Abstract
To study mechanisms underlying dormancy, we conducted microarray analysis to compare gene expression profiles in dormant organs before and after release from dormancy. A statistical cis element search revealed two common elements were enriched in up-regulated gene promoters after release from dormancy both in bud and seed. In contrast, sugar-repressive element and ABA-responsive element were rich in the down-regulated gene promoters in bud and seed, respectively. Next, to control endogenous ABA contents in seed, we tried to identify ABA 8'-hydroxylase, a committed step in major ABA catabolism. Among 272 Arabidopsis P450s, we performed phylogenetic and gene expression analyses to narrow down the candidate genes. Functional assay in yeast revealed that CYP707A genes encode ABA 8'-hydroxylases. The knockout lines of the CYP707A2 gene exhibited hyperdormant seed resulting from a significant ABA accumulation. These demonstrated that these genes might be powerful tools to control dormancy in the seed.
