Transcriptional and post-translational regulation of wheat TaWRKY40 orchestrates ROS-mediated plant resistance...

Reactive oxygen species (ROS) produced by respiratory burst oxidase homologs (RBOHs) are critical for plant immunity. Despite transcriptional and post-translational regulation of RBOHD activity, the dynamic control of the ROS burst during plant immune responses remains unclear. Here, we demonstrate that upon infection with avirulent Puccinia striiformis f. sp. tritici (Pst), the wheat transcription factor TaWRKY40 is activated, driving an extracellular ROS burst by binding to the TaNOX10 (RBOHD) promoter and inducing its activation. Furthermore, TaWRKY40 undergoes phosphorylation by the brassinolide signaling kinase TaBSK3, promoting TaWRKY40 nuclear translocation and enhancing TaNOX10 transactivation. This cascade increases extracellular ROS levels, conferring resistance to stripe rust. When encountering virulent Pst races, another wheat WRKY transcription factor, TaWRKY19, is upregulated, transcriptionally suppressing TaWRKY40 and binding to the same cis element in the TaNOX10 promoter. This inhibits TaNOX10 expression, suppresses ROS accumulation, and renders wheat susceptible. These findings reveal a transcriptional activation module comprising TaBSK3-TaWRKY40-TaNOX10 that governs ROS production and establish a TaWRKY19-TaWRKY40 dual-regulatory module that fine-tunes ROS burst during wheat-Pst interactions. Importantly, this coordinated regulation of ROS by TaWRKY19 and TaWRKY40 enables wheat to have differential resistance against Pst races with diverse virulence levels.