title: Comparative Proteomics Analysis of Phloem Exudates Collected during the Induction of Systemic Acquired Resistance.
abstract: Systemic acquired resistance (SAR) is a plant defense response that provides long-lasting, broad-spectrum pathogen resistance to uninfected systemic leaves following an initial localized infection. In Arabidopsis (Arabidopsis thaliana), local infection with virulent or avirulent strains of Pseudomonas syringae pv tomato generates long-distance SAR signals that travel from locally infected to distant leaves through the phloem to establish SAR In this study, a proteomics approach was used to identify proteins that accumulate in phloem exudates in response to the induction of SAR To accomplish this, phloem exudates collected from mock-inoculated or SAR-induced leaves of wild-type Columbia-0 plants were subjected to label-free quantitative liquid chromatography-tandem mass spectrometry proteomics. Comparing mock- and SAR-induced phloem exudate proteomes, 16 proteins were enriched in phloem exudates collected from SAR-induced plants, while 46 proteins were suppressed. SAR-related proteins THIOREDOXIN h3, ACYL-COENZYME A-BINDING PROTEIN6, and PATHOGENESIS-RELATED1 were enriched in phloem exudates of SAR-induced plants, demonstrating the strength of this approach and suggesting a role for these proteins in the phloem during SAR To identify novel components of SAR, transfer DNA mutants of differentially abundant phloem proteins were assayed for SAR competence. This analysis identified a number of new proteins (m-type thioredoxins, major latex protein-like protein, ULTRAVIOLET-B RESISTANCE8 photoreceptor) that contribute to the SAR response. The Arabidopsis SAR phloem proteome is a valuable resource for understanding SAR long-distance signaling and the dynamic nature of the phloem during plant-pathogen interactions.
authors.affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (P.C., D.C.W., R.K.C.); andResearch Unit Protein Science (J.M.-P., S.M.H.) and Department of Environmental Sciences, Institute of Biochemical Plant Pathology (S.D., A.C.V.), Helmholtz Zentrum Muenchen, Neuherberg, 85764 Munich, Germany.
authors.forename: Philip
authors.identifier: 0000-0002-5467-7290
authors.initials: P
authors.lastname: Carella
authors.affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (P.C., D.C.W., R.K.C.); andResearch Unit Protein Science (J.M.-P., S.M.H.) and Department of Environmental Sciences, Institute of Biochemical Plant Pathology (S.D., A.C.V.), Helmholtz Zentrum Muenchen, Neuherberg, 85764 Munich, Germany.
authors.forename: Juliane
authors.identifier: 0000-0002-3422-4083
authors.initials: J
authors.lastname: Merl-Pham
authors.affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (P.C., D.C.W., R.K.C.); andResearch Unit Protein Science (J.M.-P., S.M.H.) and Department of Environmental Sciences, Institute of Biochemical Plant Pathology (S.D., A.C.V.), Helmholtz Zentrum Muenchen, Neuherberg, 85764 Munich, Germany.
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Wilson
authors.affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (P.C., D.C.W., R.K.C.); andResearch Unit Protein Science (J.M.-P., S.M.H.) and Department of Environmental Sciences, Institute of Biochemical Plant Pathology (S.D., A.C.V.), Helmholtz Zentrum Muenchen, Neuherberg, 85764 Munich, Germany.
authors.forename: Sanjukta
authors.initials: S
authors.lastname: Dey
authors.affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (P.C., D.C.W., R.K.C.); andResearch Unit Protein Science (J.M.-P., S.M.H.) and Department of Environmental Sciences, Institute of Biochemical Plant Pathology (S.D., A.C.V.), Helmholtz Zentrum Muenchen, Neuherberg, 85764 Munich, Germany.
authors.forename: Stefanie M
authors.initials: SM
authors.lastname: Hauck
authors.affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (P.C., D.C.W., R.K.C.); andResearch Unit Protein Science (J.M.-P., S.M.H.) and Department of Environmental Sciences, Institute of Biochemical Plant Pathology (S.D., A.C.V.), Helmholtz Zentrum Muenchen, Neuherberg, 85764 Munich, Germany.
authors.forename: A Corina
authors.initials: AC
authors.lastname: Vlot
authors.affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (P.C., D.C.W., R.K.C.); andResearch Unit Protein Science (J.M.-P., S.M.H.) and Department of Environmental Sciences, Institute of Biochemical Plant Pathology (S.D., A.C.V.), Helmholtz Zentrum Muenchen, Neuherberg, 85764 Munich, Germany rcamero@mcmaster.ca.
authors.forename: Robin K
authors.initials: RK
authors.lastname: Cameron
mesh_terms: D017360:Arabidopsis / Q000276:immunology* / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000378:metabolism*; D063990:Gene Ontology; D007113:Immunity, Innate; D052585:Phloem / Q000378:metabolism*; D010935:Plant Diseases / Q000276:immunology*; D053147:Plant Exudates / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D015203:Reproducibility of Results; D015398:Signal Transduction / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; D053147:Plant Exudates; D020543:Proteome