A cotton (Gossypium hirsutum) DRE-binding transcription factor gene, GhDREB, confers enhanced tolerance to drought, high salt, and freezing stresses in transgenic wheat

A cotton (G. hirsutum L.) dehydration responsive element binding protein gene, GhDREB, which encodes a 153 amino acid protein containing a conserved AP2/EREBP domain, was isolated from the cDNA library of cotton cv. Simian 3 by a yeast one-hybrid system. RNA blot analysis showed that the GhDREB gene was induced in cotton seedlings by drought, high salt and cold stresses. An electrophoretic mobility shift assay (EMSA) indicated that the GhDREB protein bound specifically to the DRE core element (A/GCCGAC) in vitro. Two expression vectors containing the GhDREB gene with either of the Ubiqutin or rd29A promoters were constructed and transferred into wheat (Triticum aestivum L.) by bombardment. Fifty-eight Ubi::GhDREB and 17 rd29A::GhDREB T-0 plants of Yangmai (36 plants) and Lumai (39 plants) were identified by PCR analysis, respectively. Southern blot and RT-PCR analyses showed that two or three copies of the GhDREB were integrated into the Yangmai 10 genome and were expressed at the transcriptional level, and three or four copies were integrated into the Lumai 23 genome. Functional analysis indicated that the transgenic plants had improved tolerance to drought, high salt, and freezing stresses through accumulating higher levels of soluble sugar and chlorophyll in leaves after stress treatments. No phenotype differences were observed between transgenic plants and their non-transgenic controls. These results indicated that GhDREB might be useful in improving wheat stress tolerance through genetic engineering.