Functional analysis of BpDREB2 gene involved in salt and drought response from a woody plant Broussonetia papyrifera

The dehydration-responsive element binding proteins (DREBs) are important transcription factors in the regulation of plant responses to abiotic stresses. In this study, BpDREB2, an AP2/DREB-type transcription factor gene, was cloned from a woody plant, Broussonetia papyrifera by RACE-PCR. Sequence analyses revealed that BpDREB2 protein has three characteristic domains, including an AP2/EREBP, a nuclear localization signal and an acidic activation domain. Yeast one-hybrid assays showed that BpDREB2 protein specifically binds to the DRE sequence and activates the expression of reporter genes in yeast. These results suggested that BpDREB2 protein could function as a transcription factor of DREB family. The expression of BpDREB2 gene was remarkably induced by dehydration and high-salt treatments, but no significant change was observed under ABA or low-temperature conditions. Importantly, transgenic expression of BpDREB2 gene in Arabidopsis significantly enhanced its tolerance to salt and freezing without causing growth retardation. Taken together, these results suggested that BpDREB2 is a novel member of the AP2/EREBP trans-acting factor family which could enhance salt stress tolerance of plants and has the potential application in the improvement of crops and economical tree species.