title: Magnaporthe oryzae Effector AVR-Pii Helps to Establish Compatibility by Inhibition of the Rice NADP-Malic Enzyme Resulting in Disruption of Oxidative Burst and Host Innate Immunity.
abstract: Plant disease resistance occurs as a hypersensitive response (HR) at the site of attempted pathogen invasion. This specific event is initiated in response to recognition of pathogen-associated molecular pattern (PAMP) and subsequent PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI). Both PTI and ETI mechanisms are tightly connected with reactive oxygen species (ROS) production and disease resistance that involves distinct biphasic ROS production as one of its pivotal plant immune responses. This unique oxidative burst is strongly dependent on the resistant cultivars because a monophasic ROS burst is a hallmark of the susceptible cultivars. However, the cause of the differential ROS burst remains unknown. In the study here, we revealed the plausible underlying mechanism of the differential ROS burst through functional understanding of the Magnaporthe oryzae (M. oryzae) AVR effector, AVR-Pii. We performed yeast two-hybrid (Y2H) screening using AVR-Pii as bait and isolated rice NADP-malic enzyme2 (Os-NADP-ME2) as the rice target protein. To our surprise, deletion of the rice Os-NADP-ME2 gene in a resistant rice cultivar disrupted innate immunity against the rice blast fungus. Malic enzyme activity and inhibition studies demonstrated that AVR-Pii proteins specifically inhibit in vitro NADP-ME activity. Overall, we demonstrate that rice blast fungus, M. oryzae attenuates the host ROS burst via AVR-Pii-mediated inhibition of Os-NADP-ME2, which is indispensable in ROS metabolism for the innate immunity of rice. This characterization of the regulation of the host oxidative burst will help to elucidate how the products of AVR genes function associated with virulence of the pathogen.
authors.affiliation: Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Raksha
authors.initials: R
authors.lastname: Singh
authors.affiliation: Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Sarmina
authors.initials: S
authors.lastname: Dangol
authors.affiliation: Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Yafei
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Jihyun
authors.initials: J
authors.lastname: Choi
authors.affiliation: Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Yoon-Seong
authors.initials: YS
authors.lastname: Cho
authors.affiliation: Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Jea-Eun
authors.initials: JE
authors.lastname: Lee
authors.affiliation: Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Mi-Ok
authors.initials: MO
authors.lastname: Choi
authors.affiliation: Division of Integrative Bioscience and Biotechnology, College of Life Sciences, Sejong University, Seoul 143-747, Korea.
authors.forename: Nam-Soo
authors.initials: NS
authors.lastname: Jwa
mesh_terms: D060467:Disease Resistance; D005656:Fungal Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D007113:Immunity, Innate; D020082:Magnaporthe / Q000276:immunology / Q000378:metabolism* / Q000472:pathogenicity; D008291:Malate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D012275:Oryza / Q000201:enzymology* / Q000382:microbiology; D010935:Plant Diseases / Q000276:immunology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)
keywords: AVR-effectors; NADP-Malic enzyme; gene-for-gene interaction; reactive oxygen species; rice