Opposing Effects of Gibberellin and Ethylene

Abstract

At gibberellin (GA) concentrations between 0. 1 and 10 mg/1, the presence of ethylene reduced the growth stimulation in the lettuce hypocotyl bioassay for GA. 0. 1 mg/l GA induced sufficient invertase in sugar beet (Beta vulgaris) tissue to produce 808 [mu]g of reducing sugar from the sucrose medium per disk. The amount released declined to 240 [mu]g per disk if ethylene were present. 10 mg/1 GA induced enough [alpha]-amylase in barley endosperm to liberate 1440 [mu]g of sugar while ethylene reduced the value to 936 [mu]g. The presence of ethylene depressed enzyme activity at each GA concentration, and also in the control in both sugar beet and barley.