Regulation and Functional Analysis of the OsDREB2B gene Encoding a Transcription Factor Involved in Abiotic-stress-responsive Gene Expression

Abstract

A transcription factor DREB2A interacts with a cis-acting DRE sequence and activates expression of downstream genes involved in drought and salt stress response in Arabidopsis thaliana. OsDREB2B is one of DREB2 homologues in rice, and it has high homology to HvDRF and ZmDREB2A. OsDREB2B transcripts were accumulated by low temperature, dehydration and salt stresses. 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. Using transient transactivation experiments we found that functional transcription form of OsDREB2B exhibited high transactivation activity in Arabidopsis protoplasts but the other form did not. These data suggest that splicing mechanisms play an important role in regulating OsDREB2B gene activity under stress conditions. We are also analyzing the function of OsDREB2B using transgenic Arabidopsis and rice.