Abstract
We screened four semi-dominant semi-dwarf mutants of rice through MNU mutagenesis. Map-based cloning revealed that the dwarf phenotype in these mutants is caused by gain-of-function mutations in the N-terminal DELLA/TVHYNP region or the C-terminal GRAS domain of SLR1, and thus named them as Slr1-d1~4. A Gibberellin (GA) response test showed that Slr1-d are still responsive to GA, although at a reduced rate compared to the wild type. Additionally, degradation rate of SLR1-d protein were slower than SLR1. Since interaction between SLR1 and GA receptor GID1 is known to be essential for SLR1 degradation, interaction studies were conducted using the yeast two hybrid system, where reduced interaction abilities of the SLR1-d protein with GID1 were observed compared to SLR1. These results suggest that the semi-dwarf phenotype of Slr1-d mutants are caused by reduced interaction between Slr1-d protein and GID1, which lead to delayed degradation of SLR1-d protein.This work was supported by the Targeted Proteins Research Program and KAKENHI(18107001).
