A Group I WRKY Gene, TaWRKY133, Negatively Regulates Drought Resistance in Transgenic Plants

Abstract

WRKYs are one of the largest transcription factor (TF) families and play an important role in plant resistance to various stresses. TaWRKY133, a group I WRKY protein, responds to a variety of abiotic stresses, including PEG treatment. The TaWRKY133 protein is located in the nucleus of tobacco epidermal cells, and both its N-terminal and C-terminal domains exhibit transcriptional activation activity. Overexpression of <i>TaWRKY133</i> reduced drought tolerance in <i>Arabidopsis thaliana</i>, as reflected by a lower germination rate, shorter roots, higher stomatal aperture, poorer growth and lower antioxidant enzyme activities under drought treatment. Moreover, expression levels of stress-related genes (<i>DREB2A</i>, <i>RD29A</i>, <i>RD29B</i>, <i>ABF1</i>, <i>ABA2</i>, <i>ABI1</i>, <i>SOD (Cu/Zn)</i>, <i>POD1</i> and <i>CAT1</i>) were downregulated in transgenic <i>Arabidopsis</i> under drought stress. Gene silencing of <i>TaWRKY133</i> enhanced the drought tolerance of wheat, as reflected in better growth, higher antioxidant enzyme activities, and higher expression levels of stress-related genes including <i>DREB1</i>, <i>DREB3</i>, <i>ABF</i>, <i>ERF3</i>, <i>SOD (Fe)</i>, <i>POD</i>, <i>CAT</i> and <i>P5CS</i>. In conclusion, these results suggest that <i>TaWRKY133</i> might reduce drought tolerance in plants by regulating the expression of stress-related genes.