ISOZYME VARIATION IN TARO (COLOCASIA-ESCULENTA (L) SCHOTT) FROM ASIA AND OCEANIA

Isozyme variation was studied in 1,417 cultivars and wild forms of taro collected in Asia and Oceania. Seven polymorphic enzyme systems (MDH, IDH, PGI, 6-PGD, ME, SkDH, and ADH) revealed 143 isozyme phenotypes, or zymotypes, each uniquely characterized by the presence or absence of 56 electromorphs. Results showed greater isozyme variation in Asia than in Oceania, with Indonesia being the area of greatest diversity. No correlations were found between zymotypes and morphotypes or ploidy levels (as described by other investigators). Multivariate analyses of the isozyme data indicated that the majority of the Indonesian cultivars were different from the Philippine and Oceanian taro cultivars. Oceanian cultivars constituted a continuum of clusters and are thought to have originated from a narrow genetic base introduced from Indonesia. If taro breeding is to have any future in Oceania, it is important to exchange genotypes to broaden the base of existing breeding programmes.