Relationships and variability of agronomic and physiological characters in mungbean

This study was conducted to determine the variability, heritability and correlations among agronomic and physiological characters of mungbean (Vigna radiata (L.) Wilczek) and to identify their direct and indirect effects on seed yield. Fifty six mungbean accessions were evaluated at Suranaree University of Technology Farm, Nakhon Ratchasima, Thailand using a randomized complete block design with 4 replications. Fourteen characters were collected and analyzed for genotypic coefficient of variation, phenotypic coefficient of variation, environmental coefficient of variation, heritability estimates in broad sense, phenotypic and genotypic correlation coefficients and path coefficients. It was found that genotypes differed significantly for all characters studied. The highest heritability values were recorded on days to flowering and pod length. Seed yield was significantly and positively correlated with pods per plant, clusters per plant, total dry matter (TDM), seeds per pod, seeds per plant, biomass, leaf area index and branches per plant, and negatively correlated with days to maturity. Clusters per plant showed the highest positive direct effect on seed yield followed by 100 seed weight, seeds per pod, TDM and pods per plant. However, the effect of 100 seed weight was substantially minimized by the negative indirect effects of clusters per plant, pods per plant and seeds per pod. These results demonstrate that clusters per plant, seeds per pod, TDM and pods per plant should be used as selection criteria for yield improvement in mungbean.Key words: Agronomic characters, correlation analysis, mungbean, path coefficient analysis, physiological characters, variability, Vigna radiata, yield components

Evaluation of Grapevines for Resistance to Downy Mildew (Plasmopara viticola) under Laboratory and Field Conditions

Downy mildew of grapevine (Vitis vinifera L.), caused by the oomycete Plasmopara viticola, can seriouslydevastate grapevine production in tropical countries, such as Thailand. Four susceptible grapevinecultivars, four potentially resistant lines and 18 F1 hybrids, propagated by air layering and chip budding,were evaluated for resistance to downy mildew at laboratory (using a detached leaf assay) and field (naturalinfection in 2011 and 2013) levels. Significant differences in the disease scores among grapevine genotypes,ranging from 0.54 (resistant) to 4.83 (susceptible) and 3.30 (resistant) to 7.70 (susceptible), were observedunder the laboratory and field conditions respectively. No significant difference in disease severity wasobserved between the two propagation methods or between the two different years of field evaluations.Resistance evaluations under both conditions consistently classified ‘NY88.0517.01’ and ‘NY65.0550.04’ asresistant lines what would be useful as parents for future breeding programmes. Moreover, one F1 hybrid,‘SUT0403.09’, was reported to have considerable resistance to downy mildew under both laboratoryand field conditions for the first time. The field resistance level of this hybrid was almost comparable toits highly resistant parent ‘Wilcox 321’, suggesting its potential for the future development of resistantcultivars in Thailand. Although the ranking of genotypes varied between screening methods, the resistancelevels of the 26 grapevine genotypes evaluated under laboratory and field conditions were comparablebased on the Spearman’s rank correlation coefficients of 0.73 (p ≤ 0.01). These results suggest that thelaboratory screening assay is efficient for the rapid, reliable and economical identification of resistanthybrids in grapevine breeding programmes

Optimization of factors for efficient isolation of protoplasts in sunflower (Helianthus annuus L.)

Abstract Various factors influencing the efficiency of sunflower protoplast isolation including genotypes (10A and PI 441983), tissue types (young leaves and hypocotyls), isolation methods (M1-M5) and cellulase concentrations (0.1, 0.5, 1.0 and 1.5%) were evaluated to obtain optimum protoplast isolation procedures. Young leaves were preferable to hypocotyls in production of viable protoplasts. Genotypes and isolation methods significantly affected both yields and viability of protoplasts from both tissues. Moreover, protoplast yield from leaf tissues was also influenced by cellulase concentrations. Using hypocotyls as explants, 10A line gave the highest number of viable protoplasts (4.24 × 10 6 protoplasts/ g fresh weight [FW]) when incubated at 25°C for 16 h in the optimal isolation solution containing 1% cellulase and 0.5% macerozyme. Higher number of viable protoplasts observed in this genotype, compared to PI 441983, may result from differences in hypocotyl morphology between the two genotypes. By contrast, for leaf explants the highest numbers of viable protoplasts, 6.13 × 10 6 protoplasts/ g FW for 10A line and 8.81 × 10 6 protoplasts/ g FW for PI 441983 line, were achieved when incubated with 0.1 and 0.5% cellulase, respectively, in the optimal isolation solution containing 0.05% driselase, 0.02% macerozyme and 0.1% bovine serum albumin (BSA) at 25°C for 16 h. These results suggest that suitable sunflower protoplast isolation procedures varied according to genotypes and tissue types, and need to be individually optimized

Variety identification and genetic relationships of mungbean and blackgram in Thailand based on morphological characters and ISSR analysis

Genetic diversity and relatedness were measured in 17 mungbean (Vigna radiata (L.) Wilczek) and 5 blackgram (Vigna mungo (L.) Hepper) genotypes by means of inter-simple sequence repeat (ISSR) analysis and morphological characters. Unweighted pair-group method arithmetic average (UPGMA) analysis of 19 morpho-agronomic characters showed clear separation of the genotypes into 3 major groups; cluster I containing 15 Thai cultivated mungbean varieties and breeding lines, cluster IIIcontaining 4 Thai cultivated blackgram varieties, and cluster II containing a mungbean wild relative (subspecies sublobata), a blackgram wild relative (subspecies silvestris) together with an Indian mungbean landrace. Pair wise coefficients of genetic similarity between all genotypes ranged from 0.17 to 0.84 with an average of 0.52. In total, 341 ISSR fragments were amplified for the two Vigna species by ISSR analysis using 18 ISSR primers. The polymorphism revealed with the ISSR primers was 90.6%. The number of amplified fragments varied from 9 to 32, with a size range of 200 - 1500 bp. The average numbers of fragments per primer and polymorphic fragments per primer were 18.94 and 17.17, respectively. Polymorphism information content (PIC) values ranged from 0.23 to 0.37 with an average of 0.31 across all the genotypes. Pair wise coefficients of ISSR-based genetic similarity between all genotypes ranged from 0.70 to 0.99 with an average of 0.86, suggesting quite narrow genetic base ofmungbean and blackgram in Thailand that might limit continued breeding success. UPGMA analysis based on ISSR exhibited 2 major clusters; cluster I containing all mungbean genotypes and cluster II containing all blackgram genotypes. It appeared that ISSR was more effective for classification at the species level although no clear separation at the subspecies level was found. All 22 mungbean and blackgram genotypes can be effectively distinguished by only 6 ISSR primers with the highest PIC values, suggesting the applicability of ISSR analysis for variety identification

Mutualistic co-evolution of T3SSs during the establishment of symbiotic relationships between Vigna radiata and Bradyrhizobia

This study supports the idea that the evolution of type III secretion system (T3SS) is one of the factors that controls Vigna radiata-bradyrhizobia symbiosis. Based on phylogenetic tree data and gene arrangements, it seems that the T3SSs of the Thai bradyrhizobial strains SUTN9-2, DOA1, and DOA9 and the Senegalese strain ORS3257 may share the same origin. Therefore, strains SUTN9-2, DOA1, DOA9, and ORS3257 may have evolved their T3SSs independently from other bradyrhizobia, depending on biological and/or geological events. For functional analyses, the rhcJ genes of ORS3257, SUTN9-2, DOA9, and USDA110 were disrupted. These mutations had cultivar-specific effects on nodulation properties. The T3SSs of ORS3257 and DOA9 showed negative effects on V. radiata nodulation, while the T3SS of SUTN9-2 showed no effect on V. radiata symbiosis. In the roots of V. radiata CN72, the expression levels of the PR1 gene after inoculation with ORS3257 and DOA9 were significantly higher than those after inoculation with ORS3257 omega T3SS, DOA9 omega T3SS, and SUTN9-2. The T3Es from ORS3257 and DOA9 could trigger PR1 expression, which ultimately leads to abort nodulation. In contrast, the T3E from SUTN9-2 reduced PR1 expression. It seems that the mutualistic relationship between SUTN9-2 and V. radiata may have led to the selection of the most well-adapted combination of T3SS and symbiotic bradyrhizobial genotype