Overexpression of the Polygonum cuspidatum PcDREB2A Gene Encoding a DRE-Binding Transcription Factor Enhances the Drought Tolerance of Transgenic Arabidopsis thaliana

Plants have evolved complex signaling networks that enable them to adapt to adverse environmental conditions. The dehydration-responsive element-binding (DREB) transcription factors are important for plant responses to abiotic stresses. In this study, a new member of the AP2/ERF transcription factor gene family, PcDREB2A, was cloned and characterized from Polygonum cuspidatum, a traditional Chinese medicinal herb. PcDREB2A, which includes a typical AP2 domain, was clustered in the A-2 subgroup of the DREB subfamily. At the seedling stage, PcDREB2A expression was induced by cold, salt, and drought stresses. A yeast one-hybrid assay and an analysis of transiently transformed tobacco revealed that PcDREB2A can specifically bind to the DRE motif and transactivate reporter gene expression. Following 200 and 250 mM mannitol treatments, the PcDREB2A-overexpressing Arabidopsis thaliana lines had longer roots and a significantly higher fresh weight than the wild-type plants. Furthermore, under drought stress conditions, the PcDREB2A-overexpressing A. thaliana plants accumulated less malondialdehyde than the control plants. These results indicate that PcDREB2A encodes a novel DREB transcription factor in P. cuspidatum. Furthermore, the data generated in this study may be useful for researchers and breeders interested in genetically engineering plants to increase drought tolerance without inhibiting growth.