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

Abstract

DREB2s 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 five DREB2 homologues in rice and they are called OsDREB2 genes. Among them, OsDREB2B is closely related to other DREB2-type genes in monocots. OsDREB2B protein exhibited higher transactivation activity than other OsDREB2s in transient transactivation assays. OsDREB2B produced two forms of transcripts, and the functional transcript of OsDREB2B was accumulated by low temperature, high temperature, drought and high salinity stresses in rice seedlings. Some drought- or high-temperature-stress inducible genes were induced in transgenic Arabidopsis expressing OsDREB2B ectopically. These data suggested that OsDREB2B functioned as a DREB2-type transcription factor. We are now analyzing the target genes of OsDREB2B using transgenic rice.