Abstract
Rice SLR1 (SLENDER RICE 1) gene encodes a DELLA protein, which belongs to subfamily of GRAS protein superfamily and functions as a repressor of gibberellin (GA) signaling. SLR1 has been considered to be a sole DELLA-type GA-signal suppressor protein in rice. Using the rice DNA database, however, we identified a homologous sequence to SLR1, SLR1-like (SLRL), in the rice genome. SLRL does not have the DELLA motif but its primary structure is highly similar to the C-terminal portions of DELLA proteins. Overexpression of SLRL in transgenic rice plants induced a dwarf phenotype with increased level of OsGA20ox2 gene expression, indicating that SLRL also acts as a repressor of GA signaling. The expression of SLRL was positively regulated by GA level and preferentially occurred in reproductive organs. Based on these results, we discuss the functional role of SLRL in GA signaling.
This work was in part supported by PROBRAIN.
