Abstract
We have been studying on GA signaling in rice. We found that SLR1, a repressor for GA signaling, is degraded in a GA-dependent manner through SCFGID2 complex. Recently, we showed that the phosphorylation of SLR1 is promoted by GA in gid2 and the phosphorylated SLR1 is specifically interacted with recombinant GST-GID2. Here, we will report the phosphorylation sites of SLR1 and the role of its phosphorylation.
By using 32P-labeled SLR1 in gid2 and transgenic plant, we found that the phosporylated amino acid is serine and the phosphorylation sites locate on both GA signal perception and regulatory domain. The phosphorylation was observed even under GA deficient condition and kinase inhibitors did not inhibit the degradation of SLR1. Furthermore, dephosphorylated SLR1 protein also bound to GID2 in vitro. These results indicate the phosphorylation of SLR1 protein is not essential for the interaction with GID2. (supported by PROBRAIN)
