¹College of Plant science&Technology, Huazhong Agriculture University, Wuhan , 430070, China。
²Shanghai Agrobiological Gene Center, Shanghai, 201106, China。
^*Corresponding authorLi-Jun Luo：Tel:(+8621)62200490; Fax:(+8621)62204010;Email:lijun@sagc.org.cn

Abstract
Drought stress is one of the most important constraints to rice production and yield stability in the rainfed regions. The DREB transcription factors play a critical role in plant development and abiotic stress responses and, therefore, represent attractive targets for a molecular plant breeding approach. According to the barley gene chip results and rice homologous analysis, a new DRE-binding protein gene OsDREB was isolated by RT-PCR from Oryza Sativa japonica seedlings. OsDREB has a open reading frame of 873bp, which encods 291 amino acid residues and was classified as a typical member of the AP2/EREBP family of DNA-binding proteins.
Expression pattern analysis of OsDREB gene under various stresses indicated that the transcript of OsDREB was induced in response to dehydration stress ,salt stress and ABA treatment, especially to cold stress(4℃). GUS stain in OsDREB promoter-GUS transgenic rices demonstrated that OsDREB expressed in different tissues and organs in different expression Levels. Assay of yeast one-hybrid system showed that OsDREB had transcriptional activation activity and could specifically bind to the DRE cis-element. To understand its function in drought stress, overexpression and suppression transformation of rice were performed. Preliminary Observation revealed overexpression of OsDREB improve salt and cold tolerance in rice compared to wild type rice under salt and cold stress. However, OsDREB double-strand RNA interference(RNAi) lines were found to be more sensitive to drought stress than the wild type. Together, these results indicated that OsDREB, as an active transcription factor, participates in a wide range of abiotic stress processes.

Key Words: OsDREB; stress tolerance; transcription factor