POPULATION STRUCTURE AND GENETIC DIVERSITY ANALYSIS OF INDONESIAN YARDLONG BEAN (Vigna unguiculata subsp. sesquipedalis)

The identification of population structure and genetic diversity is an important step toward enabling the effective and efficient genetic improvement of crop species. We report the analysis of population structure and genetic diversity of Indonesian yardlong bean (Vigna unguiculata subsp. sesquipedalis) genotypes based on inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon microsatellite amplified polymorphism markers (REMAP). Results showed that 52% (11 out of 21) of the markers that were applied in this study were useful for the identification of DNA polymorphism in yardlong bean. STRUCTURE analysis revealed two subpopulations, i.e., P1 and P2. Principal coordinate analysis and neighbor-joining cluster analysis were performed to investigate subpopulation differentiation. Significant differentiation was detected in P2, whereas no significant differentiation was observed in P1. The results corroborated the findings of STRUCTURE analysis. Although broad morphological diversity was present across genotypes, narrow genetic diversity was observed at the DNA level. These findings suggested that increasing genetic diversity to obtain favorable genotypes should be emphasized in the genetic improvement of yardlong bean.