Internode length inPisum sativumL. The kinetics of growth and [3H]gibberellin A20metabolism in genotypena Le
✍ Scribed by Timothy J. Ingram; James B. Reid; Jake MacMillan
- Publisher
- Springer-Verlag
- Year
- 1985
- Tongue
- English
- Weight
- 943 KB
- Volume
- 164
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
The relationship between shoot growth and [3H]gibberellin A/o (GA2o) metabolism was investigated in the GA-deficient genotype of peas, na Le. [17-13C, 3H2]gibberellin A/o was applied to the shoot apex and its metabolic fate examined by gas chromatographic-mass spectrometric analysis of extracts of the shoot and root tissues. As reported before, [13C, 3Hz]GA1, [13C, 3H2]GA s and [~3C, 3Hz]GA29 constituted the major metabolites of [13C, 3Hz]GA2o present in the shoot. None of these GAs showed any dilution by endogenous 12C-material. [13C, 3Hz]GA29-catabolite was also a prominent metabolite in the shoot tissue but showed pronounced isotope dilution probably due to carry-over of endogenous [12C]GAz9-Catabolite from the mature seed. In marked contrast to the shoot tissue, the two major metabolites present in the roots were identified as [~3C, 3Hz]GA scatabolite and [13C, 3Hz]GA29-catabolite. Both of these compounds showed strong dilution by endogenous 12C-material. Only low levels of [13C, 3H2]GA1, [13C, 3Hz]GA8, [13C, 3Hz]GA20 and [a3C, 3H2]GA29 accumulated in the roots. It is suggested that compartmentation of GA-catabolism may occur in the root tissue in an analogous manner to that shown in the testa of developing seeds. Changes in the levels of [lfl,30~-3Hz]GA20 metabolites over 10 d following application of the substrate to the shoot apex of genotype na Le confirmed the accumulation of [3H]GA-catabolites in the root tissues. No evidence was obtained for catabolic loss of [3H]GA20 by complete oxidation or conversion to a methanol-inextractable form. The results indicate that the root system may play an important role in the regulation of biologically Abbreviations: GA n = gibberellin A n; GC-MS = gas chromatography-mass spectrometry; HPLC=high-pressure liquid chromatography active GA levels in the developing shoot of Na genotypes of peas.