The presence of GA9, GA19 and GA20 was demonstrated by gas chromatography/mass spectrometry (GC/MS) and the presence of GA44 strongly indicated by GC/MS in selected ion monitoring mode (GC/SIM) in extracts of shoots of light-grown tall peas (Pisum sativum L.). Using the rice seedling bioassay with cv. Tan-ginbozu, the levels of gibberellins in pea shoots were monitored from early shoot growth through to apical senescence in a tall pea line. Levels of activity corresponding to GA20, GA19 and GA44 remained relatively stable in the shoot despite reproductive development and apical senescence. The level of GA1-like activity increased to a maximum when the leaves had between 7 and 9 leaves expanded and decreased only with apical senescence. The na gene which blocks the production of biologically active gibberellins in shoots but not in developing seed, was also operative in pod walls, with na pods containing little or no significant gibberellin-like activity when compared to na pods at contact. This occurred despite the presence of relatively high levels of gibberellins in developing seed at the same time. The results suggest that there is little or no significant leakage of biologically active gibberellins from developing seed to pods or shoots. Extracts of pods of tall peas with Na contained low levels of gibberellin-like activity but like developing seed, contained little or no significant GA1-like activity despite the presence of significant GA1-like activity in shoot extracts of tall peas.
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W. C. Potts (1986) studied this question.