Metabolism of Tritiated Gibberellin A9 by Shoots of Dark-grown Dwarf Pea, cv. Meteor

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Abstract
Tritium-labeled gibberellin A9 (3H-GA9) was metabolized by etiolated shoots of dwarf pea (Pisum sativum cv. Meteor) to GA20, GA10, 2,3-dihydro-GA31, and a number of highly polar, acidic GA-like substances. Identifications were made by gasliquid radiochromatography and combined gas chromatography-mass spectrometry. Kinetic studies showed that GA30 and 2,3-dihydro-GA31 were produced within 5 hours following 3H-GA9 application to pea shoots. The polar GA-like substances were produced between 5 and 10 hours after 3H-GA9 application. Levels of GA10 increased with time, and since no GA10 was produced during the purification procedures, GA10 was, in all probability, produced from 3H-GA9 within the plant tissue. The radioactive interconversion products produced by pea from 3H-GA9 have chromatographic properties similar to biologically active GA-like substances present in etiolated shoots of dwarf pea. Large scale applications of 3H-GA9 with very low specific activity to etiolated pea shoots showed that the radioactivity of the interconversion products was correlated exactly with biological activity as assayed by dwarf rice (Oryza sativa cv. Tan-ginbozu).