title: Control of Endophytic Frankia Sporulation by Alnus Nodule Metabolites.
abstract: A unique case of microbial symbiont capable of dormancy within its living host cells has been reported in actinorhizal symbioses. Some Frankia strains, named Sp+, are able to sporulate inside plant cells, contrarily to Sp- strains. The presence of metabolically slowed-down bacterial structures in host cells alters our understanding of symbiosis based on reciprocal benefits between both partners, and its impact on the symbiotic processes remains unknown. The present work reports a metabolomic study of Sp+ and Sp- nodules (from Alnus glutinosa), in order to highlight variabilities associated with in-planta sporulation. A total of 21 amino acids, 44 sugars and organic acids, and 213 secondary metabolites were detected using UV and mass spectrometric-based profiling. Little change was observed in primary metabolites, suggesting that in-planta sporulation would not strongly affect the primary functionalities of the symbiosis. One secondary metabolite (M27) was detected only in Sp+ nodules. It was identified as gentisic acid 5-O-β-d-xylopyranoside, previously reported as involved in plant defenses against microbial pathogens. This metabolite significantly increased Frankia in-vitro sporulation, unlike another metabolite significantly more abundant in Sp- nodules [M168 = (5R)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-β-d-glucopyranoside]. All these results suggest that the plant could play an important role in the Frankia ability to sporulate in planta and allow us to discuss a possible sanction emitted by the host against less cooperative Sp+ symbionts.
authors.affiliation: 1 PRES Université de Lyon, F-69361, Lyon, France and Université Lyon 1, F-69622, Villeurbanne, France; and.|2 Laboratoire Ecologie Microbienne, UMR 5557 CNRS-Lyon1, Villeurbanne.
authors.forename: Hay
authors.initials: H
authors.lastname: Anne-Emmanuelle
authors.affiliation: 1 PRES Université de Lyon, F-69361, Lyon, France and Université Lyon 1, F-69622, Villeurbanne, France; and.|2 Laboratoire Ecologie Microbienne, UMR 5557 CNRS-Lyon1, Villeurbanne.
authors.forename: Boubakri
authors.initials: B
authors.lastname: Hasna
authors.affiliation: 1 PRES Université de Lyon, F-69361, Lyon, France and Université Lyon 1, F-69622, Villeurbanne, France; and.|2 Laboratoire Ecologie Microbienne, UMR 5557 CNRS-Lyon1, Villeurbanne.
authors.forename: Buonomo
authors.initials: B
authors.lastname: Antoine
authors.affiliation: 1 PRES Université de Lyon, F-69361, Lyon, France and Université Lyon 1, F-69622, Villeurbanne, France; and.|2 Laboratoire Ecologie Microbienne, UMR 5557 CNRS-Lyon1, Villeurbanne.
authors.forename: Rey
authors.initials: R
authors.lastname: Marjolaine
authors.affiliation: 1 PRES Université de Lyon, F-69361, Lyon, France and Université Lyon 1, F-69622, Villeurbanne, France; and.|2 Laboratoire Ecologie Microbienne, UMR 5557 CNRS-Lyon1, Villeurbanne.
authors.forename: Meiffren
authors.initials: M
authors.lastname: Guillaume
authors.affiliation: 1 PRES Université de Lyon, F-69361, Lyon, France and Université Lyon 1, F-69622, Villeurbanne, France; and.|2 Laboratoire Ecologie Microbienne, UMR 5557 CNRS-Lyon1, Villeurbanne.
authors.forename: Cotin-Galvan
authors.initials: CG
authors.lastname: Laetitia
authors.affiliation: 1 PRES Université de Lyon, F-69361, Lyon, France and Université Lyon 1, F-69622, Villeurbanne, France; and.|2 Laboratoire Ecologie Microbienne, UMR 5557 CNRS-Lyon1, Villeurbanne.
authors.forename: Comte
authors.initials: C
authors.lastname: Gilles
authors.affiliation: 1 PRES Université de Lyon, F-69361, Lyon, France and Université Lyon 1, F-69622, Villeurbanne, France; and.|2 Laboratoire Ecologie Microbienne, UMR 5557 CNRS-Lyon1, Villeurbanne.
authors.forename: Herrera-Belaroussi
authors.initials: HB
authors.lastname: Aude
mesh_terms: D029661:Alnus / Q000382:microbiology*; D002244:Carbon / Q000378:metabolism; D002264:Carboxylic Acids / Q000378:metabolism; D019069:Cell Respiration; D002851:Chromatography, High Pressure Liquid; D016002:Discriminant Analysis; D060026:Endophytes / Q000502:physiology*; D040161:Frankia / Q000502:physiology*; D055442:Metabolome; D009584:Nitrogen / Q000378:metabolism; D025341:Principal Component Analysis; D053204:Root Nodules, Plant / Q000378:metabolism*; D064210:Secondary Metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013171:Spores, Bacterial / Q000502:physiology*; D000073893:Sugars / Q000378:metabolism
chemical_list: D002264:Carboxylic Acids; D000073893:Sugars; D002244:Carbon; D009584:Nitrogen