title: Plasma Membrane Microdomains Are Essential for Rac1-RbohB/H-Mediated Immunity in Rice.
abstract: Numerous plant defense-related proteins are thought to congregate in plasma membrane microdomains, which consist mainly of sphingolipids and sterols. However, the extent to which microdomains contribute to defense responses in plants is unclear. To elucidate the relationship between microdomains and innate immunity in rice (Oryza sativa), we established lines in which the levels of sphingolipids containing 2-hydroxy fatty acids were decreased by knocking down two genes encoding fatty acid 2-hydroxylases (FAH1 and FAH2) and demonstrated that microdomains were less abundant in these lines. By testing these lines in a pathogen infection assay, we revealed that microdomains play an important role in the resistance to rice blast fungus infection. To illuminate the mechanism by which microdomains regulate immunity, we evaluated changes in protein composition, revealing that microdomains are required for the dynamics of the Rac/ROP small GTPase Rac1 and respiratory burst oxidase homologs (Rbohs) in response to chitin elicitor. Furthermore, FAHs are essential for the production of reactive oxygen species (ROS) after chitin treatment. Together with the observation that RbohB, a defense-related NADPH oxidase that interacts with Rac1, is localized in microdomains, our data indicate that microdomains are required for chitin-induced immunity through ROS signaling mediated by the Rac1-RbohB pathway.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakuraku, Saitama 338-8570, Japan mnagano@mail.saitama-u.ac.jp.
authors.forename: Minoru
authors.initials: M
authors.lastname: Nagano
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakuraku, Saitama 338-8570, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan Institute for Advanced Biosciences, Keio University, 246-2 Mizukami, Kakuganji, Tsuruoka, Yamagata 997-0052, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Fujiwara
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan Department of Bioinformatics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Fukao
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan Shanghai Center for Plant Stress Biology, Shanghai 201602, P.R. China.
authors.forename: Yoji
authors.initials: Y
authors.lastname: Kawano
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakuraku, Saitama 338-8570, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Kawai-Yamada
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Ko
authors.initials: K
authors.lastname: Shimamoto
mesh_terms: D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D021962:Membrane Microdomains / Q000235:genetics* / Q000378:metabolism*; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D057865:Plant Immunity / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
chemical_list: D010940:Plant Proteins; D017382:Reactive Oxygen Species