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Background: Blackgram [Vigna mungo (L.) Hepper] is an important food legume crop of India. Mungbean yellow mosaic virus (MYMV) disease is the major problem in blackgram. The disease can reduce seed yield upto 100% or even kill a plant infected at an early vegetative stage. The most effective way to prevent the occurrence of this disease is to develop genetically resistant cultivars of blackgram. However, a major difficulty in breeding MYMV disease resistant in blackgram is field screening for the virus disease. Hence identification of QTL followed by Marker-assisted selection (MAS) is highly useful for genetic improvement of crops. With this background, a study was made for identification as well as validation of quantitative trait loci (QTL) for MYMV disease resistance in blackgram.Methods: A total of 112 F2:3 lines were evaluated for MYMV disease resistance along with parents viz., MDU 1 (MYMV disease susceptible) and Mash 1008 (MYMV disease resistant) at the National Pulses Research Centre, Tamil Nadu Agricultural University, Vamban, Tamil Nadu during July-September 2018 under Augmented Design in the field. Each line was sown in one row of 3 m in length with a spacing of 30 cm as between row and 10 cm as within row. Susceptible genotypes CO 5 and MDU 1 were sown as disease spreader rows after every eight rows and also around the plots. The MYMV disease score was recorded on 60 DAS, by using phenotype rating scale from 1 (resistant) to 9 (highly susceptible), as suggested by Singh et al. (1995). The mean of each progeny was calculated and used as phenotypic data. A total of 525 SSR primers were used to test polymorphism between parents MDU 1 and Mash 1008. Genotyping was carried out for 112 F2:3 RILs of the cross MDU 1 x Mash 1008 with 35 polymorphic SSR markers. Linkage and QTL analyses were performed using QTL IciMapping (version 4.1.0.0) (Wang et al. 2016) and QGene 4.4.0 (Joehanes and Nelson 2008) respectively. Two mapping populations MDU 1 x Mash 114 and CO 5 x VBN 6 in F2:3 and F2 generations respectively were used in this study to validate the identified QTL regions.Result: QTL study indicated the presence of two major QTLs for MYMV disease score in LG 2 and LG 10 at 60 DAS with 20.90 and 24.90% of phenotypic variation respectively. Validation of these QTLs in two other mapping population indicated that QTL on LG 10 was validated with high phenotypic variation of 45.40-46.00%. Hence it may conclude that qmymv10_60 may be utilized for MAS/MABC with assured improvement on MYMV disease resistance in blackgram.

Background: Blackgram [Vigna mungo (L.) Hepper] is an important pulse crop occupying a unique position in Indian agriculture. Blackgram provides a major share of the protein requirement of the vegetarian population of the country. The crop is resistant to adverse climatic conditions and improves the soil fertility by fixing atmospheric nitrogen in the soil. Phenotypically stable genotypes are of great importance because the environmental conditions vary from season to season and year to year. Stable performance of blackgram genotypes across contrasting environments is essential for the successful selection of stable and high yielding varieties. Methods: A total of seven genotypes of blackgram were evaluated one season (Rabi - 2019) in three environments to study the G x E interaction for three traits.Result: Based on the stability analysis of Eberhart and Russell model, two genotypes viz., MDU 1 and NRIB 002 were found to be stable across the environments for seed yield. These genotypes had high seed yield with a unity regression coefficient and deviation from regression equal to zero.

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Plants dispense localised and systemic defense responses against biotic colonisers and plant resistance to pathogens depends upon timely recognition of pathogen infection and subsequent rapid activation of defense responses through signal transduction pathways. Induction of host defense responses involving compatible and incompatible interactions in tomato landrace, LE996, LE150 and LE1165 (Solanum lycopersicum), and wild relatives, Seijima Jeisei and I979 (S. hirsutum) genotypes, and early blight (EB) pathogen, Alternaria solani were studied. Accumulation patterns of different defense related proteins in resistant genotypes (LE996, Seijima jeisei and I979) and susceptible genotypes (LE150 and LE1165) are reported here. Challenge inoculation led to similar protein profiles in resistant genotypes yielding 11 proteins, unique are 14, 54, and 58 kD proteins that are absent with susceptible genotypes. Resistant genotypes accumulated more proteins well in advance, 6-h after challenge inoculation. Resistant genotype LE996 expressed 54%, 90%, and 52% enhanced enzymatic activity of peroxidase, polyphenol oxidase and phenylalanine ammonia lyase respectively than susceptible LE150 and correlated phenolics accumulation peaked 2-d after challenge inoculation. Activity gel assay indicated the unique expression of PO1 and PO2 in LE996 upon challenge inoculation. Significant increase in expression of chitinases (63%) and b-1,3-glucanase (71%) upon challenge inoculation than susceptible LE150 control was recorded. Western blotting indicated the unique presence of less than 30 kD chitinase in resistant LE996 and Seijima Jeisei and was absent in susceptible LE150. The results demonstrate the importance of pathogenesis-related (PR) proteins in EB resistance and their use as biochemical markers for genotype selection.