Transcriptional and post-translational regulation of wheat TaWRKY40 orchestrates ROS-mediated plant resistance against stripe rust fungus

Reactive oxygen species (ROS) generated by respiratory burst oxidase homologs (RBOHs) are critical for plant immunity. Despite the known transcriptional and post-translational regulation of RBOHD activity, the dynamic control of the ROS burst during plant immune responses remains elusive. Here, we demonstrate that upon infection with avirulent Puccinia striiformis f. sp. tritici (Pst) races, the wheat transcription factor TaWRKY40 is activated, driving an extracellular ROS burst by binding to the promoter of TaNOX10 (RBOHD) and transcriptionally activating it. Furthermore, TaWRKY40 undergoes phosphorylation by the brassinolide signaling kinase TaBSK3, which promotes TaWRKY40 nuclear translocation and enhances TaNOX10 transactivation. This cascade elevates extracellular ROS levels, conferring resistance to stripe rust. Conversely, when encountering virulent Pst races, another wheat WRKY transcription factor, TaWRKY19, is upregulated, which transcriptionally suppresses TaWRKY40 and competitively binds to the same cis-element in the TaNOX10 promoter. This jointly inhibits TaNOX10 expression, suppresses ROS accumulation, and renders wheat susceptible. Collectively, 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 ROS regulation by TaWRKY19 and TaWRKY40 enables wheat to mount differential resistance against Pst races with distinct virulence levels.