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Planta. 1984 Apr;160(5):455-63. doi: 10.1007/BF00429763.

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

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Department of Botany, University of Tasmania, 7001, Hobart, Tasmania, Australia.


The influence of the Na and Le genes in peas on gibberellin (GA) levels and metabolism were examined by gas chromatographic-mass spectrometric analysis of extracts from a range of stem-length genotypes fed with [(13)C, (3)H]GA20. The substrate was metabolised to [(13)C, (3)H]GA1, [(13)C, (3)H]GA8 and [(13)C, (3)H]GA29 in the immature, expanding apical tissue of all genotypes carrying Le. In contrast, [(13)C, (3)H]GA29 and, in one line, [(13)C, (3)H]GA29-catabolite, were the only products detected in plants homozygous for the le gene. These results confirm that the Le gene in peas controls the 3β-hydroxylation of GA20 to GA1. Qualitatively the same results were obtained irrespective of the genotype at the Na locus. In all Na lines the [(13)C, (3)H]GA20 metabolites were considerably diluted by endogenous [(12)C]GAs, implying that the metabolism of [(13)C, (3)H]GA20 mirrored that of endogenous [(12)C]GA20. In contrast, the [(13)C, (3)H]GA20 metabolites in na lines showed no dilution with [(12)C]GAs, confirming that the na mutation prevents the production of C19-GAs. Estimates of the levels of endogenous GAs in the apical tissues of Na lines, made from the (12)C:(13)C isotope ratios and the radioactivity recovered in respective metabolites, varied between 7 and 40 ng of each GA per plant in the tissue expanded during the 5 d between treatment with [(13)C, (3)H]GA20 and extraction. No [(12)C]GA1 and only traces of [(12)C]GA8 (in one line) were detected in the two Na le lines examined. These results are discussed in relation to recent observations on dwarfism in rice and maize.


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