Endogenous gibberellin A1 level and α-amylase activity in germinating rice seeds

Abstract

The role of endogenous gibberellin A1 (GA1) in the induction of α-amylase activity was investigated during germination of rice (Oryza sativa L.) seeds. The level of endogenous GA1 and the α-amylase activity in the seeds of normal rice, cv. Nipponbare, increased simultaneously from 3 days after the imbibition of water. The α-amylase activities in the dwarf rice, cv. Waito-C and Tan-ginbozu, were less than that in the normal rice. The level of endogenous GA1 and α-amylase activity were decreased in proportion to the concentration of a growth retardant, uniconazole. The retardation in α-amylase activity caused by the treatment of uniconazole was recovered by the application of exogenous GA1. These results indicate that the endogenous GA1 biosynthesized de novo regulates α-amylase production in germinating rice seeds.