title: Guanosine tetraphosphate modulates salicylic acid signalling and the resistance of Arabidopsis thaliana to Turnip mosaic virus.
abstract: Chloroplasts can act as key players in the perception and acclimatization of plants to incoming environmental signals. A growing body of evidence indicates that chloroplasts play a critical role in plant immunity. Chloroplast function can be regulated by the nucleotides guanosine tetraphosphate and pentaphosphate [(p)ppGpp]. In plants, (p)ppGpp levels increase in response to abiotic stress and to plant hormones which are involved in abiotic and biotic stress signalling. In this study, we analysed the transcriptome of Arabidopsis plants that over-accumulate (p)ppGpp, and unexpectedly found a decrease in the levels of a broad range of transcripts for plant defence and immunity. To determine whether (p)ppGpp is involved in the modulation of plant immunity, we analysed the susceptibility of plants with different levels of (p)ppGpp to Turnip mosaic virus (TuMV) carrying a green fluorescent protein (GFP) reporter. We found that (p)ppGpp accumulation was associated with increased susceptibility to TuMV and reduced levels of the defence hormone salicylic acid (SA). In contrast, plants with lower (p)ppGpp levels showed reduced susceptibility to TuMV, and this was associated with the precocious up-regulation of defence-related genes and increased SA content. We have therefore demonstrated a new link between (p)ppGpp metabolism and plant immunity in Arabidopsis.
authors.affiliation: Faculty of Sciences of Tunis, Laboratory of Molecular Genetics, Immunology and Biotechnology, University of Tunis El Manar, 2092 Elmanar Tunis, Tunisia.|CEA, CNRS, Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, Biologie Végétal et Microbiologie Environnemental, Bioscience and Biotechnology Institute of Aix-Marseille, Aix Marseille Université, Marseille, 13009, France.
authors.forename: Hela
authors.initials: H
authors.lastname: Abdelkefi
authors.affiliation: CEA, CNRS, Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, Biologie Végétal et Microbiologie Environnemental, Bioscience and Biotechnology Institute of Aix-Marseille, Aix Marseille Université, Marseille, 13009, France.
authors.forename: Matteo
authors.initials: M
authors.lastname: Sugliani
authors.affiliation: CEA, CNRS, Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, Biologie Végétal et Microbiologie Environnemental, Bioscience and Biotechnology Institute of Aix-Marseille, Aix Marseille Université, Marseille, 13009, France.
authors.forename: Hang
authors.initials: H
authors.lastname: Ke
authors.affiliation: CEA, CNRS, Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, Biologie Végétal et Microbiologie Environnemental, Bioscience and Biotechnology Institute of Aix-Marseille, Aix Marseille Université, Marseille, 13009, France.
authors.forename: Seddik
authors.initials: S
authors.lastname: Harchouni
authors.affiliation: Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, Bâtiment 630, Orsay, 91405, France.|Paris Diderot, Sorbonne Paris-Cité, Institute of Plant Sciences Paris-Saclay IPS2, Bâtiment 630, Orsay, 91405, France.
authors.forename: Ludivine
authors.initials: L
authors.lastname: Soubigou-Taconnat
authors.affiliation: Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, 78000, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Citerne
authors.affiliation: Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, 78000, France.
authors.forename: Gregory
authors.initials: G
authors.lastname: Mouille
authors.affiliation: Faculty of Sciences of Tunis, Laboratory of Molecular Genetics, Immunology and Biotechnology, University of Tunis El Manar, 2092 Elmanar Tunis, Tunisia.
authors.forename: Hatem
authors.initials: H
authors.lastname: Fakhfakh
authors.affiliation: CEA, CNRS, Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, Biologie Végétal et Microbiologie Environnemental, Bioscience and Biotechnology Institute of Aix-Marseille, Aix Marseille Université, Marseille, 13009, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Robaglia
authors.affiliation: CEA, CNRS, Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, Biologie Végétal et Microbiologie Environnemental, Bioscience and Biotechnology Institute of Aix-Marseille, Aix Marseille Université, Marseille, 13009, France.
authors.forename: Ben
authors.identifier: 0000-0003-2142-4606
authors.initials: B
authors.lastname: Field
mesh_terms: D017360:Arabidopsis / Q000378:metabolism* / Q000821:virology*; D002736:Chloroplasts / Q000378:metabolism; D006159:Guanosine Tetraphosphate / Q000378:metabolism*; D057865:Plant Immunity / Q000502:physiology; D017800:Potyvirus / Q000276:immunology / Q000472:pathogenicity*; D020156:Salicylic Acid / Q000378:metabolism*
chemical_list: D006159:Guanosine Tetraphosphate; D020156:Salicylic Acid
keywords: (p)ppGpp; TuMV; Turnip mosaic virus; chloroplast; guanosine tetraphosphate; pathogen; salicylic acid