Tritiated gibberellins (GAs) A1, A4, A5and A20injected into the apical bud of light-grownPhaseolus coccineusL. seedlings were retained in the apical region and underwent little metabolism in 24 h. However, when injected into the hypocotyl, the 3HGAs were extensively metabolised and redistributed. All four GAs were equally effective in promoting subapical elongation in shoot explants irrespective of apical or basal application. The metabolism and export of 3HGA4by excised organs incubated for 24 h in buffer solution was both quantitatively and qualitatively different to that of the corresponding treated organs of intact plants, suggesting abnormal metabolic conditions in explants. 3HGAs applied to embryonic axes of germinating seeds were translocated into the cotyledons but no translocation in the reverse direction took place.
展开▼
