MORPHOLOGICAL VARIATION OF CORMS IN PLANTS REGENERATED FROM CALLUSES OF TARO (COLOCASIA ESCULENTA SCHOTT)

We investigated morphological characteristics of plants regenerated from calluses of taro (Colocasia esculenta Schott) ‘Yatsugashira’. Calluses were formed by culturing etiolated stem segments on Murashige and Skoog's (MS) medium supplemented with 30 g L^-1 sucrose, 0.1 or 1 mg L^-1 NAA or 2,4-D, respectively, and 1 mg L^-1 2ip. Adventitious shoots were regenerated from calluses by transfer to MS medium supplemented with 30 g L^-1 sucrose, with or without 2 mg L^-1 BA. These shoots formed roots after transfer to MS medium supplemented with 30 g L^-1 sucrose. ‘Yatsugashira’ has no distinct mother corm; the corms and cormels form a conglomerate. However, 6% o f shoot apices-derived calluses and 89% of etiolated stem-derived calluses generated into mutants that had a distinct large mother corm surrounded by smaller cormels (S-type). This mutation occurred irrespective of the type or concentration of plant growth regulator included in the callus induction or regeneration media. Etiolated stem segments of both an S-type and a C-type plant were re-cultured and regenerated plants. All of the regenerated plants from both plant types were morphologically similar to their corresponding mother plants. These results indicate that the morphology of mother corms in ‘Yatsugashira’ is highly mutable, but that stable characteristics can be obtained by the formation of adventitious, callus-derived shoots.