<i>OsDREB</i> genes in rice, <i>Oryza sativa</i> L., encode transcription activators that function in drought‐, high‐salt‐ and cold‐responsive gene expression

<jats:title>Summary</jats:title> <jats:p> The transcription factors DREBs/CBFs specifically interact with the dehydration‐responsive element/C‐repeat (DRE/CRT) <jats:italic>cis</jats:italic> ‐acting element (core motif: G/ACCGAC) and control the expression of many stress‐inducible genes in <jats:italic>Arabidopsis</jats:italic> . In rice, we isolated five cDNAs for <jats:italic>DREB</jats:italic> homologs: <jats:italic>OsDREB1A</jats:italic> , <jats:italic>OsDREB1B</jats:italic> , <jats:italic>OsDREB1C</jats:italic> , <jats:italic>OsDREB1D</jats:italic> , and <jats:italic>OsDREB2A</jats:italic> . Expression of <jats:italic>OsDREB1A</jats:italic> and <jats:italic>OsDREB1B</jats:italic> was induced by cold, whereas expression of <jats:italic>OsDREB2A</jats:italic> was induced by dehydration and high‐salt stresses. The OsDREB1A and OsDREB2A proteins specifically bound to DRE and activated the transcription of the <jats:italic>GUS</jats:italic> reporter gene driven by DRE in rice protoplasts. Over‐expression of OsDREB1A in transgenic <jats:italic>Arabidopsis</jats:italic> induced over‐expression of target stress‐inducible genes of <jats:italic>Arabidopsis</jats:italic> DREB1A resulting in plants with higher tolerance to drought, high‐salt, and freezing stresses. This indicated that OsDREB1A has functional similarity to DREB1A. However, in microarray and RNA blot analyses, some stress‐inducible target genes of the DREB1A proteins that have only ACCGAC as DRE were not over‐expressed in the OsDREB1A transgenic <jats:italic>Arabidopsis</jats:italic> . The OsDREB1A protein bound to GCCGAC more preferentially than to ACCGAC whereas the DREB1A proteins bound to both GCCGAC and ACCGAC efficiently. The structures of DREB1‐type ERF/AP2 domains in monocots are closely related to each other as compared with that in the dicots. <jats:italic>OsDREB1A</jats:italic> is potentially useful for producing transgenic monocots that are tolerant to drought, high‐salt, and/or cold stresses. </jats:p>