by Phytophthora kernoviae and Phytophthora pluvialis. Inhibition of mycelial growth and sporangial production of both pathogens were assessed in in vitro assays after exposure to three concentrations of each active ingredient. While most of these active ingredients inhibited mycelial growth in vitro, due to their widespread use, phosphite, copper oxychloride and metalaxyl‐M were selected for further study. Four rates of each active ingredient were applied to two Pinus radiata genotypes, and detached needle assays at 6 and 90 days post‐treatment were used to determine treatment efficacy and persistence. Untreated needles showed significantly larger lesions than all fungicide‐treated needles after exposure to P. pluvialis or P. kernoviae on both sampling dates. Efficacy and persistence of the three active ingredients did not increase with increase in concentration. Larger lesions were formed on more susceptible genotype after inoculation with both Phytophthora species, even when higher rates of active ingredients were applied. Phosphite, copper oxychloride and metalaxyl‐M have potential to protect commercially planted P. radiata from these two Phytophthora species.

Sequence related amplified polymorphism (SRAP) analysis for genetic diversity and micronutrient content among gene pools in mungbean [Vigna radiata (L.) Wilczek

Vigna radiata (L.) Wilczek, commonly called mungbean is an important pulse crop. Commercial cultivars contain low levels of iron and zinc and it is important to assess genetic variability in the available germplasm for improving micronutrient content in commercial cultivars. The present study was undertaken to study molecular diversity using Sequence-related amplified polymorphism (SRAP) among 21 Vigna radiata genotypes. Twenty nine SRAP primer combinations produced a total of 121 amplified bands which were polymorphic with an average of 4.65 bands per primer. The size of amplified bands ranged from 70bp to 3,000bp and 6 out of 29 SRAP primers were most useful in fingerprinting Vigna radiata genotypes under study. The similarity coefficients between different genotypes ranged from 0.45 to 0.96 with an average similarity value of 0.71. At an arbitrary cut-off at 60% similarity level on a dendrogram, the Vigna radiata accessions were categorized into two major clusters. ML1108 and 2KM115 were found to be genetically similar. SMH99-1A and ML776 showed high iron and zinc content while Satya was poor in iron as well as zinc content. Mapping population involving ML776 and Satya could be used for tagging gene(s) for micronutrient content. The results indicated that SRAP markers were efficient for identification of Vigna radiata genotypes and assessment of the genetic relationships among them.

Lack of genetic variation in tree ring 13C suggests a uniform, stomatally-driven response to drought stress across Pinus radiata genotypes

We assessed the variation in delta(13)C signatures of Pinus radiata D. Don stemwood taken from three genetic trials in southern Australia. We sought to determine the potential of using delta(13)C signatures as selection criteria for drought tolerance. Increment cores were taken from P. radiata and were used to determine the basal area increment and the delta(13)C signature of extracted cellulose. Both growth increment and cellulose delta(13)C were affected by water availability. Growth increment and delta(13)C were negatively correlated suggesting that growth was water-limited. While there was significant genetic variation in growth, there was no significant genetic variation in cellulose delta(13)C of tree rings. This suggests that different genotypes of P. radiata display significant differences in growth and yet respond similarly to drought stress. The delta(13)C response to drought stress was more due to changes in stomatal conductance than to the variation in photosynthetic capacity, and this may explain the lack of genetic variation in delta(13)C. The lack of genetic variation in cellulose delta(13)C of tree rings precludes its use as a selection criterion for drought tolerance among P. radiata genotypes.

Genetic relationship in Vigna mungo (L.) Hepper and V. radiata (L.) R. Wilczek based on morphological traits and SDS-PAGE

Thirty seven diverse genotypes of Vigna mungo and three of V. radiataresembling to V. mungo for seed characters were studied to determine the extent of genetic variation based on morphological characters. In addition, 4black seeded genotypes in each species and8 green seeded V. radiata genotypes were included for SDS-PAGE analysis. Seed proteins were analyzed through slab type SDS-PAGE. High variance was observed for plant height, days to flowering, days to maturity, number of branches/plant, number of pods/plant, pod length, seeds per pod,biomass yield/plant, grain yield/plant and harvest index (%) during 2 consecutive years. First four components of PCA with eigenvalues >1 contributed 78.7 and79.1% of the total variance amongst 40genotypes during 1998 and 1999. The populations with high PC1 values were expected to be high yielding characterised by earlyness, high seed weight and harvest index, all traits strictly related to reproductive phase. Four clusters of genotypes were observed during both the years and genetic diversity was in association for both the years. Based on SDS-PAGE, specific bands were suggested to be used for identifying Vigna radiatafrom mixed germplasm with Vigna mungo. The SDS-PAGE proved to be a powerful tool for differentiating Vigna radiata and Vigna mungo, whereas a low level inter-specific genetic diversity was observed and no clear differentiation was observed both for agronomic characteristics and for geographical origin.

Influence of phosphorus deficiency on the growth response of four families of Pinus radiata seedlings to CO 2-enriched atmospheres

Four half-sib families of Pinus radiata (D. Don) (20080, 20010, 20022 and 20062) were grown in pots under conditions where P was either deficient or adequate and water was supplied daily. Seedlings of all four families were exposed to 340 (ambient levels) or 660 μl CO 2l −1 in controlled-environment chambers for 16 weeks. Families 20010 and 20062 were grown at the same CO 2 concentrations for 22 weeks. A subset of plants grown in the chambers were subject to drought and their water potentials and relative water contents measured. In the glasshouse experiment, photosynthesis, conductance and elongation of needles were measured. The fresh and dry-weights of the tops of the plants were measured in both experiments. Elevated CO 2 concentrations increased shoot growth in all families, apparently through increases in photosynthesis. At 340 μl CO 2l −1, family 20062 accumulated the most dry-weight and 20010 the least. However, family 20010 responded so strongly to 660 μl CO 2l −1 that it produced as much dry-matter as 20062. Phosphorus deficiency generally diminished the response to high CO 2. Again, 20010 was outstanding in that its CO 2 response was least reduced by P deficiency. Carbon-dioxide enrichment did not increase the drought-tolerance of any of the four families, either by reducing conductance or by facilitating osmotic adjustment. These results provide strong indications that the higher levels of atmospheric CO 2 expected in the next century will increase the growth of P. radiata where P availability is adequate, but may reduce growth in areas where rainfall is low. Finally, the capacity to respond to CO 2 enrichment appears to be widely distributed among superior P. radiata genotypes selected by the Forestry Commission of New South Wales. However the magnitude of response varies considerably, particularly where P is deficient.