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[ 14 C 4 ]GA 53 , [ 14 C 4 ]GA 44 , and [ 2 H 2 / 14 C 4 ]GA 19 were injected separately into seedlings of rice ( Oryza sativa) using a dwarf mutant ( d 35 ) that has low levels of endogenous gibberellins (GAs). After 8 h incubation, the shoots were extracted and the labeled metabolites were identified by full-scan gas chromatography–mass spectrometry (GC–MS) and Kovats retention indices (KRIs). Our results document the metabolic sequence, GA 53 →GA 44 →GA 19 →GA 20 and the presence of endogenous GA 53 , GA 44 , GA 19 , GA 20 and GA 1 . Previous metabolic studies have shown the presence of the step, GA 20 →GA 1 in rice. Taken together, the data establish in vegetative shoots of rice the presence of the early 13-hydroxylation pathway, a pathway that originates from GA 12 and leads to bio-active GA 1 . |
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