Cereal Cyst Nematode Effector HfVAP2 Targets and Stabilizes TaCAT3-A1 to Suppress Immune Responses for Parasitism in Wheat

The cereal cyst nematode Heterodera filipjevi secretes effectors into plant cells to promote infection. This study identified two venom allergen-like proteins, HfVAP1 and HfVAP2, which contain secretory signal peptides and are specifically expressed in subventral gland cells. These two proteins inhibit programmed cell death in Nicotiana benthamiana and interact with TaCAT3-A1, a key hydrogen peroxide-scavenging catalase in wheat. Notably, HfVAP2 stabilized TaCAT3-A1 and enhanced its enzymatic activity. Knockout of TaCAT3-A1 in wheat led to increased accumulation of reactive oxygen species (ROS), upregulation of pathogen-related (PR) genes, and suppression of the jasmonic acid (JA) signal pathway, resulting in enhanced resistance to H. filipjevi. Our findings reveal that H. filipjevi secretes HfVAP2 to stabilize TaCAT3-A1, thereby suppressing ROS accumulation and PRs expression, while activating the JA signal pathway to facilitate nematode infection. This study provides new insights into the molecular strategies employed by cereal cyst nematodes (CCNs) to manipulate host immunity.