Aphid effector Mp10 balances immune suppression and defence activation through <scp>EDS1</scp> ‐dependent modulation of plant <scp>DAMP</scp> responses

Damage-associated molecular pattern (DAMP)-triggered immunity (DTI) serves as a crucial first line of defence against aphid attack, yet how aphids manage this response remains unclear. By investigating the colonisation of Arabidopsis thaliana by the highly polyphagous peach-potato aphid (Myzus persicae), we identified cell wall-derived DAMPs, specifically oligogalacturonides (OGs), as key in inducing DTI against aphids. The OG-responsive immune components BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1/BAK1-LIKE 1, CPK5/CPK6, GLYCINE-RICH PROTEIN 3, and EDS1 collectively contribute to DTI limiting aphid colonisation. We found that aphid feeding limits OG production in response to wounding. Additionally, the salivary chemosensory protein (CSP) effector Mp10/CSP4, which is known to be delivered into the cytoplasm of plant cells early in aphid attack, inhibits OG-induced DTI. While Mp10 suppresses OG-induced DTI, it also interacts with EDS1-mediated defences, enhancing aphid fecundity in the absence of EDS1 while restoring OG responsiveness, revealing its broader role in immune modulation and effector-driven host adaptation.