Molecular Mechanism Of Transcriptional Regulation In Response To Reactive Oxygen Species In Arabidopsis Thaliana

Reactive oxygen species (ROS) has been characterized as an important signal molecule that mediates many developmental and physiological processes in plants, which include biotic and abiotic stress responses, stomotal movement, programmed cell death, growth and development. ROS also plays a global role in gene transcription. So far, details of the ROS responsive transcriptional network are still largely unknown.To gain insight into the coordination of gene expression profiles under abscisic acid (ABA) and H2O2 applications, global changes in gene expression in response to ABA and H2O2 in Arabidopsis seedlings were investigated by microarray analysis.459 transcripts were found to be significantly increased, whereas another 221 decreased following H2O2 treatment compared with control. These results suggest the global role of H2O2 in gene transcription. The transcriptional responses induced by the application of exogenous ABA and H2O2 overlapped substantially. Promoters of ROS up-regulated genes were selected for a bioinformatics search to identify the potential transcription factor binding sites responsible for ROS induced gene expression, and four of eight potential ROS responsive cis-elements (ROEs) are sufficient to confer a rapid increase of luciferase under H2O2 and MV treatment indicated their roles in ROS responsive gene transcription.We also found that an AP2/EREBP transcription factor ERF6 could bind to the ROE8 specially. Co-expression of ERF6 effector enhanced the expression of ROE8 driver luciferase gene, we also found that ERF6 interacted physically with MPK6 in vitro and in vivo, and also served as a substrate of MPK6. Two Ser residues, Ser 266 and Ser 269 were the putative phosphorylation site of ERF6. After application of H2O2, phosphorylation by MPK6, ERF6 relocalizes from cytoplasm to the nucleus. Expression of ROS responsive genes is strongly up-regulated in 35S-ERF6WT and 35S-ERF6DD transgenic plants. Furthermore, growths of 35S-ERF6WT and 35S-ERF6DD seedlings are more sensitive to H2O2 treatment than WT or 35S-ERF6AA transgenic plants. Immunoprecipitation results indicated that H2O2 treatment and SS to DD mutation also increased the stability of ERF6-MPK6 complex. Based on those results, the MPK6-ERF6 pathway has established that it mediated the ROS responsive transcription and seedling growth regulation.In this work, H2O2 responsive gene transcription was compared at genomic ranges and potential ROS responsive cis-elements were identified. The function of ROE8 binding protein ERF6 in controlling the ROS responsive gene expression was also characterized. We found that H2O2 responsive gene expression partly dependent on ROS-MPK6-ERF6 pathway. These data may provide new insight into ROS responsive gene regulation mechanism.