The Cytosolic Iron-Sulfur Cluster Assembly Targeting Complex Is Hijacked by Magnaporthe Effector AvrPi9 to Suppress Rice Resistance.

The cytosolic iron-sulfur (Fe-S) cluster assembly (CIA) targeting complex mediates the maturation of cytosolic and nuclear Fe-S proteins and governs core eukaryotic cellular processes. However, whether this complex contributes to plant disease resistance remains unclear. Here, we show that the Magnaporthe oryzae avirulence effector AvrPi9 targets the host CIA targeting complex to suppress rice blast resistance. AvrPi9 physically interacts with and stabilizes OsAE7, a core subunit of the CIA targeting complex. Using biochemical and genetic approaches, we demonstrate that OsAE7 facilitates Fe-S protein maturation, including the Fe-S protein aconitase OsACO1, and negatively regulates blast resistance in cooperation with another CIA targeting complex subunit, OsCIA1, and the carrier protein OsNAR1 in rice. Furthermore, ectopic expression of AvrPi9 enhances the activity of the CIA complex and the maturation of OsACO1. Knockout of OsACO1 elevates ferrous iron levels, triggers a reactive oxygen species (ROS) burst, and activates pathogenesis-related gene transcription, thereby strengthening rice resistance to blast. Our findings reveal a critical role of the CIA targeting complex in plant disease resistance and uncover a novel virulence strategy whereby AvrPi9 hijacks the host CIA pathway to dampen basal resistance and promote infection.