An Effector TaCRVP From Tuta Absoluta Oral Secretion Impairs H 2 O 2 ‐Mediated Plant Defense by Targeting Tomato SlCAT2

ABSTRACT The arms race between plants and herbivorous insects involves sophisticated molecular strategies. While insects commonly secrete salivary effectors to modulate plant defenses, the underlying molecular mechanisms remain poorly characterized. In particular, as a devastating solanaceous pest, how Tuta absoluta , precisely subverts host immunity remains largely unknown. Here, we identify a novel salivary effector, the cysteine‐rich venom protein (TaCRVP), from the oral secretions (OSs) of T. absoluta . We reveal that TaCRVP is translocated into plant cells where it effectively hijacks host redox homeostasis by targeting the tomato catalase SlCAT2. Specifically, TaCRVP not only directly activates SlCAT2 H 2 O 2 ‐scavenging capacity by promoting its tetramerization, but also blocks it from 26S proteasomal degradation by competitively inhibiting its interaction with the host E3 ubiquitin ligase SlAdBiL. Through this sophisticated dual mechanism, TaCRVP enhances SlCAT2 activity and stability to effectively suppress host H 2 O 2 bursts, thereby subverting downstream jasmonic acid (JA) signaling and defensive metabolite production to facilitate insect feeding. Collectively, our results reveal a delicate evolutionary strategy whereby an insect effector hijacks the host SlCAT2‐SlAdBiL regulatory module, contributing to insect adaptation to host plants.