Expression of endogenous OsIPT and GA 20-oxidase genes in response to the induction of OSH15 function. A, Schematic representation of the OSH15:GR transgene. The chimeric gene consists of an in-frame fusion of the entire OSH15 cDNA and the steroid-binding domain of the human GR. This gene was driven by the rice actin promoter. B, Relative expression levels of OsIPT and GA 20-oxidase genes in 2-week-old OSH15:GR transgenic rice 24 h after 1 μm DEX treatment. C, Changes in the expression levels of OsIPT2, OsIPT3, OsGA20ox2, and OsGA20ox4 after DEX treatment. The ratio between each gene level and the histone H3 level obtained from DEX untreated control plants was arbitrarily set at 1.0. qRT-PCR was performed in triplicate and mean values with sd are shown.