Discovery and validation of SSR marker-based QTL governing fresh pod yield in dolichos bean (Lablab purpureus L. Sweet)

Identification and validation of quantitative trait loci (QTL) governing desired phenotype of target trait is a prerequisite to implement marker-assisted selection in any crop including dolichos bean. Under this premise, we used two mapping populations (MPs) to detect and cross population validate QTL controlling fresh pod yield. One of the MPs consisted of F₂ individuals (MP1) derived from crossing two elite genotypes, the second MP consisted of random RILs (MP2) derived from a different pair of elite genotypes. The MP1 and MP2 were genotyped using polymorphic 86 and 91 SSR markers, respectively and linkage maps were constructed using QTL IciM mapping software. The MP1 and MP2 were phenotyped during 2021 and 2017 rainy and post rainy seasons, respectively for fresh pod yield plant^-1 following two-replicated simple lattice design. QTL maps were developed in MP1 and MP2 using genotype and phenotype data. Our results indicated that the estimates of total map length, average map length per linkage group (LG) and average inter-marker distance in MP2 were greater (by at least 1.5 times) than those in MP1. While seven QTLs were detected in MP1, six were detected in MP2 with three QTL exhibiting positive and additive minor effects for fresh pod yield plant^-1. We also detected one common minor positive effect QTL across two seasons in MP2 and significant epistatic QTL, whose main effects were non-significant. One each of the seven and six QTL-linked SSR markers detected in MP1 and MP2, respectively were cross-population validated. The implications of these results are discussed in relation to strategies to breed dolichos bean.