The nematode effector Mj-NEROSs interacts with ISP influencing plastid ROS production to suppress plant immunity

Root-knot nematodes are an important group of plant pathogens that mainly infect plant roots. They establish a feeding site in the host upon infection while secreting hundreds of effectors. These effector proteins are crucial for successful pathogen propagation. Although many effectors have been described, their targets and molecular mode of action are still unknown. Here we report the analysis of the RKN effector, Mj-NEROSs (Meloidogyne javanica nematode effector ROS suppressor), which emerges to have an essential role in suppressing host immunity by inhibiting INF1-induced cell death and reducing callose deposition. Secreted from the subventral esophageal glands to giant cells, Mj-NEROSs localizes in plastids where it interacts with ISP, interfering with the electron transport rate and ROS production. Moreover, our transcriptome analysis shows the downregulation of ROS-related genes upon Mj-NEROSs expression. We propose that Mj-NEROSs manipulates root plastids leading to transcriptional changes, lowering ROS production, and suppressing host immunity. ### Competing Interest Statement The authors have declared no competing interest.