title: The aquaporin gene family of the ectomycorrhizal fungus Laccaria bicolor: lessons for symbiotic functions.
abstract: Soil humidity and bulk water transport are essential for nutrient mobilization. Ectomycorrhizal fungi, bridging soil and fine roots of woody plants, are capable of modulating both by being integrated into water movement driven by plant transpiration and the nocturnal hydraulic lift. Aquaporins are integral membrane proteins that function as gradient-driven water and/or solute channels. Seven aquaporins were identified in the genome of the ectomycorrhizal basidiomycete Laccaria bicolor and their role in fungal transfer processes was analyzed. Heterologous expression in Xenopus laevis oocytes revealed relevant water permeabilities for three aquaporins. In fungal mycelia, expression of the corresponding genes was high compared with other members of the gene family, indicating the significance of the respective proteins for plasma membrane water permeability. As growth temperature and ectomycorrhiza formation modified gene expression profiles of these water-conducting aquaporins, specific roles in those aspects of fungal physiology are suggested. Two aquaporins, which were highly expressed in ectomycorrhizas, conferred plasma membrane ammonia permeability in yeast. This indicates that these proteins are an integral part of ectomycorrhizal fungus-based plant nitrogen nutrition in symbiosis.
authors.affiliation: Interfaculty Institute of Microbiology and Infection Medicine, Physiological Ecology of Plants, University of Tübingen, Tübingen, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Dietz
authors.affiliation: Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, University of Kiel, Kiel, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: von Bülow
authors.affiliation: Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, University of Kiel, Kiel, Germany.
authors.forename: Eric
authors.initials: E
authors.lastname: Beitz
authors.affiliation: Faculty for Biology and Chemistry, Botany, University of Bremen, Bremen, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Nehls
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000818:Animals; D020346:Aquaporins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D002463:Cell Membrane Permeability; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D016681:Genome, Fungal; D055399:Laccaria / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005810:Multigene Family; D009865:Oocytes; D010802:Phylogeny; D013559:Symbiosis; D013696:Temperature; D014867:Water / Q000378:metabolism; D014982:Xenopus laevis; D015003:Yeasts
chemical_list: D020346:Aquaporins; D005656:Fungal Proteins; D014867:Water; D000641:Ammonia