Abstract
Gibberellins induce gene-expression for hydrolytic enzymes in germinated cereal aleurones. Products of GA-primary genes, such as GAMYB, act as key molecules leading to transcription-activation of these genes. To dissect true mechanisms of GA-mediated gene-expression, it would be critical to understand how GA-primary genes themselves are regulated. Previous analyses indicated that 5'-upstream portion from GA-primary genes could not confer GA-responses. Several regulatory domains were located throughout gene-region. The most notable finding was enhancer-activities present in a large 1st intron. In Arabidopsis, intron-enhancers have been identified in floral-control-genes, AG and FLC, in which large intron should not only contribute to proper gene-expression, but also associate with gene-silencing by covalent modifications of DNA and histone. These evidences allow us to suggest that primary event caused by GA-action might be recruitment of primary genes from silent chromatin region. Based on this assumption, we have been investigating DNA-methylation-status of GA-primary genes, using bisulfite sequence method.
