Promoter Analysis of OsChia4a That is Regulated by RERJ1, a Jasmonic acid-responsive Transcription Factor in Rice

Abstract

Jasmonic acid (JA) is a plant hormone that acts as a secondary signaling molecule in plant defense responses. RERJ1 that encodes a bHLH transcription factor was isolated as a JA-responsive gene from rice suspension cells. Previously, we reported that RERJ1 functions as a transcriptional activator and the expression of OsChia4a, which encodes class 4 chitinase, was induced in a RERJ1-dependent manner.
Here, we identified a JA-responsive cis element in the promoter region of OsChia4a by reporter-gene assay. The deletion analysis showed that the region from -515 to -265 bp in the promoter contains JA-responsiveness, and we found that the region contains three E-boxes. Subsequent mutation analysis of three E-boxes indicated that an E-box at -448 to -443 bp is essential for responding to JA and also for RERJ1-dependent expression of OsChia4a. Now, we are analyzing the binding of RERJ1 to this E-box by chromatin immunoprecipitation.