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Plant Cell. 2016 Aug;28(8):1966-83. doi: 10.1105/tpc.16.00201. Epub 2016 Jul 27.

Plasma Membrane Microdomains Are Essential for Rac1-RbohB/H-Mediated Immunity in Rice.

Author information

1
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.
2
Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakuraku, Saitama 338-8570, Japan.
3
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.
4
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.
5
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.
6
Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.

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.

PMID:
27465023
PMCID:
PMC5006704
DOI:
10.1105/tpc.16.00201
[Indexed for MEDLINE]
Free PMC Article

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