The Vigna angularis complex: Genetic variation and relationships revealed by RAPD analysis, and their implications for in situ conservation and domestication

The present study, using RAPD analysis, was undertaken to characterize gene tic variation in three forms of V. angularis, cultivated, wild and weedy fo rms, and their relationships. The materials used consisted of 171 individua ls (plants) or cultivars from 23 populations including 5 wild populations, 6 weedy populations, 6 cultivated populations and 6 populations with plants having wild and weedy or intermediate morphology, denoted here as complex populations. The materials used were collected on Honshu Island, Japan and seeds collected directly from the field were germinated for DNA extraction. In addition, 6 landrace accessions of V. angularis from the genebank were also analyzed. Genetic variation was highest in the wild form (H-g= 0.132; GD = 0.388), followed by the weedy form (H-g= 0.124; GD = 0.341) and the le ast in the cultivated form (H-g= 0.079; GD = 0.274). Intra-population genet ic variation was high in the weedy and in the wild populations. However, in ter-population was greater than intra-population genetic variation for all groups of populations studied in the V. angularis complex. 93% of the total diversity in the present study was exhibited by plants from complex popula tions and specific RAPD bands were found in these populations. Our results provide evidence that complex populations would be a logical focus for effo rts to conserve the V. angularis complex in situ. Our results suggest that weedy populations are usually an ecotype of the wild form adapted to a diff erent habitat.