Internode length in Pisum : The Le gene controls the 3β-hydroxylation of gibberellin A20 to gibberellin A 1

Gibberellins in immature seeds and dark-grown shoots of Pisum sativum : Gibberellins identified in the tall cultivar Alaska in comparison with those in the dwarf Progress No. 9

Gibberellins (GAs) A17, A19, A20, A29, A44, 2βOH-GA44 (tentative) and GA29-catabolite were identified in 21-day-old seeds of Pisum sativum cv. Alaska (tall). These GAs are qualitatively similar to those in the dwarf cultivar Progress No. 9 with the exception of GA19 which does not accumulate in Progress seeds. There was no evidence for the presence of 3-hydroxylated GAs in 21 day-old Alaska seeds. Dark-grown shoots of the cultivar Alaska contein GA1, GA8, GA20, GA29, GA8-catabolite and GA29-catabolite. Dark-grown shoots of the cultivar Progress No.9 contain GA8, GA20, GA29 and GA29-catabolite, and the presence of GA1 was strongly indicated. Quantitation using GAs labelled with stable isotope showed the level of GA1 in dark-grown shoots of the two cultivars to be almost identical, whilst the levels of GA20, GA29 and GA29-catabolite were significantly lower in Alaska than in Progress No. 9. The levels of these GAs in dark-grown shoots were 10(2)- to 10(3)-fold less than the levels in developing seeds. The 2-epimer of GA29 is present in dark-grown-shoot extracts of both cultivars and is not thought to be an artefact.

Metabolism of gibberellins by immature barley grain

Gibberellins A1, A4, A9, A12-aldehyde, A20 and A51, each labelled with both a radioactive and stable isotope were fed to immature barley grain by injection into the endosperm. After 7 d, extensive metabolism of all substrates had occurred, and metabolites were identified by combined capillary gas chromatography-mass spectrometry. A proposed scheme of gibberellin metabolism in immature barley grain is presented.

Internode length in Zea mays L. : The dwarf-1 mutation controls the 3β-hydroxylation of gibberellin A20 to gibberellin A 1

[(13)C, (3)H]Gibberellin A20 (GA20) has been fed to seedlings of normal (tall) and dwarf-5 and dwarf-1 mutants of maize (Zea mays L.). The metabolites from these feeds were identified by combined gas chromatography-mass spectrometry. [(13)C, (3)H]Gibberellin A20 was metabolized to [(13)C, (3)H]GA29-catabolite and [(13)C, (3)H]GA1 by the normal, and to [(13)C, (3)H]GA29 and [(13)C, (3)H]GA1 by the dwarf-5 mutant. In the dwarf-1 mutant, [(13)C, (3)H]GA20 was metabolized to [(13)C, (3)H]GA29 and [(13)C, (3)H]GA29-catabolite; no evidence was found for the metabolism of [(13)C, (3)H]GA20 to [(13)C, (3)H]GA1. [(13)C, (3)H]Gibberellin A8 was not found in any of the feeds. In all feeds no dilution of (13)C in recovered [(13)C, (3)H]GA20 was observed. Also in the dwarf-5 mutant, the [(13)C]label in the metabolites was apparently undiluted by endogenous [(13)C]GAs. However, dilution of the [(13)C]label in metabolites from [(13)C, (3)H]GA20 was observed in normal and dwarf-1 seedlings. The results from the feeding studies provide evidence that the dwarf-1 mutation of maize blocks the conversion of GA20 to GA1.