title: Export of salicylic acid from the chloroplast requires the multidrug and toxin extrusion-like transporter EDS5.
abstract: Salicylic acid (SA) is central for the defense of plants to pathogens and abiotic stress. SA is synthesized in chloroplasts from chorismic acid by an isochorismate synthase (ICS1); SA biosynthesis is negatively regulated by autoinhibitory feedback at ICS1. Genetic studies indicated that the multidrug and toxin extrusion transporter ENHANCED DISEASE SUSCEPTIBILITY5 (EDS5) of Arabidopsis (Arabidopsis thaliana) is necessary for SA accumulation after biotic and abiotic stress, but so far it is not understood how EDS5 controls the biosynthesis of SA. Here, we show that EDS5 colocalizes with a marker of the chloroplast envelope and that EDS5 functions as a multidrug and toxin extrusion-like transporter in the export of SA from the chloroplast to the cytoplasm in Arabidopsis, where it controls the innate immune response. The location at the chloroplast envelope supports a model of the effect of EDS5 on SA biosynthesis: in the eds5 mutant, stress-induced SA is trapped in the chloroplast and inhibits its own accumulation by autoinhibitory feedback.
authors.affiliation: Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland.
authors.forename: Mario
authors.initials: M
authors.lastname: Serrano
authors.forename: Bangjun
authors.initials: B
authors.lastname: Wang
authors.forename: Bibek
authors.initials: B
authors.lastname: Aryal
authors.forename: Christophe
authors.initials: C
authors.lastname: Garcion
authors.forename: Eliane
authors.initials: E
authors.lastname: Abou-Mansour
authors.forename: Silvia
authors.initials: S
authors.lastname: Heck
authors.forename: Markus
authors.initials: M
authors.lastname: Geisler
authors.forename: Felix
authors.initials: F
authors.lastname: Mauch
authors.forename: Christiane
authors.initials: C
authors.lastname: Nawrath
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Métraux
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D007113:Immunity, Innate; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009550:Nigericin / Q000494:pharmacology; D030821:Plants, Genetically Modified; D011523:Protoplasts / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; C455514:EDS5 protein, Arabidopsis; D026901:Membrane Transport Proteins; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D020156:Salicylic Acid; D009550:Nigericin