Aphid effector Mp10 balances immune suppression and defence activation through EDS1-dependent modulation of plant DAMP responses

SUMMARY Damage-associated molecular pattern (DAMP)-triggered immunity (DTI) serves as a crucial first line of defence against aphid attack, yet the mechanisms by which aphids suppress this response remain 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 BAK1/BKK1, CPK5/CPK6, GRP3, and EDS1 collectively contribute to DTI limiting aphid colonisation. We found that aphids limit OG production during feeding. 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 but restoring OG responsiveness under attack, revealing its broader role in immune modulation and effector-driven host adaptation.