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

The utility of inter simple sequence repeat (ISSR) DNA polymorphisms to dis tinguish taxa within the genus Vigna was investigated. Nineteen primers, mo st containing either a GA or CA repeat, generated amplification products th at 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 cohesiv e group and appeared to be most closely related to V. triphylla and V. reti culata. In contrast, ISSR analysis was not able to clearly differentiate su bgeneric divisions within Vigna. We attribute this loss of resolution at th e subgeneric level to the high rate of evolution of the sequences we examin ed. Several probable instances of misclassification or hybrid origin of an accession were identified.