THE METABOLISM OF GIBBERELLIN A(20) TO GIBBERELLIN A(1) BY TALL AND DWARF MUTANTS OF ORYZA-SATIVA AND ARABIDOPSIS-THALIANA

The purpose of this study was to demonstrate the metabolism of gibberellin A(20) (GA(20)) to gibberellin A(1) (GA(1)) by tall and mutant shoots of rice (Oryza sativa L.) and Arabidopsis thaliana (L.) Heynh. The data show that the tall and dx mutant of rice and the tall and ga5 mutant of Arabidopsis metabolize GA(20) to GA(1). The data also show that the dy mutant of rice and the ga4 mutant of Arabidopsis block the metabolism of GA(20) to GA(1). [17-C-13,H-3]GA(20) was fed to tall and the dwarf mutants, dx and dy, of rice and tall and the dwarf mutants, ga5 and ga4, of Arabidopsis. The metabolites were analyzed by high-performance liquid chromatography and full-scan gas chromatography-mass spectrometry together with Kovats retention index data. For rice, the metabolite [C-13]GA(1) was identified from tall and dx seedlings; [C-13]GA(1) was not identified from the dy seedlings. [C-13]GA(29) was identified from tall, dx, and dy seedlings. For Arabidopsis, the metabolite [C-13]GA(1) was identified from tall, ga5, and ga4 plants. The amount of [C-13]GA(1) from ga4 plants was less than 15% of that obtained from tall and ga5 plants. [C-13]GA(29) was identified from tall, ga5, and ga4 plants. [C-13]GA(5) and [C-13]GA(3) were not identified from any of the six types of plant material.