Probing the Existence of an Alternative Gibberellin Receptor(s) in Rice Aleurone Cells

Many years after the discovery of GID1 as the GA receptor, the belief in the existence of GA-binding protein (GBP) in aleurone cells still persists. Actually, some recent reviews and textbooks still contain information about the possibility of an alternative GA perception mechanism mediated by GBPs. Thus, to finally clarify this issue, we examined the expression of GA-regulated genes using rice embryoless half-seeds of four kinds of GA signaling mutants, each one independently carrying mutated GID1, DELLA, and GA-related F-box, which are all encoded by single genes in rice, allowing for convenient study of the GA perception system. The comprehensive microarray analysis using these rice mutants revealed that all genes tested to be responsive to GA in the wild-type (WT) aleurone cells consistently did not respond to GA in the gid1 or slr1 mutant. All microarray experiments were performed according to the manufacturer’s manual. The Feature Extraction software (Agilent Technologies) was used to delineate and measure the Cy3 and Cy5 signal intensities of each spot in the array. The resulting data were normalized using the Variance-stabilizing normalization (VSN) algorithm.