Genetic diversity in yardlong bean (Vigna unguiculata ssp. sesquipedalis) and related Vigna species using sequence tagged microsatellite site analysis

A high level of genetic diversity was identified within 15 accessions of yardlong bean from Thailand, Bangladesh, China, Laos, Philippines and Taiwan using STMS analysis based on cowpea Vigna unguiculata ssp. unguiculata primer-pairs. Accessions clustered into three distinct groups, at a 0.67 coefficient of similarity, with no correlation to geographical origins. Three pairs of accessions appeared to be similar indicating that each pair was of the same accession and most likely originated from the same geographical location. STMS primers designed from the cowpea genome were highly transferable to other Vigna species. STMS analysis with these primers also revealed a very high level of variation between six Vigna species, which clustered into three groups at a 0.5 coefficient of similarity. Group A represented the African Vigna species yardlong bean and cowpea, while groups B (mungbean, blackgram and moth bean) and C (rice bean and adzuki bean) represented the Asian Vigna species.