Fusarium pseudograminearum Effector FpSP5 Is Recognized as a PAMP and Also Contributes to Virulence during Infection.

Fusarium pseudograminearum, the dominant causal agent of Fusarium crown rot (FCR), secretes numerous effectors to modulate host immunity during infection, but the functions of most remain unknown. In this study, we identified FpSP5, an effector from F. pseudograminearum, as a pathogen-associated molecular pattern (PAMP) that triggers plant immunity. FpSP5 induces cell death, oxidative burst, and PTI in Nicotiana benthamiana, conferring resistance against multiple pathogens. Furthermore, its perception specifically depends on the coreceptor BAK1 in N. benthamiana. Interestingly, FpSP5 is not only conserved among fungi and capable of activating defense responses in different plants but also essential for the full virulence of F. pseudograminearum on wheat. Collectively, these findings enhance our understanding of how F. pseudograminearum effectors modulate host immunity and contribute to pathogenicity, laying a foundation for developing targeted strategies to control FCR.