QTL mapping in Vigna radiata × Vigna umbellata population uncovers major genomic regions associated with bruchid resistance

Abstract

Mungbean (Vigna radiata), genus Vigna, is an economically important legume crop that is valued for its protein-rich dry seeds. However, bruchid infestation causes severe threat to seed storage in terms of deterioration in quantity along with nutritional quality. A new resistance source was found in Vigna umbellata, a species that is cross compatible with mungbean. Thus, the objective of this study is to identify the quantitative trait locus (QTL) controlling the bruchid resistance in RIL (recombinant inbred line) population developed from a hybridization between VRM (Gg) 1 (V. radiata) and TNAU RED (V. umbellata). The RIL population was screened for bruchid resistance using the following traits, viz. per cent of seed damage (SD), the total developmental period (TDP) and per cent of adult emergence (AE) in 2017 and 2018. The QTL analysis of these traits using a genetic map composed of 538 single nucleotide polymorphism (SNP) markers covering 11 chromosomes detected 12 QTLs in over the 2 years. Among them, the QTLs on chromosomes 05 and 08, designated qSD05 and qAE08, respectively, were stably detected in both years. qSD05 exhibited large effects in both years and mapped to 1.58-Mb genomic region of the mungbean reference genome. Genome mining of this QTL region identified the likely candidate genes involved in bruchid resistance. The outcomes and QTLs found in this study may provide useful information for fine mapping, marker-assisted selection (MAS), gene cloning and breeding for the resistance to bruchids.