Identification and characterization of the novel gene GhDBP2 encoding a DRE-binding protein from cotton (Gossypium hirsutum)

A cDNA encoding one novel DRE-binding protein, GhDBP2, was isolated from cotton seedlings. It is classified into the A-6 group of DREB subfamily based on multiple sequence alignment and phylogenetic characterization. Using semi-quantitative RT-PCR, we found that the GhDBP2 transcripts were greatly induced by drought, NaCl, low temperature and ABA treatments in cotton cotyledons. The DNA-binding properties of GhDBP2 were analyzed by electrophoretic mobility shift assay (EMSA), showing that GhDBP2 successfully binds to the previously characterized DRE cis-element as well as the promoter region of the LEA D113 gene. Consistent with its role as a DNA-binding protein, GhDBP2 is preferentially localized to the nucleus of onion epidermal cells. In addition, when GhDBP2 is transiently expressed in tobacco cells, it activates reporter gene expression driven by the LEA D113 promoter. Taken together, our results indicate that GhDBP2 is a DRE-binding transcriptional activator involved in activation of down-stream genes such as LEA D113 expression through interaction with the DRE element, in response to environmental stresses as well as ABA treatment.