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Plant Physiology 70:1614-1618 (1982) © 1982 American Society of Plant Biologists Metabolism of Tritiated Gibberellin A20 in Maize 1Department of Biology, University of Calgary, Calgary, Alberta T2N 1N4 Canada
After the application of 2.36 Curies per millimole [2,3-3H]gibberellin A20 (GA20) to 21-day-old maize (Zea mays L., hybrid CM7 x CM49) plants, etiolated maize seedlings, or maturing maize cobs, a number of 3H-metabolites were observed. The principal acidic (pH 3.0), ethyl acetate-soluble metabolite was identified as [3H]GA1 on the basis of co-chromatography with standard [3H]GA1 on SiO2 partition, high resolution isocratic elution reverse phase C18 high performance liquid chromatography and gas-liquid chromatography radiocounting. Two other acidic metabolites were identified similarly as [3H]GA8 and C/D ring-rearranged [3H]GA20, although gas-liquid chromatography radiocounting was not performed on these metabolites. Numerous acidic, butanol-soluble (e.g. ethyl acetate-insoluble) metabolites were observed with retention times on C18 high performance liquid chromatography radiocounting similar to those of authentic glucosyl conjugates of GA1 and GA8, or with retention times where conjugates of GA20 would be expected to elute. Conversion to [3H]GA1 was greatest (23% of methanol extractable radioactivity) in 21-day-old maize plants. In etiolated maize seedlings, the C/D ring-rearranged [3H]GA20-like metabolite was the major acidic product, while conversion to [3H]GA1 was low.
2 Present address: Faculty of Forestry, University of Toronto, Toronto, Ontario M5S 1A1. 3 Present address: C. S. I. R. O. Division of Horticulture, Merbein, Victoria, Australia. 4 To whom requests for reprints should be sent. 1 This work was supported by Natural Sciences and Engineering Research Council Grant A-2585 to R. P. P.
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