Geographical differentiation of Asian taro, Colacasia esculenta (L.) Schott, detected by RAPD and isozyme analyses

Geographical differentiation and phylogenetic relationships of Asian taros, Colocasia esculenta (L.) Schott, and related species were analyzed by rand om amplified polymorphic DNA (RAPD) and isozymes of 13 enzyme systems with special interest in the accessions from the Yunnan area of China, which sup posedly has served the secondary center of taro diversification and dispers al into the temperate Far East Asia. The RAPD analysis was found to be bett er suited for detecting genetic differences within taros and among its rela ted species. However, both RAPD and isozyme analyses estimated quite simila r genetic relationships within taros and between related species. Genetic d ifferentiation was evident in the taro accessions of Nepal, Yunnan and othe r Asian areas; but, phylogenetic relationships between the differentiated t aro groups were not clearly determined. When taro cultivation was introduce d to a new area, only a small fraction of genetic variability in heterogene ous taro populations was transferred possibly causing random differentiatio n among locally adapted taro populations. Some of the Yunnan and Japanese a ccessions were found to be direct descendants of the common triploid popula tion. Further analysis on taros from the eastern China and Korea is necessa ry to clarify the Yunnan's role in taro diversification and dispersal. The significant local differentiation in Asian taros was clearly demonstrated b y RAPD and isozyme analyses in this study, and the results of this study wi ll serve as a base to establish evolutionary and genetic relationships amon g Asian taros.