Inter simple sequence repeat analysis of genetic relationships in the genus Vigna

The utility of inter simple sequence repeat (ISSR) DNA polymorphisms to distinguish taxa within the genus Vigna was investigated. Nineteen primers, most containing either a GA or CA repeat, generated amplification products that differed among the taxa examined. The ISSR polymorphisms produced by 15 of these primers were very effective for distinguishing taxa at the species level or below. The Vigna unguiculata accessions analyzed formed a cohesive group and appeared to be most closely related to V. triphylla and V. reticulata. In contrast, ISSR analysis was not able to clearly differentiate subgeneric divisions within Vigna. We attribute this loss of resolution at the subgeneric level to the high rate of evolution of the sequences we examined. Several probable instances of misclassification or hybrid origin of an accession were identified.