title: Double-stranded RNAs induce a pattern-triggered immune signaling pathway in plants.
abstract: Pattern-triggered immunity (PTI) is a plant defense response that relies on the perception of conserved microbe- or pathogen-associated molecular patterns (MAMPs or PAMPs, respectively). Recently, it has been recognized that PTI restricts virus infection in plants; however, the nature of the viral or infection-induced PTI elicitors and the underlying signaling pathways are still unknown. As double-stranded RNAs (dsRNAs) are conserved molecular patterns associated with virus replication, we applied dsRNAs or synthetic dsRNA analogs to Arabidopsis thaliana and investigated PTI responses. We show that in vitro-generated dsRNAs, dsRNAs purified from virus-infected plants and the dsRNA analog polyinosinic-polycytidylic acid (poly(I:C)) induce typical PTI responses dependent on the co-receptor SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE 1 (SERK1), but independent of dicer-like (DCL) proteins in Arabidopsis. Moreover, dsRNA treatment of Arabidopsis induces SERK1-dependent antiviral resistance. Screening of Arabidopsis wild accessions demonstrates natural variability in dsRNA sensitivity. Our findings suggest that dsRNAs represent genuine PAMPs in plants, which induce a signaling cascade involving SERK1 and a specific dsRNA receptor. The dependence of dsRNA-mediated PTI on SERK1, but not on DCLs, implies that dsRNA-mediated PTI involves membrane-associated processes and operates independently of RNA silencing. dsRNA sensitivity may represent a useful trait to increase antiviral resistance in cultivated plants.
authors.affiliation: Botany, Department of Environmental Sciences, University of Basel, Basel, CH-4056, Switzerland.
authors.forename: Annette
authors.initials: A
authors.lastname: Niehl
authors.affiliation: Botany, Department of Environmental Sciences, University of Basel, Basel, CH-4056, Switzerland.
authors.forename: Ines
authors.initials: I
authors.lastname: Wyrsch
authors.affiliation: Botany, Department of Environmental Sciences, University of Basel, Basel, CH-4056, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Boller
authors.affiliation: Botany, Department of Environmental Sciences, University of Basel, Basel, CH-4056, Switzerland.|Institut de Biologie Moléculaire des Plantes, CNRS UPR 2357, Strasbourg, 67000, France.
authors.forename: Manfred
authors.initials: M
authors.lastname: Heinlein
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000276:immunology* / Q000821:virology; D029681:Arabidopsis Proteins / Q000378:metabolism; D060146:Ecotype; D005408:Flagellin / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D000069452:Pathogen-Associated Molecular Pattern Molecules / Q000378:metabolism*; D010935:Plant Diseases / Q000821:virology; D057865:Plant Immunity / Q000187:drug effects / Q000235:genetics; D010942:Plant Viruses / Q000187:drug effects / Q000502:physiology; D011070:Poly I-C / Q000494:pharmacology; D012330:RNA, Double-Stranded / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D000069452:Pathogen-Associated Molecular Pattern Molecules; D012330:RNA, Double-Stranded; D005408:Flagellin; D011070:Poly I-C
keywords: Arabidopsis; RNA silencing; double-stranded RNA (dsRNA); natural variation; pathogen-associated molecular pattern (PAMP); pattern-triggered immunity (PTI); somatic embryogenesis receptor-like kinase; virus