Internode length in Lathyrus odoratus. Effects of mutants l and lb on gibberellin metabolism and levels

Abstract

After the application of [13C3H]‐gibberellin A20 to wild‐type (tall) sweet peas (Lathyrus odoratus L.) labelled gibberellin A1 (GA1), GA8, GA29 and 2‐epiGA29 were identified as major metabolities by gas chromatography‐mass spectrometry after high performance liquid chromatography. By contrast in genetically comparable dwarf (II) plants only labelled GA29 and 2‐epiGA29 were produced in significant amounts, although evidence was obtained for trace amounts of labelled GA1 and GA8. The apical portions of dwarf plants contained 8–10 times less GA1 than those of tall plants but at least as much GA20 (measured using di‐deuterated internal standards). In conjunction with previous data these results strongly indicate that in genotype ll internode length is reduced and leaf growth altered by a reduction in GA1 levels attributable to a partial block in the 3β‐hydroxylation of GA20 to GA1.In contrast to dwarf plants, semidwarf plants (genotype lblb) contained more GA1 in the apical portion than wild‐type counterparts. This is consistent with the suggestion that lb alters some aspect of GA sensitivity.