Ipomoea

Abstract

Ipomoea is one of the largest and complex genera containing over 600 species of vines and shrubs and widely distributed throughout the world. A number of species of Ipomoea are of considerable importance either as medicinal or ornamental plants. Among the species within the genus Ipomoea series Batatas, 13 are closely related to cultivated sweetpotato, although its wild ancestor is not yet identified. Many in the series are diploid (x{\thinspace}={\thinspace}15), two are tetraploid (I. tiliacea and I. tabascana), and I batatas has both tetraploid and hexaploid races. The cultivated sweetpotato appears to be the only known hexaploid in the genus. The polyploid origin of sweetpotato and its exact relationships with regard to the genomes of wild Ipomoea species are not clearly understood. Some of the wild species are known to harbor desirable genes useful for sweetpotato improvement, including resistance to sweetpotato weevil. Strategies to utilize these species will be depending upon on our understanding of their evolutionary relationships with the hexaploid sweetpotato and other strategies for introgression of beneficial genes from wild to cultivated species. However, interspecific hybrids between sweetpotato and its related species are rare, mainly because of various degrees of cross- and self-incompatibility.