title: Comparative genomics and expression levels of hydrophobins from eight mycorrhizal genomes.
abstract: Hydrophobins are small secreted proteins that are present as several gene copies in most fungal genomes. Their properties are now well understood: they are amphiphilic and assemble at hydrophilic/hydrophobic interfaces. However, their physiological functions remain largely unexplored, especially within mycorrhizal fungi. In this study, we identified hydrophobin genes and analysed their distribution in eight mycorrhizal genomes. We then measured their expression levels in three different biological conditions (mycorrhizal tissue vs. free-living mycelium, organic vs. mineral growth medium and aerial vs. submerged growth). Results confirmed that the size of the hydrophobin repertoire increased in the terminal orders of the fungal evolutionary tree. Reconciliation analysis predicted that in 41% of the cases, hydrophobins evolved from duplication events. Whatever the treatment and the fungal species, the pattern of expression of hydrophobins followed a reciprocal function, with one gene much more expressed than others from the same repertoire. These most-expressed hydrophobin genes were also among the most expressed of the whole genome, which suggests that they play a role as structural proteins. The fine-tuning of the expression of hydrophobin genes in each condition appeared complex because it differed considerably between species, in a way that could not be explained by simple ecological traits. Hydrophobin gene regulation in mycorrhizal tissue as compared with free-living mycelium, however, was significantly associated with a calculated high exposure of hydrophilic residues.
authors.affiliation: Centre for Environmental Sciences, Environmental Biology group, UHasselt, Hasselt, Belgium. francois.rineau@uhasselt.be.
authors.forename: F
authors.identifier: http://orcid.org/0000-0002-5135-6184
authors.initials: F
authors.lastname: Rineau
authors.affiliation: Centre for Environmental Sciences, Environmental Biology group, UHasselt, Hasselt, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Lmalem
authors.affiliation: Department of Biology, Microbial Ecology Group, Lund University, Ecology Building, 223 62, Lund, SE, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Ahren
authors.affiliation: Department of food and environmental sciences, University of Helsinki, Helsinki, Finland.
authors.forename: F
authors.initials: F
authors.lastname: Shah
authors.affiliation: Department of Biology, Microbial Ecology Group, Lund University, Ecology Building, 223 62, Lund, SE, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Johansson
authors.affiliation: Centre for Environmental Sciences, Environmental Biology group, UHasselt, Hasselt, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Coninx
authors.affiliation: Centre for Environmental Sciences, Environmental Biology group, UHasselt, Hasselt, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Ruytinx
authors.affiliation: Centre for Environmental Sciences, Environmental Biology group, UHasselt, Hasselt, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Nguyen
authors.affiliation: US Department of Energy Joint Genome Institute (JGI), Walnut Creek, CA, USA.
authors.forename: I
authors.initials: I
authors.lastname: Grigoriev
authors.affiliation: US Department of Energy Joint Genome Institute (JGI), Walnut Creek, CA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Kuo
authors.affiliation: Laboratory of Excellence Advanced Research on the Biology of Tree and Forest Ecosystems (ARBRE), Institut National de la Recherche Agronomique (INRA), UMR 1136, Champenoux, France.|Laboratory of Excellence ARBRE, University of Lorraine, UMR 1136, Champenoux, France.
authors.forename: A
authors.initials: A
authors.lastname: Kohler
authors.affiliation: Laboratory of Excellence Advanced Research on the Biology of Tree and Forest Ecosystems (ARBRE), Institut National de la Recherche Agronomique (INRA), UMR 1136, Champenoux, France.|Laboratory of Excellence ARBRE, University of Lorraine, UMR 1136, Champenoux, France.
authors.forename: E
authors.initials: E
authors.lastname: Morin
authors.affiliation: Centre for Environmental Sciences, Environmental Biology group, UHasselt, Hasselt, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Vangronsveld
authors.affiliation: Laboratory of Excellence Advanced Research on the Biology of Tree and Forest Ecosystems (ARBRE), Institut National de la Recherche Agronomique (INRA), UMR 1136, Champenoux, France.|Laboratory of Excellence ARBRE, University of Lorraine, UMR 1136, Champenoux, France.
authors.forename: F
authors.initials: F
authors.lastname: Martin
authors.affiliation: Centre for Environmental Sciences, Environmental Biology group, UHasselt, Hasselt, Belgium.
authors.forename: J V
authors.initials: JV
authors.lastname: Colpaert
mesh_terms: D005656:Fungal Proteins / Q000235:genetics*; D020440:Gene Duplication; D016681:Genome, Fungal; D023281:Genomics; D025282:Mycelium; D038821:Mycorrhizae / Q000235:genetics*
chemical_list: D005656:Fungal Proteins
keywords: Comparative genomics; Hydrophobins; Mycorrhizas; Small secreted proteins