A Novel RNA-Binding Protein Involves ABA Signaling by Post-transcriptionally Repressing .

The () repressed by ABA, salt and cold encodes a C2C2-type zinc finger protein in . The knock-out mutation in reduced the sensitivity of seed to ABA and salt stress during germination and post-germinative growth stages. In contrast, -overexpressing seedlings were more sensitive to ABA and salt compared to wild type plants. In the presence of ABA, the transcript levels of ABA signaling and germination-related genes including and were less induced in compared to WT. Interestingly, expression of encoding a protein phosphatase 2C protein were significantly up-regulated in mutants. By analysis, SRP1 was identified as a novel RNA-binding protein directly binding to 3'UTR of mRNA. Moreover, transient expression assay proved the function of SRP1 in reducing the activity of luciferase whose coding sequence was fused with the 3'UTR. Together, it is suggested that SRP1 is involved in the ABA signaling by post-transcriptionally repressing expression in .