An Ustilaginoidea virens Nuclear Effector SCRE7 Inhibits Rice Immunity via Suppressing OsLBD11/12-Promoted Transcription of OsCPS2.

Phytopathogenic fungi secrete a great number of effector proteins into various organelles of host plants and suppress plant immunity through different mechanisms. In this study, we identify SCRE7 as a unique nuclear effector that is essential for U. virens infection. SCRE7 interacts with a transcription factor OsLBD11/12 in rice nuclei. Interestingly, defence responses and rice resistance against bacterial and fungal diseases are negatively modulated by SCRE7, but positively regulated by OsLBD11/12. Consistently, transcriptome analyses revealed that SCRE7 and OsLBD11/12 oppositely regulate multiple immune-related pathways in rice. Furthermore, we demonstrated that OsLBD11/12 activates the transcription of OsCPS2 encoding a positive immune regulator through specifically binding to the cis-element in the OsCPS2 promoter. SCRE7 attenuates the binding of OsLBD11/12 to the cis-element and thereby inhibits the transcriptional activity of the transcription factor and rice immunity. The findings not only represent an unidentified infection strategy in U. virens, but also provide candidate gene targets for the creation of disease-resistant germplasms in rice.