Abstract：Transcription factors WRKY are plant specific genes and participate in response to various biotic and abiotic stress. To investigate the role of the WRKY gene in wheat and explore their role in the respons to abiotic stress, in this study, a new wheat(Triticum aestivum L.) WRKY transcription factor, designated as TaWRKY51 was cloned by using RT-PCR, combined with RACE method. The full-length cDNA of TaWRKY51 was of 1 295 bp with a 942 bp of open read frame(ORF) encoding a protein of 313 amino acid residues. Length of 3'UTR and 5'UTR were 73 and 280 bp, respectively. Sequence and structure analysis indicated that TaWRKY51 possessed one WRKY domain and one C2H2 type Zinc-finger domain. BLAST analysis revealed that TaWRKY51 was most homologous to OsWRKY51 from rice(Oryza sativa)(66%), and AtWRKY11, AtWRKY17 from Arabidopsis thaliana(57%). Phylogenetic analysis revealed that all WRKY domain containing proteins could be grouped into three classes and TaWRKY51 belonged to the ClassⅡ because TaWRKY51 contained one WRKY domain and one C2H2 type Zinc-finger domain. Semi-quantitative RT-PCR analysis exhibited that the mRNA abundance of TaWRKY51 was relatively higher in leaves, root and inter-node, as compared to in seeds of 12 d after pollination. The expression level of TaWRKY51 gene was also higher in mature leaves and aged leaves than in young leaves. The results indicated that TaWRKY51 could be a positive regulator in leaves maturing and aging. And expression level of TaWRKY51 gene was upregulated after drought treatment which suggested that TaWRKY51 might be involved in abiotic stress response. Moreover, ecotopic overexpression of TaWRKY51 in A. thaliana significantly increased the number of lateral root, suggesting TaWRKY51 might participate in lateral root regulation in A. thaliana. Remarkably, transgenic lines grown on MS medium containing ABA, mennitol and NaCl were much more sensitive to ABA, drought and salt stress as compared to WT, and transgenic lines grown on soil could not survive after salt and drought stress. These results indicated that TaWRKY51 could be a negative regulator in stress signal transduction pathway. All together, in the present study, we identified a new wheat WRKY gene and analyzed its mRNA expression pattern in different tissues, in leaves at different growing period, and in response to abiotic stress. The results revealed that the gene may play a role in abiotic stress response to environment. These data enable us to better understand the underlying molecular mechanism of TaWRKY51 in plant lateral root development and abiotic stress response.
