MECHANISM OF ACTION OF GIBBERELLIC ACID: INHIBITION OF α-AMYLASE DEVELOPMENT DURING GERMINATION OF BARLEY BY CHLORAMPHENICOL AND ITS REVERSAL BY GIBBERELLIC ACID

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Abstract
Barley kernels germinated in water, in solutions of gibberellic acid (GA), in chloramphenicol sodium succinate (CAL), and in combinations of GA and CAL, for 5 days were analyzed daily to determine growth and α- and β-amylase, proteinase, and respiratory activities. Respiration, growth, and amylase activities were inhibited by CAL, but were accelerated by GA. Combined treatment of CAL and GA partially reversed the inhibitive effects of CAL on respiration and growth, but amylase development approached that of GA-treated seeds. No correlations were found between proteinase activity and respiration or α-or β-amylase activities. The significance of these findings with respect to α-amylase formation and mode of action of GA is discussed. It is suggested that α-amylase is synthesized during germination and that GA accelerates this synthesis.