Abstract
We have reported that Arabidopsis transcription factors DREB1s control expression of abiotic stress-responsive genes. Rice has 10 DREB1/CBF family genes and we isolated cDNAs for these DREB1 homologues, OsDREB1s. Overexpression of OsDREB1A in rice activated expression of target stress-responsive genes such as lip9 and improved stress tolerance to drought, high-salinity and cold. Recently, we reported that 10 OsDREB1 genes were expressed in response to different stresses and proteins encoded by these genes showed different transactivation abilities.
In this study, we analyzed expression of the OsDREB1 genes histochemically using transgenic rice containing a GUS gene regulated under promoters of the OsDREB1 genes, respectively. Under cold condition, blue staining was observed at roots of the OsDREB1C-promoter:GUS plants. We examined whether the OsDREB1s could activate the lip9 promoter by transactivation assay using Arabidopsis protoplasts. OsDREB1C, 1E, 1G and 1I could activate the lip9 promoter like OsDREB1A.
