TaWRKY70 positively regulates TaCAT5 enhanced Cd tolerance in transgenic Arabidopsis

The WRKY transcription factors (TFs) are involved in plant responses to multiple biotic and abiotic stressors; however, the role of WRKY TFs in the regulation of Cd stress in wheat remains unknown. In this study, we investigated the mechanism of the wheat TaWRKY70 TF in Cd stress. TaWRKY70 expression in Arabidopsis was used for the functional analysis. TaWRKY70 regulated Cd tolerance with Cd accumulating in roots but not in the leaf tissues of transgenic Arabidopsis. The net Cd2+ influx into Arabidopsis roots decreased when TaWRKY70 was expressed. The quantitative real-time-polymerase chain reaction (qRT-PCR) results showed that the expression levels of heavy metal ATPase (AtHMA3), natural resistance-associated macrophage protein (AtNRAMP5), yellow stripe1-like (AtYSL3), and iron transport protein (AtIRT1) decreased under Cd-stress condition. Electrolyte leakage, as well as malondialdehyde and hydrogen peroxide contents, were lower in transgenic Arabidopsis than those in the wild-type (WT), whereas antioxidant enzyme activities were higher. Electrophoretic mobility shift assay (EMSA), yeast one-hybrid (Y1H) assay, and transient transactivation assay confrmed that TaWRKY70 could directly bind to the TaCAT5 promoter. Our findings provide a novel understanding of the WRKY TFs involved in the response to heavy metal stress.