GENETIC-CONTROL OF 4 ENZYMES IN DIPLOID TARO, COLOCASIA-ESCULENTA (L.) SCHOTT

In order to understand the genetic variation and relationship of tare, Colocasia esculenta (L.) Schott, isozyme analyses were initiated usin g fertile diploid tare accessions. Polyacrylamide gel electrophoreses were performed on leaf tissue of wild or cultivated tare accessions fr om Nepal and Thailand, and their progeny to determine genes controllin g four enzyme systems: alcohol dehydrogenase, esterase, leucine aminop eptidase and phosphoglucomutase. A total of nine loci with two or thre e alleles were discovered encoding the four enzymes in leaf tissue amo ng the materials used in this study. The isozymes at the two loci of a lcohol dehydrogenase and esterase were in a dimeric form. Observed seg regation ratios were generally not significantly different (P > .05) f rom expected Mendelian segregation ratios; however, distortions were o bserved at some loci and possible causes were discussed. These finding s suggest the presence of allelic variants in other enzyme systems and precise classification of a wide range of diploid tare based on alloz yme variations. Most of tare. cultivars are triploids, which are consi dered to have evolved from fertilization of unreduced gametes of a dip loid. The genetic analyses of isozymes on the diploids will provide us eful information to investigate genetic variation, genetic relationshi p and evolution of not only diploid but also triploid tare.