title: Regulation of Stomatal Immunity by Interdependent Functions of a Pathogen-Responsive MPK3/MPK6 Cascade and Abscisic Acid.
abstract: Activation of mitogen-activated protein kinases (MAPKs) is one of the earliest responses after plants sense an invading pathogen. Here, we show that MPK3 and MPK6, twoArabidopsis thalianapathogen-responsive MAPKs, and their upstream MAPK kinases, MKK4 and MKK5, are essential to both stomatal and apoplastic immunity. Loss of function ofMPK3andMPK6, or their upstreamMKK4andMKK5, abolishes pathogen/microbe-associated molecular pattern- and pathogen-induced stomatal closure. Gain-of-function activation of MPK3/MPK6 induces stomatal closure independently of abscisic acid (ABA) biosynthesis and signaling. In contrast, exogenously applied organic acids such as malate or citrate are able to reverse the stomatal closure induced by MPK3/MPK6 activation. Gene expression analysis and in situ enzyme activity staining revealed that malate metabolism increases in guard cells after activation of MPK3/MPK6 or inoculation of pathogen. In addition, pathogen-induced malate metabolism requires functional MKK4/MKK5 and MPK3/MPK6. We propose that the pathogen-responsive MPK3/MPK6 cascade and ABA are two essential signaling pathways that control, respectively, the organic acid metabolism and ion channels, two main branches of osmotic regulation in guard cells that function interdependently to control stomatal opening/closure.
authors.affiliation: Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.|Division of Biochemistry, Interdisciplinary Plant Group, Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211.
authors.forename: Jianbin
authors.identifier: http://orcid.org/0000-0002-1201-0076
authors.initials: J
authors.lastname: Su
authors.affiliation: Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
authors.forename: Mengmeng
authors.identifier: http://orcid.org/0000-0003-3207-498X
authors.initials: M
authors.lastname: Zhang
authors.affiliation: David H. Hickman High School, Columbia, Missouri 65203.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
authors.forename: Tiefeng
authors.initials: T
authors.lastname: Sun
authors.affiliation: Division of Biochemistry, Interdisciplinary Plant Group, Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211.
authors.forename: Yidong
authors.identifier: http://orcid.org/0000-0002-3401-7893
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Plant Biology, University of Georgia, Athens, Georgia 30602.
authors.forename: Wolfgang
authors.identifier: http://orcid.org/0000-0002-5864-7240
authors.initials: W
authors.lastname: Lukowitz
authors.affiliation: Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China xujuan@zju.edu.cn zhangsh@missouri.edu.
authors.forename: Juan
authors.identifier: http://orcid.org/0000-0001-6683-6415
authors.initials: J
authors.lastname: Xu
authors.affiliation: Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China xujuan@zju.edu.cn zhangsh@missouri.edu.|Division of Biochemistry, Interdisciplinary Plant Group, Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211.
authors.forename: Shuqun
authors.identifier: http://orcid.org/0000-0003-2959-6461
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D054046:Plant Stomata / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D000040:Abscisic Acid; C458516:AtMPK3 protein, Arabidopsis; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; C519871:MKK4 protein, Arabidopsis; C519872:MKK5 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases