Genetic linkage map construction and identification of QTLs associated with agronomic traits in bambara groundnut (Vigna subterranea (L.) Verdc.) using DArTseq-based SNP markers

Bambara groundnut [Vigna subterranea (L.) Verdc.] is an underutilised, protein-rich and self-pollinating legume that can withstand high temperature and drought stress and is mainly grown in semi-arid Africa. In order to dissect the complexity of drought resistance and to use genomic tools for yield enhancement of bambara groundnut in response to drought stress, yield-related and morphological traits under drought-stressed (DS) and well-watered (WW) conditions were evaluated in the F-3 and F-4 segregating generations derived from a cross between two genotypes selected from landraces S19-3 (originally from Namibia) and DodR (originally from Tanzania). Significant quantitative trait loci (QTLs) for shoot dry weight (SDW) were mapped on LG10 accounting for 15.5% of the phenotypic variation explanation (PVE) under well-watered conditions and a putative quantitative trait locus (QTL) for the same trait mapped on LG10 with reduced PVE (10.10%) under drought-stressed conditions in the F-3 segregating population. Significant QTLs associated with the number of seeds per plant (NS), number of double-seeded pods per plant (NDP), seed weight per plant (SW) and pod weight per plant (PW) were mapped on LG4 (nearest marker: 4181663 and 4175954) with overlapping confidence intervals and explained 21.9%, 21.8%, 23.5% and 19.9% of the PVE, respectively, under well-watered conditions in the F-4 population, which could be considered as the major QTL involved in the control of these traits. Seven consensus QTLs for yield-related and morphological traits were mapped on LG2, LG3, LG4, LG7A and LG10. The study provides fundamental knowledge of QTLs associated with yield-related and morphological traits under drought-stressed and well-watered conditions in bambara groundnut, which is also essential for yield improvement of bambara groundnut in response to drought stress.