Abstract
To classify cultivars of Japanese taro (Colocasia esculenta (L.) Schott), isozyme variations at the five loci, Gpi-2 of glucose-6-phosphate isomerase, Aat-1 and Aat-3 of aspartate aminotransferase, Skdh of shikimate dehydrogenase and Idh of isocitrate dehydrogenase, were examined in the 58 cultivars. Allele a at the Aat-3 was recognized specifically in all the examined triploid cultivars, and this allele clearly discriminated the triploid cultivars from the diploid ones. This suggests that these triploid cultivars did not originate as bud mutations or from crosses between diploid ones. Combinations of isozyme genotypes at the five loci divided the 58 cultivars into only 11 groups, which indicates that the Japanese cultivars originated from a relatively small number of progenitors. Isozyme variations in each of the 14 cultivar groups proposed by Kumazawa et al. (1956) were not recognized except those in the Akame and Kurojiku groups. Therefore, wide morphological variations between the cultivars in each of the cultivar groups seem to have occurred as bud mutations in many cases. Cultivars in the Akame and Kurojiku groups seem to have been derived from the several ancestral cultivars of different origins.
