Quantitative trait loci (QTL) detection and validation of linked markers associated with yellow mosaic virus resistance in urdbean [Vigna mungo (L.) Hepper] in Andhra Pradesh

The YMD is one of the serious viral diseases in blackgram and is being transmitted by whitefly (Bemisia tabaci). The development of YMV resistant blackgram varieties is one of the important aspects for sustainable blackgram production. Marker assisted selection and genetic transformation could be utilized in developing YMV resistant blackgram genotypes.

We attempted to map the QTLs governing YMV resistance in blackgram employing parents i.e., PBG32 (susceptible) and PU31 (resistant). Parental polymorphic studies were conducted using 147 SSR markers and genotyping and phenotyping data were used for QTL mapping. The markers, CEDG097 and CEDG172 that flanked to qYMV1 QTL were validated in 25 blackgram genotypes.

SSR markers showed 16% polymorphism between the parents. By using F₂ genotypic data, genetic linkage map was constructed and total genetic map length observed was 335.47 cm. Single QTL (qYMV1) for YMV tolerance was detected and located between markers CEDG097 and CEDG172 with LOD score value of 2.76. The PVE by qYMV1 is 13.10% and the QTL is tightly linked (0 cM) to the left flanking marker CEDG97, which denotes a major QTL. Genotyping of the 25 known blackgram genotypes employing CEDG097 and CEDG172 markers, CEDG097 showed 91% linkage in known resistant and susceptible varieties to the YMV disease reaction and CEDG172 exhibited 74% linkage in known varieties to the YMV disease reaction. The resistance alleles (PU31 allele) of both markers i.e. CEDG097 and CEDG172 were recorded in VBN7, LBG922, LBG933 and TBG130-1 hence, these genotypes can be considered as potent YMV resistant varieties and also can be used as donor parents in resistance breeding programmes.