With No‐Lysine Kinase 1 Regulates Biotic and Abiotic Stress Tolerance in Rice by Targeting <scp>OsCATA</scp> to Alter <scp>H</scp> ₂ <scp>O</scp> ₂ Homeostasis

Receptor-like cytoplasmic kinases (RLCKs) play pivotal roles in regulating plant responses to both biotic and abiotic stresses. Although numerous RLCKs have been identified, their underlying regulatory mechanisms remain incompletely understood. In our previous work, we identified the rice OsRLCK109 as a negative regulator of blast resistance. In this study, we aimed to identify interaction partners of OsRLCK109 and to investigate their role in rice responses to both biotic and abiotic stresses. We identified OsWNK1 as an interacting partner of OsRLCK109 and characterised its inhibitory role in regulating rice blast disease, as well as drought and cold stress responses. OsWNK1 directly phosphorylates OsCATA, modulating its enzymatic activity and leading to elevated reactive oxygen species (ROS) levels during pathogen infection. This enhances immune signalling and improves disease resistance. However, under abiotic stress conditions, reduced catalase activity in oswnk1 mutants impairs ROS scavenging, resulting in ROS toxicity and decreased stress tolerance. These findings reveal the dual regulatory role of the OsRLCK109-OsWNK1-OsCATA module in both biotic and abiotic stress responses, thereby offering new insights into a more comprehensive understanding of the stress response mechanism in rice through ROS signalling.