Characterization of OsDREB6 responsive to osmotic and cold stresses in rice

We identified a new dehydration-responsive element-binding protein gene, OsDREB6, which is an A-6 subgroup member of the DREB subfamily, of AP2/EREBP proteins, in Oryza sativa ssp. Japonica cv. Nipponbare. Expression pattern analysis indicated that OsDREB6 was induced in response to dehydration, high salinity, and most importantly by cold stress (4°C). Analysis using the yeast one-hybrid system showed that OsDREB6 had transcriptional activation activity and bound specifically to the DRE ciselement. Overexpression of OsDREB6 increased tolerance to osmotic, high salt, and cold stresses in transgenic rice whereas, OsDREB6 double-stranded RNA interference (RNAi) lines were found to be more sensitive to these stresses than wild-type rice. Additionally, sugar, proline and catalase levels in OsDREB6 RNAi lines were significantly lower than in the corresponding OsDREB6 overexpression lines and control lines after PEG treatment. In contrast, malondialdehyde (MDA) levels were significantly higher in RNAi lines than in control and overexpression lines. Furthermore, expression levels of some stress-related genes were altered in the transgenic plants. The data suggests that OsDREB6 may participate in the stress response by mediating the expression of specific genes, and may also be involved plant metabolism. Together, these results indicated that OsDREB6 plays an important role in the response of plants to a wide range of osmotic stresses.