Abstract
SLENDER RICE1 (SLR1) encodes an orthologous protein to GAI/RGA previously isolated as a repressor for GA response in Arabidopsis. Recent our studies have demonstrated that SLR1 represses the GA response in nuclei, but degrades rapidly when exposed to GA, suggesting that the GA response is de-repressed by the GA-dependent degradation of SLR1.
In order to investigate how GA signal is transmitted to degrade SLR1, we isolated two kinds of mutant named as GA-insensitive dwarf 1and 2 (gid1 and 2). Recently, we cloned the GID2 gene which encoded an F-box protein, a component of SCF ubiquitin ligase. In gid2 mutant, SLR1 protein was highly accumulated. There were two forms of the accumulated SLR1 in gid2, nascent and phosphorylated. These results indicate that SLR1 may be a target for the SCFGID2 and phosphorylation may trigger degradation of SLR1 in a similar manner as reported in yeast.
This work was in part supported by PROBRAIN.
