Assessment of Genetic Diversity in Winged Bean [<em>Psophocarpus Tetragonolobus</em> (L.) DC.] Accessions Using Morphological Traits and Microsatellite Markers

Abstract

Winged bean productivity and the potential to enhance food and nutrition security in sub-Saharan Africa are recurrently affected by several constraints, including but not limited to the lack of genetic improvement. The dearth of adequate information on the genetic diversity that guides the choice of progenitors’ selection among other advantages has been a major setback in planning appropriate improvement programs. This study assessed 15 winged bean accessions for genetic diversity using 10 quantitative traits and 10 microsatellites (SSRs) markers. These accessions were evaluated using RCBD with three replicates for two growing seasons. Ten plants constitute each accession during evaluation from where leaf samples were obtained for SSR marker genotyping. Phenotypic results revealed significant variation (p < 0.05) in the performances of the accessions for the measured traits. H2 estimates varied from 18.92% for seed length to 72.67% for seed weight per plant. Pod weight had a positive and significant correlation with pod length (0.53), pod width (0.70), and number of seeds per pod (0.64). However, the number of seeds per pod negatively correlated with days to maturity (-0.71). The number of seeds per pod was positively predicted by pod weight, seed thickness, and days to maturity. Cluster analysis revealed two genetic groups characterized by different traits. The ten SSRs revealed an average allele count of 4.2, gene diversity of 0.25, and polymorphic information content of 0.22. Analysis of molecular variance revealed within the population of 95% as compared to between population variance of 5%. Phylogeny analysis revealed two primary genetic groups from where five secondary genetic subgroups were identified and only three accessions (TPt-6, TPt-126, and TPt-48) showed genetic purity. This study provides the basis for further studies aimed at exploiting existing variations in winged bean germplasm for its improvement.