title: NPR1 modulates cross-talk between salicylate- and jasmonate-dependent defense pathways through a novel function in the cytosol.
abstract: Plant defenses against pathogens and insects are regulated differentially by cross-communicating signal transduction pathways in which salicylic acid (SA) and jasmonic acid (JA) play key roles. In this study, we investigated the molecular mechanism of the antagonistic effect of SA on JA signaling. Arabidopsis plants unable to accumulate SA produced 25-fold higher levels of JA and showed enhanced expression of the JA-responsive genes LOX2, PDF1.2, and VSP in response to infection by Pseudomonas syringae pv tomato DC3000, indicating that in wild-type plants, pathogen-induced SA accumulation is associated with the suppression of JA signaling. Analysis of the Arabidopsis mutant npr1, which is impaired in SA signal transduction, revealed that the antagonistic effect of SA on JA signaling requires the regulatory protein NPR1. Nuclear localization of NPR1, which is essential for SA-mediated defense gene expression, is not required for the suppression of JA signaling, indicating that cross-talk between SA and JA is modulated through a novel function of NPR1 in the cytosol.
authors.affiliation: Graduate School of Experimental Plant Sciences, Section of Phytopathology, Faculty of Biology, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Spoel
authors.forename: Annemart
authors.initials: A
authors.lastname: Koornneef
authors.forename: Susanne M C
authors.initials: SM
authors.lastname: Claessens
authors.forename: Jerôme P
authors.initials: JP
authors.lastname: Korzelius
authors.forename: Johan A
authors.initials: JA
authors.lastname: Van Pelt
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Mueller
authors.forename: Antony J
authors.initials: AJ
authors.lastname: Buchala
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Métraux
authors.forename: Rebecca
authors.initials: R
authors.lastname: Brown
authors.forename: Kemal
authors.initials: K
authors.lastname: Kazan
authors.forename: L C
authors.initials: LC
authors.lastname: Van Loon
authors.forename: Xinnian
authors.initials: X
authors.lastname: Dong
authors.forename: Corné M J
authors.initials: CM
authors.lastname: Pieterse
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D003517:Cyclopentanes / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D023082:Defensins; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D054883:Oxylipins; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011549:Pseudomonas / Q000254:growth & development; D020156:Salicylic Acid / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C489413:AHBP-1b protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D003517:Cyclopentanes; D004268:DNA-Binding Proteins; D023082:Defensins; C105496:NPR1 protein, Arabidopsis; D009687:Nuclear Proteins; D054883:Oxylipins; D010940:Plant Proteins; D014157:Transcription Factors; C068757:HBP-1b protein, plant; C011006:jasmonic acid; D008084:Lipoxygenase; D020156:Salicylic Acid