Further Identification of Endogenous Gibberellins in the Shoots of Pea, Line G2

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Abstract
To interpret the metabolism of radiolabeled gibberellins A12-aldehyde and A12 in shoots of pea (Pisum sativum L.). the identity of the radiolabeled peaks has to be determined and the endogenous presence of the gibberellins demonstrated. High specific activity [14C]GA12 and [14C]GA12-aldehyde were synthesized using a pumplin endosperm enzyme preparation, and purified by high performance liquid chromatography (HPLC). [14C]GA12 was supplied to upper shoots of pea, line G2, to produce radiolabeled metabolites on the 13-OH pathway. Endogenous compounds copurifying with the [14C]GAs on HPLC were analyzed by gas chromatography-mass spectrometry. The endogenous presence of GA53, GA44, GA19 and GA20 was demonstrated and their HPLC peak identity ascertained. The 14C was progressively diluted in GAs further down the pathway, proportional to the levels found in the tissue and inversely proportional to the speed of metabolism, ranging from 63% in GA53 to 4% in GA20. Calculated levels of GA20, GA19, GA44, and GA53 were 42, 8, 10, and 0.5 nanograms/gram, respectively.