title: Cytokinin-Mediated Regulation of Reactive Oxygen Species Homeostasis Modulates Stomatal Immunity in Arabidopsis.
abstract: Stomata play an important role in preinvasive defense responses by limiting pathogen entry into leaves. Although the stress hormones salicylic acid (SA) and abscisic acid (ABA) are known to regulate stomatal immunity, the role of growth promoting hormones is far from understood. Here, we show that inArabidopsis thaliana, cytokinins (CKs) function in stomatal defense responses. The cytokinin receptor HISTIDINE KINASE3 (AHK3) and RESPONSE REGULATOR2 (ARR2) promote stomatal closure triggered by pathogen-associated molecular pattern (PAMP) and resistance toPseudomonas syringaepvtomatobacteria. Importantly, the cytokinintrans-zeatin induces stomatal closure and accumulation of reactive oxygen species (ROS) in guard cells through AHK3 and ARR2 in an SA-dependent and ABA-independent manner. Using pharmacological and reverse genetics approaches, we found that CK-mediated stomatal responses involve the apoplastic peroxidases PRX4, PRX33, PRX34, and PRX71, but not the NADPH oxidases RBOHD and RBOHF. Moreover, ARR2 directly activates the expression of PRX33 and PRX34, which are required for SA- and PAMP-triggered ROS production. Thus, the CK signaling pathway regulates ROS homeostasis in guard cells, which leads to enhanced stomatal immunity and plant resistance to bacteria.
authors.affiliation: Department of Life Sciences, POSTECH Biotech Center, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Dominique
authors.identifier: http://orcid.org/0000-0003-4898-1656
authors.initials: D
authors.lastname: Arnaud
authors.affiliation: School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Seungchul
authors.identifier: http://orcid.org/0000-0003-2801-9670
authors.initials: S
authors.lastname: Lee
authors.affiliation: RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan.
authors.forename: Yumiko
authors.identifier: http://orcid.org/0000-0003-4207-297X
authors.initials: Y
authors.lastname: Takebayashi
authors.affiliation: School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Daeseok
authors.identifier: http://orcid.org/0000-0002-4047-3828
authors.initials: D
authors.lastname: Choi
authors.affiliation: Department of Life Sciences, POSTECH Biotech Center, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Jaemyung
authors.initials: J
authors.lastname: Choi
authors.affiliation: RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama 230-0045, Japan.
authors.forename: Hitoshi
authors.identifier: http://orcid.org/0000-0001-5449-6492
authors.initials: H
authors.lastname: Sakakibara
authors.affiliation: Department of Life Sciences, POSTECH Biotech Center, Pohang University of Science and Technology, Pohang 790-784, Korea ihwang@postech.ac.kr.
authors.forename: Ildoo
authors.identifier: http://orcid.org/0000-0002-9454-3326
authors.initials: I
authors.lastname: Hwang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000071677:Histidine Kinase / Q000235:genetics / Q000378:metabolism; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D000069452:Pathogen-Associated Molecular Pattern Molecules / Q000378:metabolism; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism; D054046:Plant Stomata / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D044224:Pseudomonas syringae / Q000472:pathogenicity; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D003583:Cytokinins; D004268:DNA-Binding Proteins; D000071677:Histidine Kinase; D019255:NADPH Oxidases; D000069452:Pathogen-Associated Molecular Pattern Molecules; D010544:Peroxidases; D017382:Reactive Oxygen Species; D020156:Salicylic Acid; D014157:Transcription Factors; C117139:ARR2 protein, Arabidopsis; C000597916:Prx71 protein, Arabidopsis; C000605117:peroxidase 4, Arabidopsis; C574008:PRX33 protein, Arabidopsis; C553803:PRX34 protein, Arabidopsis; C568857:AT5G47910 protein, Arabidopsis; C000589475:RBOH F protein, Arabidopsis; C000605493:AHK3 protein, Arabidopsis