Winged bean [Psophocarpus tetragonolobus (L.) DC.] is a vegetable legume crop. The center of origin, diversity and domestication of this crop are not known. In this study, we assessed the genetic diversity and population structure of 457 accessions of winged bean collected from six geographical regions (North, Northeast, East, West, and central, and South) in Thailand using 14 simple sequence repeat (SSR) markers. In total, the SSR markers detected only 55 alleles with an average of 3.9 alleles per locus. Observed heterozygosity was relatively high (0.15) and overall gene diversity was moderate (0.487). Gene diversity, allelic richness and observed heterozygosity in the six regions were comparable, while the estimated out-crossing rate was relatively high (16.4%). STRUCTURE analysis grouped the 457 winged bean accessions into three sub-populations. Neighbor-joining (NJ) analysis grouped all the accessions into two major clusters. Genetic groups identified by both STRUCTURE analysis and NJ analysis were unrelated to geographical origins. Principal coordinate analysis revealed no clear clustering of the winged bean accessions. Although genetic groups were not unrelated to geographical origins, most of the winged bean accessions with long pods (30 cm or higher in length) or having purple seed coats or purple young pods were grouped together. This suggested that the winged beans with long pods or with purple seed or purple young pods may have a single origin. Altogether, these results demonstrated that the genetic diversity of winged bean in Thailand was moderate with high genetic admixture. We argue that the high genetic admixture of the winged bean in Thailand is due to seed migration and relatively high outcrossing rate.

翼豆 [ Psophocarpus tetragonolobus(L.) DC.] 是一种蔬菜豆类作物。这种作物的起源、多样性和驯化中心尚不清楚。在这项研究中，我们使用 14 个简单序列重复 (SSR) 标记评估了从泰国六个地理区域（北部、东北部、东部、西部和中部和南部）收集的 457 份翅豆的遗传多样性和种群结构。总的来说，SSR 标记仅检测到 55 个等位基因，每个基因座平均有 3.9 个等位基因。观察到的杂合度相对较高 (0.15)，总体基因多样性中等 (0.487)。六个区域的基因多样性、等位基因丰富度和观察到的杂合性相当，而估计的异交率相对较高（16.4%）。结构分析将 457 个有翼豆种质分为三个亚群。邻接 (NJ) 分析将所有种质分为两大类。通过 STRUCTURE 分析和 NJ 分析确定的遗传组与地理起源无关。主坐标分析显示翼豆种质没有明显的聚类。尽管遗传组与地理起源并非无关，但大多数具有长豆荚（长度为 30 厘米或更高）或具有紫色种皮或紫色幼豆荚的有翅豆种质被归为一组。这表明具有长豆荚或紫色种子或紫色幼豆荚的翼豆可能具有单一来源。总之，这些结果表明泰国翼豆的遗传多样性中等，遗传混合度高。