Regulation and functional analysis of the OsDREB2B gene encoding a transcription factor involved in abiotic-stress-responsive gene expression

Abstract

DREBs are transcription factors that interact with a cis -acting DRE sequence and activate expression of downstream genes involved in abiotic stress response and tolerance in Arabidopsis thaliana. There are four DREB2 homologues in rice, and OsDREB2B is genetically close to other DREB2-type genes in monocots. OsDREB2B transcripts were accumulated by low temperature, high temperature and salt stresses in rice seedlings. OsDREB2B produced two forms of transcripts, and quantitative real-time PCR analyses demonstrated that the functional transcription form of OsDREB2B was significantly induced by stresses compared with the other form. The OsDREB2B protein translated from the functional transcription form mRNA was localized to nucleus and we found that the protein exhibits high transactivation activity by using transient transactivation experiments, suggesting that protein modification is not required for activation of OsDREB2B. We are now also analyzing the target genes of OsDREB2B using transgenic Arabidopsis and rice.