Ustilaginoidea virens secreted effector Uv1809 suppresses rice immunity via OsSRT2-mediated histone acetylation.

Rice false smut caused by Ustilaginoidea virens, is one of the most devastating diseases of rice worldwide. However, the molecular mechanisms of U. virens-rice interaction remain largely unknown. In this study, we identified a secreted protein Uv1809 as a key virulence factor. Heterologous overexpression of Uv1809 in rice enhanced susceptibility to rice pathogens, while host-induced gene silencing (HIGS) of Uv1809 in rice enhanced resistance to U. virens, showed that Uv1809 inhibits rice immunity and then promotes the infection of U. virens. Uv1809 suppresses rice immunity by targeting and enhancing rice histone deacetylase OsSRT2-modulated histone deacetylation, thereby reducing the levels of H4K5ac and H4K8ac and interfering with the activation of defense gene transcription. More importantly, CRISPR-Cas9 editing ossrt2 mutants showed no adverse effects in terms of growth and yield, but it has broad-spectrum resistance to rice pathogens, which can be used as a valuable source of disease resistance breeding.Taken together, our study provided insight into counter-defense mechanism in a plant pathogen that inactivates plant immunity at the epigenetic level.