Gibberellins in dark- and red-light-grown shoots of dwarf and tall cultivars ofPisum sativum: The quantification, metabolism and biological activity of gibberellins in Progress no. 9 and Alaska

摘要

The stem growth in darkness or in continuous red light of two pea cultivars, Alaska (Le Le, tall) and Progress No. 9 (le le, dwarf), was measured for 13 d. The lengths of the first three internodes in dark-grown seedlings of the two cultivars were similar, substantiating previous literature reports that Progress No. 9 has a tall phenotype in the dark. The biological activity of gibberellin A20(GA20), which is normally inactive inle legeno-types, was compared in darkness and in red light. Alaska seedlings, regardless of growing conditions, responded to GA20. Dark-grown seedlings of Progress No. 9 also responded to GA20, although red-light-grown seedlings did not. Gibberellin A1was active in both cultivars, in both darkness and red light. The metabolism of 13C3HGA20has also been studied. In dark-grown shoots of Alaska and Progress No. 9 13C3HGA20is converted to 13C3HGA1, 13C3HGA8, 13CGA29, its 2α-epimer, and 13C3HGA29-catabolite. 13C3H Gibberellin A1was a minor product which appeared to be rapidly turned over, so that in some feeds only its metabolite, 13C3HGA8, was detected. However results do indicate that the tall growth habit of Progress No. 9 in the dark, and its ability to respond to GA20in the dark may be related to its capacity to 3β-hydroxylate GA20to give GA1. In red light the overall metabolism of 13C3HGA20was reduced in both cultivars. There is some evidence that 3β-hydroxylation of 13C3HGA20can occur in red light-grown Alaska seedlings, but no 3β-hydroxylated metabolites of 13C3HGA20were observed in red light-grown Progress. Thus the dwarf habit of Progress No. 9 in red light and its inability to respond to GA20may be related, as in other dwarf genotypes, to its inability to 3β-hydroxylate GA20to GA1. However identification and quantification of native GAs in both cultivars showed that red-light-grown Progress does contain native GA1. Thus the inability of red light-grown Progress No. 9 seedlings to respond to, and to 3β-hydroxylate, applied GA20may be due to an effect of red light on uptake and compartmentation o