| WRKY transcription factors, which were first identified from sweet potato, are a kind of DNA-binding proteins containing 60 highly conserved amino acid residues, and could recognize the (T)TGAC(C/T) W-box elements. WRKY proteins can regulate the expression of genes that have W-box in their promoter regions, therefore, WRKY proteins play significant roles in plant growth and development, metabolic regulation, defense and responses to abiotic stresses. Up to now, only a few research has been reported on the cloning and functional analysis of WRKY in wheat, In this study, through searching the wheat EST database by the highly conserved WRKY domain, we identified a total of 23 WRKY unigenes, designed TaWRKY1 to TaWRKY23. The ORF sequence of TaWRKY1 was successfully cloned by using RT-PCR method, and its encoded protein structure was analyzed with various softwares. TaWRKY1 contains a WRKY domain and a zinc-finger motif,which is probably in subgroup IIc of group II. Semi-quantitive RT-PCR was used with a pair of specific primers designed according to the 3'-UTR sequence to analyze the tissue-specific expression of TaWRKY1, and its expression changes in response to low temperature, NaCl and PEG treatment. The results showed that, TaWRKY1 was strongly expressed in leaf, moderately in stem and weakly in root. The expression of TaWRKY1 was greatly enhanced after one hour of cold stress at 4℃, and returned to the normal level thereafter, while no expression changes was observed under NaCl and PEG treatment, indicating that TaWRKY1 is an important specific signaling component of wheat in response to the cold stress. These results of the present study should help to clarify the regulation mechanisms and biological functions of WRKY proteins, and provide valuable reference for cloning novel genes from wheat and other species with complex genome organization. The thus cloned might be a candidate to be used for improving the cold stress resistance of wheat. |
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