Abstract
Seed dormancy and germination is controlled by two phytohormones, abscisic acid (ABA) and gibberellins (GAs). We have previously identified and characterized Arabidopsis mutants that show ABA-insensitive seed germination. One of the mutants, named chotto1 (cho1), carries a mutation in a gene encoding a seed-specific APETALA2 transcription factor. We found that the transcript levels of genes for gibberellin 3-oxidase, GA3ox1 and GA3ox2, were up-regulated by after-ripening treatment during imbibition of the wild-type seed (Col-0). In contrast, transcript levels of GA3ox1 and GA3ox2 were similarly high regardless of after-ripening treatment in cho1 seeds. These results indicated that GA3ox gene expression is de-repressed in cho1 independently of after-ripening treatment, and also that CHO1 negatively regulates the GA3ox gene expression. We will show recent results of simultaneous ABA/GA analysis in the presentation.
