Genetic diversity and systematic relationships in sweetpotato (Ipomoea batatas (L.) Lam.) and related species as revealed by RAPD analysis

Summary Fifteen 10mer primers, in combination with the Stoffel fragment, were used to detect random amplified polymorphic DNA (RAPDs) among 26 accessions of sweetpotato (I. batatas (L.) Lam.) from Oceania, Peru, the Philippines, and the United States and between 8 Ipomoea species from section Batatas. Phenetic and principal coordinate analysis of the 56 polymorphisms detected within the hexaploid I. batatas clearly delineated the South Pacific and the Peruvian sweetpotato lines. The two U.S. cultivars clustered with the Oceanic materials. Cladistic and phenetic analysis of 8 Ipomoea species supports previously published phylogenies based on morphological and RFLP data. Among the species examined, I. tabascana, I. trifida and the tetraploid forms of I. batatas from Mexico and Ecuador, including I. batatas var. apiculata, are the taxa most closely related to the cultivated hexaploid I. batatas. These findings support the utility of RAPD markers for evaluating genetic diversity in sweetpotato and for establishing taxonomic and evolutionary relationships in Ipomoea.