Genetic diversity of domestic (Thai) and imported winged bean [Psophocarpus tetragonolobus (L.) DC.] cultivars assessed by morphological traits and microsatellite markers

Winged bean [Psophocarpus tetragonolobus (L.) DC.] is a neglected and underutilized crop in Thailand, and yet is locally important throughout much of Asia and in some parts of Africa. In Thailand, winged bean cultivars are landrace selections that are mainly grown in home gardens across the country. In this study, the genetic diversity and population structure of 60 domestic (Thai) and 64 imported winged bean accessions were assessed via their comparative morphological traits and 13 gene-based simple sequence repeat (SSR) markers. The 13 markers generated 36 alleles in total with an average of 2.77 alleles per marker, and overall gene diversity of 0.47. The gene diversity of the Thai and imported winged bean accessions was comparable with values of 0.42 and 0.49, respectively. The estimated out-crossing rate was relatively high, at 16.28%. STRUCTURE, phylogenetic, and principal coordinate analyses consistently revealed the separate yet intermingled attributes of several accessions, which demonstrated their similar genetic diversity of the Thai and imported winged beans. The Thai and imported winged bean populations were comparable in days to flowering, pod length and seed size. Majority of the Thai and imported winged bean accessions showed the same qualitative traits, including leaf shape, flower color, pod color and pod shape. These suggested the winged bean growers' similar preferences and selection of winged beans in different geographical regions. The admixture within the genetic base of the winged bean indicates the need for the management of future breeding programs.