The Fungal Effector Avr-Pita Suppresses Innate Immunity by Increasing COX Activity in Rice Mitochondria

• Published in: Rice (New York, N.Y.) Vol. 14; no. 1; p. 12
• Main Authors: Han, Jingluan, Wang, Xiaoyu, Wang, Fengpin, Zhao, Zhe, Li, Gousi, Zhu, Xiaoyuan, Su, Jing, Chen, Letian
• Format: Journal Article
• Language: English
• Published: New York Springer US 14-01-2021; Springer Nature B.V; SpringerOpen
• Subjects: Accumulation; Agriculture; Avr-Pita; Biomedical and Life Sciences; Chitin; Cytochrome c oxidase (COX); Cytochrome-c oxidase; Cytochromes; Effector; Fungi; Host plants; Immunity; Innate immunity; Life Sciences; Metabolism; Mitochondria; Mitochondrion; Next Generation Rice Disease Research; Original; Original Article; Pathogens; Plant Breeding/Biotechnology; Plant Ecology; Plant Genetics and Genomics; Plant Sciences; Reactive oxygen species; Reactive oxygen species (ROS); Rice; Rice blast; Mitochondrion; Cytochrome; Avr-Pita; Reactive oxygen species (ROS); Innate immunity; Effector; oxidase (COX); Cytochrome c oxidase (COX)
• ISSN: 1939-8425; 1939-8433; 1934-8037
• DOI: 10.1186/s12284-021-00453-4

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.