Abstract
Recent evidence provide a reliable concept that the gibberellin-signaling causes derepression of the repressible function of the DELLA protein. Working of the DELLA protein in the germinated cereal aleurones has been identified, but little is known as to how this protein contributes to the germination process. To delineate between the GA-signaling and nuclear functions, the effects of the DELLA protein on the expression of the GA-primary response genes, such as GAMyb and OsDof3, have been evaluated. Transient expression of reporter genes controlled by the upstream portion from the primary response genes showed the GA-dependency in transfected aleurone cells. 5'-deletions of the promoter regions gradually decreased the reporter activities, while keeping a constant responsibility to GA. Swapping of the 5'-upstrem regions with a general promoter CaMV35S further sustained the GA-responses. These findings suggest that the expression of the primary response genes should rest on regulatory elements apart from the 5'-upstream regions.
