WRKY Transcription Factors in Wheat and Their Induction by Biotic and Abiotic Stress
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WRKY proteins constitute a large family of transcription factors in higher plants, and are involved in the regulation of development, senescence and stress resistance. However, little is known with respect to the constitution and function of WRKY genes in bread wheat (Triticum aestivum). We identified a set of 92 wheat WRKY genes from publicly available sequence databases, and constructed a phylogeny map based on the conserved WRKY domain peptide sequences. The wheat sequences were classified into the standard set of WRKY groups and sub-groups established from plant model genomes. Our results show the WRKY orthologues of wheat and rice are more similar compared to their Arabidopsis counterparts. Therefore, we argue some expansion of the WRKY family occurred following the divergence of these three species. The induction of sequence variation in a subset of 18 TaWRKY genes via somatic hybridization was studied by comparing the sequences from cv. JN177 and its derivative cv. SR3. We also analyzed the responses of these 18 genes to imposed salinity, PEG, ABA and SA using quantitative real time PCR. Nine of the 18 TaWRKY genes were up-regulated by exogenous SA. Six genes were up-regulated by salinity or PEG treatment, and their expression was also induced by exogenous ABA. Interestingly, induction by salinity or PEG was impaired when ABA biosynthesis was inhibited. The indication was that most of the TaWRKY genes involved in the abiotic stress response acted in an ABA-dependent manner.
KeywordsAbiotic stress Somatic hybridization Triticum aestivum Variation WRKY domain
C terminus WRKY domain
Expressed sequence tag
N terminus WRKY domain
This work was supported by the funds of the National Basic Research 973 Program of China (2009CB118300 and 2012CB114200), National Transgenic Project (Grants 2011ZX08002-002) and Natural Science Foundation of China (31271707, 31000568 and 31030053). We thank Dr. Austin Cape for careful reading of the manuscript and insightful comments.
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