A Novel Secreted Protein of Fusarium oxysporum Promotes Infection by Inhibiting PR‐5 Protein in Plant

ABSTRACT Fusarium oxysporum , an important soilborne fungal pathogen that causes serious Fusarium wilt disease, secretes diverse effectors during the infection. In this study, we identified a novel secreted cysteine‐rich protein, FolSCP1, which contains unknown protein functional domain. Here, we characterized FolSCP1 as a secreted virulence factor that promotes the pathogen infection of host plants by inhibiting diverse plant defence responses. FolSCP1 interacted with the pathogenesis‐related 5 (PR‐5) protein SlPR5, a positive regulator of tomato plant immunity against multiple tomato pathogens, and effectively attenuated the antifungal activity of the tomato PR‐5 protein. FoSCP1, a homologue of FolSCP1, was secreted by a F. oxysporum isolate from infected tobacco and targeted the tobacco PR‐5 protein NtPR5 to suppress plant defence for further infection. In summary, our study revealed a fungal virulence strategy in which F. oxysporum secrete effectors that interfere with plant immunity by binding to the PR‐5 protein of the host plant and inhibiting its biological activity, thereby promoting fungal infection.