title: Iron competition in fungus-plant interactions: the battle takes place in the rhizosphere.
abstract: Soilborne fungal pathogens are highly persistent and provoke important crop losses. During saprophytic and infectious stages in the soil, these organisms face situations of nutrient limitation and lack of essential elements, such as iron. We investigated the role of the bZIP transcription factor HapX as a central regulator of iron homeostasis and virulence in the vascular wilt fungus Fusarium oxysporum. This root-infecting plant pathogen attacks more than hundred different crops and is an emerging human opportunistic invader. Although iron uptake remains unaffected in a strain lacking HapX, de-repression of genes implicated in iron-consuming processes such as respiration, amino acid metabolism, TCA cycle and heme biosynthesis lead to severely impaired growth under iron-limiting conditions. HapX is required for full virulence of F. oxysporum in tomato plants and essential for infection in immunodepressed mice. Virulence attenuation of the ΔhapX strain on tomato plants is more pronounced by co-inoculation of roots with the biocontrol strain Pseudomonas putida KT2440, but not with a mutant deficient in siderophores production. These results demonstrate that HapX is required for iron competition of F. oxysporum in the tomato rhizosphere and establish a conserved role for HapX-mediated iron homeostasis in fungal infection of plants and mammals.
authors.affiliation: Departamento de Genética; Universidad de Córdoba; Córdoba, Spain; Campus de Excelencia Internacional Agroalimentario (ceiA3); Córdoba, Spain.
authors.forename: Manuel S
authors.initials: MS
authors.lastname: López-Berges
authors.affiliation: Departamento de Genética; Universidad de Córdoba; Córdoba, Spain; Campus de Excelencia Internacional Agroalimentario (ceiA3); Córdoba, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Turrà
authors.affiliation: Unitat de Microbiologia; Facultat de Medicina i Ciències de la Salut; Institut d'Investigació Sanitària Pere Virgili; Universitat Rovira i Virgili; Reus, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Capilla
authors.affiliation: Division of Molecular Biology/Biocenter; Innsbruck Medical University; Innsbruck, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Schafferer
authors.affiliation: Institut de Recherches Microbiologiques Jean-Marie Wiame; Brussels, Belgium.
authors.forename: Sandra
authors.initials: S
authors.lastname: Matthijs
authors.affiliation: Division of Molecular Biology/Biocenter; Innsbruck Medical University; Innsbruck, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Jöchl
authors.affiliation: Department of Bioengineering Sciences; Research Group Microbiology and Flanders Institute for Biotechnology; Department of Structural Biology; Vrije Universiteit Brussel; Brussels, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Cornelis
authors.affiliation: Unitat de Microbiologia; Facultat de Medicina i Ciències de la Salut; Institut d'Investigació Sanitària Pere Virgili; Universitat Rovira i Virgili; Reus, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Guarro
authors.affiliation: Division of Molecular Biology/Biocenter; Innsbruck Medical University; Innsbruck, Austria.
authors.forename: Hubertus
authors.initials: H
authors.lastname: Haas
authors.affiliation: Departamento de Genética; Universidad de Córdoba; Córdoba, Spain; Unitat de Microbiologia; Facultat de Medicina i Ciències de la Salut; Institut d'Investigació Sanitària Pere Virgili; Universitat Rovira i Virgili; Reus, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Pietro
mesh_terms: D000818:Animals; D005656:Fungal Proteins / Q000378:metabolism; D005670:Fusarium / Q000472:pathogenicity; D054884:Host-Pathogen Interactions; D007501:Iron / Q000378:metabolism*; D010944:Plants / Q000378:metabolism* / Q000382:microbiology*; D058441:Rhizosphere; D017262:Siderophores / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D017262:Siderophores; D007501:Iron
keywords: Fusarium; HapX; Pseudomonas; iron; rhizosphere; siderophores; virulence