Genetic similarities among cocoyam cultivars based on randomly amplified polymorphic DNA (RAPD) analysis

Eighteen cultivars of cocoyam (Xanthosoma spp.) and two cultivars of taro (Colocasia esculenta (L.) Schott) from the USDA/ARS germplasm collection were evaluated for genetic relatedness using RAPD data. Seven random primers generated 40 RAPD loci. Of the 18 cultivars screened, 11 (61%) were identical at all RAPD loci evaluated. A similarity matrix was constructed on the basis of the presence or absence of bands. Among cocoyam cultivars the genetic similarity ranged from 0.86 to 0.97 with a mean of 0.91. Cluster analysis identified two main clusters with some unexpected groupings. These data indicate that very little genetic variation exists within the accessions used in this study and that this Xanthosoma spp. collection is of limited value as a genetic resource.