Distribution of Gibberellins in Lathyrus odoratus L. and Their Role in Leaf Growth.

In sweet pea (Lathyrus odoratus L.) the mutant allele l reduced the level of gibberellin A1 (GA1) in expanding leaflets and resulted in smaller, more oval leaflets compared with the wild type. The apical portions of 6-d-old wild-type (L) seedlings also contained less GA1 and produced smaller, more oval leaflets than did comparable 20-d-old L seedlings. Application of GA1 markedly altered leaflet shape and, at certain dosages, restored the wild-type shape and size to leaflets of the l (dwarf) mutant. Taken together, these observations indicate that GA1 performs 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 A20 (GA20), whereas the opposite was true for expanding leaflets. Although in entire apical portions of established seedlings the level of GA20 exceeded that of GA19, apical portions of very young seedlings contained more GA19 than GA20. Basal stem tissue of established seedlings also contained substantially more GA19 than GA20 or GA1. Both stems and leaflets from the basal portion of the plant contained much less GA20 and GA1 than did the rapidly expanding apical tissue. The implications of these results for the regulation of GA1 biosynthesis are discussed.