DISTRIBUTION OF GIBBERELLINS IN LATHYRUS-ODORATUS L AND THEIR ROLE INLEAF GROWTH

In sweet pea (Lathyrus odoratus L.) the mutant allele I reduced the le vel of gibberellin A1 (GA1) in expanding leaflets and resulted in smal ler, more oval leaflets compared with the wild type. The apical portio ns of 6-d-old wild-type (L) seedlings also contained less GA1 and prod uced smaller, more oval leaflets than did comparable 20-d-old L seedli ngs. Application of GA1 markedly altered leaflet shape and, at certain dosages, restored the wild-type shape and size to leaflets of the I ( dwarf) mutant. Taken together, these observations indicate that GA1 pe rforms a regulatory role in the control of leaf growth in this species . The levels of GA1 precursors in the wild type were also determined. Rapidly expanding internodes contained much more gibberellin A19 (GA19 ) than gibberellin A21 (GA21), whereas the opposite was true for expan ding leaflets. Although in entire apical portions of established seedl ings the level of GA20 exceeded that of GA19, apical portions of very young seedlings contained more GA19 than GA20. Basal stem tissue of es tablished seedlings also contained substantially more GA19 than GA20 o r GA1. Both stems and leaflets from the basal portion of the plant con tained much less GA20 and GA1 than did the rapidly expanding apical ti ssue. The implications of these results for the regulation of GA1 bios ynthesis are discussed.