The fungal pathogen Magnaporthe oryzae suppresses innate immunity by modulating a host potassium channel

Potassium (K(+)) is required by plants for growth and development, and also contributes to immunity against pathogens. However, it has not been established whether pathogens modulate host K(+) signaling pathways to enhance virulence and subvert host immunity. Here, we show that the effector protein AvrPiz-t from the rice blast pathogen Magnaporthe oryzae targets a K(+) channel to subvert plant immunity. AvrPiz-t interacts with the rice plasma-membrane-localized K(+) channel protein OsAKT1 and specifically suppresses the OsAKT1-mediated K(+) currents. Genetic and phenotypic analyses show that loss of OsAKT1 leads to decreased K(+) content and reduced resistance against M. oryzae. Strikingly, AvrPiz-t interferes with the association of OsAKT1 with its upstream regulator, the cytoplasmic kinase OsCIPK23, which also plays a positive role in K(+) absorption and resistance to M. oryzae. Furthermore, we show a direct correlation between blast disease resistance and external K(+) status in rice plants. Together, our data present a novel mechanism by which a pathogen suppresses plant host immunity by modulating a host K(+) channel.