A Novel Dehydration-Responsive Element-Binding Protein from Caragana korshinskii Is Involved in the Response to Multiple Abiotic Stresses and Enhances Stress Tolerance in Transgenic Tobacco

The dehydration-responsive element-binding (DREB) protein specifically binds the dehydration-responsive element and is part of a plant-specific family of transcription factors that play important roles in regulating the expression of genes in response to a variety of abiotic stresses, including drought, high salt, and low temperature. In this study, a DREB-like gene containing a conserved APETLA2 (AP2)/ethylene responsive element binding factor (ERF) domain, termed DRE binding factor (CkDBF), was isolated from Caragana korshinskii. The K, R-rich motif in the N-terminal region was shown to play an essential role in nuclear localization of CkDBF. DNA-binding specificity and transactivation activity of CkDBF were verified by yeast one-hybrid experiments. Expression of CkDBF was shown to be upregulated by high salt, dehydration, low temperature, and the phytohormone abscisic acid (ABA). Overexpression of CkDBF in transgenic tobacco plants resulted in higher tolerance to high salinity and osmotic stresses and induction of a downstream target gene under normal conditions. These results suggest that CkDBF may play an essential role as a DREB transcription factor in regulation of stress-responsive signaling in C. korshinskii.