The Fungal Effector Avr-Pita Suppresses Innate Immunity by Increasing COX Activity in Rice Mitochondria
Jingluan Han,
Xiaoyu Wang,
Fengpin Wang,
Zhe Zhao,
Gousi Li,
Xiaoyuan Zhu,
Jing Su,
Letian Chen
Affiliations
Jingluan Han
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University
Xiaoyu Wang
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University
Fengpin Wang
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University
Zhe Zhao
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University
Gousi Li
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University
Xiaoyuan Zhu
Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences
Jing Su
Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences
Letian Chen
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University
Abstract Background Avr-Pita was the first effector identified in the blast fungus (Magnaporthe oryzae)–rice (Oryza sativa) pathosystem. However, the molecular mechanism underlying its effects on the host plant has remained a long-standing mystery. Results Here, we report that ectopically expressing Avr-Pita in rice enhances susceptibility to M. oryzae and suppresses pathogen-associated molecular pattern (PAMP)-triggered defense responses. Avr-Pita targets the host mitochondria and interacts with the cytochrome c oxidase (COX) assembly protein OsCOX11, a key regulator of mitochondrial reactive oxygen species (ROS) metabolism in rice. Overexpressing Avr-Pita or OsCOX11 increased COX activity and decreased ROS accumulation triggered by the fungal PAMP chitin. OsCOX11-overexpressing plants showed increased susceptibility to M. oryzae, whereas OsCOX11-knockdown plants showed resistance to M. oryzae. Conclusions Taken together, these findings suggest that the fungal pathogen M. oryzae delivers the effector Avr-Pita to the host plant, where it enhances COX activity thus decreasing ROS accumulation. Therefore, this effector suppresses host innate immunity by perturbing ROS metabolism in the mitochondria.
