title: 9-Lipoxygenase-Derived Oxylipins Activate Brassinosteroid Signaling to Promote Cell Wall-Based Defense and Limit Pathogen Infection.
abstract: The oxylipins, a large family of oxygenated lipid derivatives, regulate plant development and immunity. Two members of the 9-lipoxygenase (9-LOX) oxylipin pathway, 9-hydroxyoctadecatrienoic acid and 9-ketooctadecatrienoic acid, control root development and plant defense. Studies in Arabidopsis (Arabidopsis thaliana) using a series of 9-hydroxyoctadecatrienoic acid- and 9-ketooctadecatrienoic acid-insensitive nonresponding to oxylipins (noxy) mutants showed the importance of the cell wall as a 9-LOX-induced defense component and the participation of NOXY proteins in signaling cell wall damage. Here, we examined 9-LOX signaling using the mutants lox1lox5, which lacks 9-LOX activity, and noxy2-2, which shows oxylipin insensitivity and mitochondrial dysfunction. Mutants in brassinosteroids (BRs), a class of plant hormones necessary for normal plant growth and the control of cell wall integrity, were also analyzed. Several lines of evidence indicated that 9-LOX-derived oxylipins induce BR synthesis and signaling to activate cell wall-based responses such as callose deposition and that constitutive activation of BR signaling in bri1-EMS-suppressor 1-D (bes1-D) plants enhances this response. We found that constitutive BR signaling in bes1-D and brassinolide-resistant 1-1D (bzr1-1D) mutants conferred resistance to Pseudomonas syringae. bes1-D and bzr1-1D showed increased resistance to Golovinomyces cichoracearum, an obligate biotrophic fungus that penetrates the cell wall for successful infection, whereas susceptibility was enhanced in lox1lox5 and noxy2-2. Our results indicate a sequential action of 9-LOX and BR signaling in activating cell wall-based defense, and this response prevents pathogen infection. These results show interaction between the 9-LOX and BR pathways and help to clarify their role in modulating plant defense.
authors.affiliation: Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.).
authors.forename: Ruth
authors.initials: R
authors.lastname: Marcos
authors.affiliation: Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.).
authors.forename: Yovanny
authors.initials: Y
authors.lastname: Izquierdo
authors.affiliation: Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.).
authors.forename: Tamara
authors.identifier: http://orcid.org/0000-0001-8056-2828
authors.initials: T
authors.lastname: Vellosillo
authors.affiliation: Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.).
authors.forename: Satish
authors.identifier: http://orcid.org/0000-0001-6132-8868
authors.initials: S
authors.lastname: Kulasekaran
authors.affiliation: Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.).
authors.forename: Tomás
authors.initials: T
authors.lastname: Cascón
authors.affiliation: Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.).
authors.forename: Mats
authors.initials: M
authors.lastname: Hamberg
authors.affiliation: Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.) ccastresana@cnb.csic.es.
authors.forename: Carmen
authors.identifier: http://orcid.org/0000-0002-0715-8965
authors.initials: C
authors.lastname: Castresana
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000276:immunology / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D060406:Brassinosteroids / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D010937:Plant Growth Regulators / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000502:physiology; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D054883:Oxylipins; D010937:Plant Growth Regulators; D008084:Lipoxygenase