Abstract
We have reported that Arabidopsis transcription factors DREBs control expression of many stress-responsive genes. In rice, we isolated cDNAs for DREB homologues, OsDREBs. Overexpression of OsDREB1A in rice activated expression of target stress-responsive genes and resulted in improved stress tolerance to drought and cold.
In this study we found 10 DREB1/CBF family genes in rice. We observed that 6 OsDREB1 genes were strongly induced by cold but the other 4 genes were not. We examined transactivation abilities of 10 OsDREBs by trangent transactivation assay using Arabidopsis and rice protoplasts. When we used fusion genes with the GAL4 binding domain and ORFs of OsDREB1s, 9 OsDREB1s showed transactivation activity. However, when we used native OsDREB1s as effectors and an rd29A promoter-GUS gene as a reporter, 2 of 9 OsDREB1s did not show transactivation activity. These results indicate that there may be different functions among 10 OsDREB1s although they have similar structure.
