title: Rhamnolipids elicit defense responses and induce disease resistance against biotrophic, hemibiotrophic, and necrotrophic pathogens that require different signaling pathways in Arabidopsis and highlight a central role for salicylic acid.
abstract: Plant resistance to phytopathogenic microorganisms mainly relies on the activation of an innate immune response usually launched after recognition by the plant cells of microbe-associated molecular patterns. The plant hormones, salicylic acid (SA), jasmonic acid, and ethylene have emerged as key players in the signaling networks involved in plant immunity. Rhamnolipids (RLs) are glycolipids produced by bacteria and are involved in surface motility and biofilm development. Here we report that RLs trigger an immune response in Arabidopsis (Arabidopsis thaliana) characterized by signaling molecules accumulation and defense gene activation. This immune response participates to resistance against the hemibiotrophic bacterium Pseudomonas syringae pv tomato, the biotrophic oomycete Hyaloperonospora arabidopsidis, and the necrotrophic fungus Botrytis cinerea. We show that RL-mediated resistance involves different signaling pathways that depend on the type of pathogen. Ethylene is involved in RL-induced resistance to H. arabidopsidis and to P. syringae pv tomato whereas jasmonic acid is essential for the resistance to B. cinerea. SA participates to the restriction of all pathogens. We also show evidence that SA-dependent plant defenses are potentiated by RLs following challenge by B. cinerea or P. syringae pv tomato. These results highlight a central role for SA in RL-mediated resistance. In addition to the activation of plant defense responses, antimicrobial properties of RLs are thought to participate in the protection against the fungus and the oomycete. Our data highlight the intricate mechanisms involved in plant protection triggered by a new type of molecule that can be perceived by plant cells and that can also act directly onto pathogens.
authors.affiliation: Laboratoire de Stress, Défenses, et Reproduction des Plantes, L'Unité de Recherche Vignes et Vins de Champagne, Equipe d'Accueil 4707, Université de Reims Champagne-Ardenne, F-51687 Reims Cedex 2, France.
authors.forename: Lisa
authors.initials: L
authors.lastname: Sanchez
authors.forename: Barbara
authors.initials: B
authors.lastname: Courteaux
authors.forename: Jane
authors.initials: J
authors.lastname: Hubert
authors.forename: Serge
authors.initials: S
authors.lastname: Kauffmann
authors.forename: Jean-Hugues
authors.initials: JH
authors.lastname: Renault
authors.forename: Christophe
authors.initials: C
authors.lastname: Clément
authors.forename: Fabienne
authors.initials: F
authors.lastname: Baillieul
authors.forename: Stéphan
authors.initials: S
authors.lastname: Dorey
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D020171:Botrytis / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D003517:Cyclopentanes / Q000378:metabolism; D060467:Disease Resistance / Q000276:immunology*; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006017:Glycolipids / Q000494:pharmacology*; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D054883:Oxylipins / Q000378:metabolism; D044742:Peronospora / Q000187:drug effects / Q000502:physiology; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D044224:Pseudomonas syringae / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013171:Spores, Bacterial / Q000187:drug effects / Q000502:physiology; D013172:Spores, Fungal / Q000187:drug effects / Q000502:physiology
chemical_list: D003517:Cyclopentanes; D005030:Ethylenes; D006017:Glycolipids; D054883:Oxylipins; C418382:rhamnolipid; C011006:jasmonic acid; C036216:ethylene; D020156:Salicylic Acid