IDENTIFICATION OF GIBBERELLIN-A(4) IN PISUM-SATIVUM L AND THE EFFECTSOF APPLIED GIBBERELLIN-A(9), GIBBERELLIN-A(4), GIBBERELLIN-A(5) AND GIBBERELLIN-A(3) ON THE LE MUTANT

Gibberellin A(4) (GA(4)) was identified for the first time in the gard en pea (Pisum sativum) L.), by gas chromatography-mass spectrometry. H owever, in wild-type shoots the level of GA(4) was only about 6% of th e level of GA(1), and it is therefore unlikely that GA(4) plays a majo r role per se in the control of pea stem elongation. In shoots of the le mutant, GA(4) was not detected, while the level of GA(9) was approx imately twice that found in the wild-type. The Ie mutation also marked ly reduced the elongation response to applied GA(9). It appears, there fore, that in Pisum the le mutation blocks the 3 beta-hydroxylation of GA(9) to GA(4), in addition to the 3 beta-hydroxylation of GA(20) to GA(1). In contrast, the le mutation did not reduce the response to app lied GA(5), suggesting the step GA(5) to GA(3) is not catalysed by the enzyme controlled by the Le gene. The step GAS to GA(3) was confirmed in peas by metabolite analysis after treatment with deuterated GA(5).