Characterization of Rice Dwarf Mutant, GA Insensitive Dwarf 2 (gid2).

Abstract

We isolated a rice mutant, gid2, which showed a severe dwarf phenotype. The gid2 mutant showed very little response to exogenously treated GA. In gid2 mutants, level of bioactive GA was also accumulated.
Map-based cloning revealed that the GID2 gene encoded a putative F-box protein. 4.2Kb of DNA fragment containing the entire region of this gene complemented the gid2 phenotype. The deletion of nucleotides in two gid2 alleles introduced a novel stop codon in its coding region.
As previously reported, negative regulator of GA signaling, SLR1, is degraded by GA-dependent manner. In gid2, SLR1 was highly accumulated and GA-dependent degradation of SLR1 was not observed, whereas the comparatively small amount of SLR1 detected in wild-type plants degraded following GA treatment. These results suggest that GA-dependent degradation of SLR1 mediated by SCF complex involving GID2.
This work was in part supported by PROBRAIN.