A Valsa mali Effector Protein 1 Targets Apple (Malus domestica) Pathogenesis-Related 10 Protein to Promote Virulence

Abstract

To successfully colonize the plants, the pathogenic microbes secrete a mass of effector proteins which manipulate host immunity. Apple valsa canker is a destructive disease caused by the weakly parasitic fungus Valsa mali . A previous study indicated that the V. mali effector protein 1 ( VmEP1 ) is an essential virulence factor. However, the pathogenic mechanism of VmEP1 in V . mali remains poorly understood. In this study, we found that the apple ( Malus domestica ) pathogenesis-related 10 proteins ( MdPR10 ) are the virulence target of VmEP1 using a yeast two-hybrid screening. By bimolecular fluorescence (BiFC) and coimmunoprecipitation (Co-IP), we confirmed that the VmEP1 interacts with MdPR10 in vivo . Silencing of MdPR10 notably enhanced the V . mali infection, and overexpression of MdPR10 markedly reduced its infection, which corroborates its positive role in plant immunity against V . mali . Furthermore, we showed that the co-expression of VmEP1 with MdPR10 compromised the MdPR10 -mediated resistance to V . mali . Taken together, our results revealed a mechanism by which a V . mali effector protein suppresses the host immune responses by interfering with the MdPR10 -mediated resistance to V . mali during the infection.