title: The role of the antimicrobial compound 2,4-diacetylphloroglucinol in the impact of biocontrol Pseudomonas fluorescens F113 on Azospirillum brasilense phytostimulators.
abstract: Pseudomonads producing the antimicrobial metabolite 2,4-diacetylphloroglucinol (Phl) can control soil-borne phytopathogens, but their impact on other plant-beneficial bacteria remains poorly documented. Here, the effects of synthetic Phl and Phl(+) Pseudomonas fluorescens F113 on Azospirillum brasilense phytostimulators were investigated. Most A. brasilense strains were moderately sensitive to Phl. In vitro, Phl induced accumulation of carotenoids and poly-β-hydroxybutyrate-like granules, cytoplasmic membrane damage and growth inhibition in A. brasilense Cd. Experiments with P. fluorescens F113 and a Phl(-) mutant indicated that Phl production ability contributed to in vitro growth inhibition of A. brasilense Cd and Sp245. Under gnotobiotic conditions, each of the three strains, P. fluorescens F113 and A. brasilense Cd and Sp245, stimulated wheat growth. Co-inoculation of A. brasilense Sp245 and Pseudomonas resulted in the same level of phytostimulation as in single inoculations, whereas it abolished phytostimulation when A. brasilense Cd was used. Pseudomonas Phl production ability resulted in lower Azospirillum cell numbers per root system (based on colony counts) and restricted microscale root colonization of neighbouring Azospirillum cells (based on confocal microscopy), regardless of the A. brasilense strain used. Therefore, this work establishes that Phl(+) pseudomonads have the potential to interfere with A. brasilense phytostimulators on roots and with their plant growth promotion capacity.
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Couillerot
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Emeline
authors.initials: E
authors.lastname: Combes-Meynet
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Joël F
authors.initials: JF
authors.lastname: Pothier
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Floriant
authors.initials: F
authors.lastname: Bellvert
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Elita
authors.initials: E
authors.lastname: Challita
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Marie-Andrée
authors.initials: MA
authors.lastname: Poirier
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: René
authors.initials: R
authors.lastname: Rohr
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Comte
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Yvan
authors.initials: Y
authors.lastname: Moënne-Loccoz
authors.affiliation: CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France.|Université Lyon 1, Villeurbanne, France.|Université de Lyon, F-69622, Lyon, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Prigent-Combaret
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D015806:Azospirillum brasilense / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism / Q000494:pharmacology; D006885:Hydroxybutyrates / Q000378:metabolism / Q000494:pharmacology; D010572:Pest Control, Biological; D010696:Phloroglucinol / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology; D011091:Polyesters / Q000378:metabolism / Q000494:pharmacology; D011551:Pseudomonas fluorescens / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D014908:Triticum / Q000187:drug effects / Q000254:growth & development* / Q000382:microbiology; D000094122:Polyhydroxybutyrates
chemical_list: D000900:Anti-Bacterial Agents; D002338:Carotenoids; D006885:Hydroxybutyrates; D010696:Phloroglucinol; D010937:Plant Growth Regulators; D011091:Polyesters; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C059817:2,4-diacetylphloroglucinol