Abstract
Cell-free systems were prepared from germinating seed and seedlings of Phaseolus coccineus. Gibberellin A4 (GA4)-metabolising activity was detected in vitro using preparations from roots, shoots and cotyledons of germinating seed, but only up to 24 h after imbibition. Cell-free preparations from cotyledons converted [3H]GA4 to GA1, GA34, GA4-glucosyl ester and a putative O-glucoside of GA34, and, in addition converted [3H]GA1 to GA8. Preparations from embryo tissues contained 2β-hydroxylase activity, converting [3H]GA4 to GA34 and [3H]GA1 to GA8.
The presence of GA-metabolising enzymes was also indicated by in-vivo feeds of [3H]GA4 to epicotyls of intact 4-d-old seedlings, which resulted in the accumulation of GA1, GA8, GA3-3-O-glucoside, GA4-glucosyl ester, GA8-2-O-glucoside and a putative O-glucoside of GA34. Gibberellin A1 was the first metabolite detected, 15 min after application of [3H]GA4, but after 24 h most of the label was associated with GA8-2-O-glucoside. Over 90% of the recovered radioactivity was found in the shoot. Within the shoot, movement was preferentially acropetal, and was not dependent upon metabolism of the applied [3H]GA4.
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Abbreviations
- DEAE:
-
diethylaminoethyl
- GAn :
-
gibberellin An
- GPC:
-
gel permeation chromatography
- HPLC-RC:
-
high performance liquid chromatography-radio counting
- S-1:
-
1000·g supernatant
- UDP:
-
uridine 5′-diphosphate
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Turnbull, C.G.N., Crozier, A. Metabolism of [1,2-3H]gibberellin A4 by epicotyls and cell-free preparations from Phaseolus coccineus L. seedlings. Planta 178, 267–274 (1989). https://doi.org/10.1007/BF00393203
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DOI: https://doi.org/10.1007/BF00393203