The Meloidogyne graminicola effector MgMO289 targets a novel rice copper metallochaperone to suppress plant immunity.

Recent studies have reported that plant-parasitic nematodes facilitate their infection by suppressing plant immunity via effectors, but the inhibitory mechanisms remain poorly understood. This study found that a novel effector MgMO289 is exclusively expressed in the dorsal esophageal gland of Meloidogyne graminicola and is up-regulated at parasitic third-/fourth-stage juveniles. In planta silencing of MgMO289 substantially increased plant resistance to M. graminicola. Further studies found that MgMO289 interacts with a new rice Cu metallochaperone OsHPP04, and the rice cCu/Zn-SOD2 is the target of OsHPP04. OsHPP04- and MgMO289-transgenic rice both exhibited an increased susceptibility to M. graminicola and a higher Cu/Zn-SOD activity, but lower O2 •- content, when compared to wild-type rice. Meanwhile, immune assays showed that MgMO289 can suppress host innate immunity. These findings reveal a novel pathway for a plant pathogen effector that utilize the host O2 •--scavenging system to eliminate O2 •- and suppress plant immunity.