title: Kelps feature systemic defense responses: insights into the evolution of innate immunity in multicellular eukaryotes.
abstract: Brown algae are one of the few eukaryotic lineages that have evolved complex multicellularity, together with Opisthokonts (animals, fungi) and Plantae (land plants, green and red algae). In these three lineages, biotic stresses induce similar local defense reactions. Animals and land plants also feature a systemic immune response, protecting the whole organism after an attack on one of its parts. However, the occurrence of systemic defenses has never been investigated in brown algae. We elicited selected parts of the kelp Laminaria digitata and monitored distant, nonchallenged areas of the same individual for subsequent defense reactions. A systemic reaction was detected following elicitation on a distant area, including an oxidative response, an increase in haloperoxidase activities and a stronger resistance against herbivory. Based on experiments with pharmacological inhibitors, the liberation of free fatty acids is proposed to play a key role in systemic signaling, reminiscent of what is known in land plants. This study is the first report, outside the phyla of Opisthokonts and Plantae, of an intraorganism communication leading to defense reactions. These findings indicate that systemic immunity emerged independently at least three times, as a consequence of convergent evolution in multicellular eukaryotic lineages.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.|CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Thomas
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.|CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Cosse
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, FR 2424, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.|CNRS, FR 2424, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Le Panse
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, FR 2424, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.|CNRS, FR 2424, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Kloareg
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.|CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Potin
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.|CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688, Roscoff Cedex, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Leblanc
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005247:Feeding Behavior; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D006861:Hydrogen Peroxide; D007113:Immunity, Innate / Q000502:physiology*; D007795:Laminaria / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D008974:Mollusca / Q000502:physiology; D018515:Plant Leaves
chemical_list: D006861:Hydrogen Peroxide
keywords: Laminaria digitata; defense responses; elicitation; kelps; oxidative burst; systemic immune response