title: Model systems to unravel the molecular mechanisms of heavy metal tolerance in the ericoid mycorrhizal symbiosis.
abstract: Ericoid mycorrhizal plants dominate in harsh environments where nutrient-poor, acidic soil conditions result in a higher availability of potentially toxic metals. Although metal-tolerant plant species and ecotypes are known in the Ericaceae, metal tolerance in these plants has been mainly attributed to their association with ericoid mycorrhizal fungi. The mechanisms underlying plant protection by the fungal symbiont are poorly understood, whereas some insights have been achieved regarding the molecular mechanisms of heavy metal tolerance in the fungal symbiont. This review will briefly introduce the general features of heavy metal tolerance in mycorrhizal fungi and will then focus on the use of "omics" approaches and heterologous expression in model organisms to reveal the molecular bases of fungal response to heavy metals. Functional complementation in Saccharomyces cerevisiae has allowed the identification of several ericoid mycorrhizal fungi genes (i.e., antioxidant enzymes, metal transporters, and DNA damage repair proteins) that may contribute to metal tolerance in a metal-tolerant ericoid Oidiodendron maius isolate. Although a powerful system, the use of the yeast complementation assay to study metal tolerance in mycorrhizal symbioses has limitations. Thus, O. maius has been developed as a model system to study heavy metal tolerance mechanisms in mycorrhizal fungi, thanks to its high metal tolerance, easy handling and in vitro mycorrhization, stable genetic transformation, genomics, transcriptomic and proteomic resources.
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, Viale Mattioli 25, 10125, Turin, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Daghino
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, Viale Mattioli 25, 10125, Turin, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Martino
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, Viale Mattioli 25, 10125, Turin, Italy. silvia.perotto@unito.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Perotto
mesh_terms: D029791:Ericaceae / Q000382:microbiology* / Q000502:physiology; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005658:Fungi / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D019216:Metals, Heavy / Q000378:metabolism*; D008954:Models, Biological; D038821:Mycorrhizae / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D040901:Proteomics; D013559:Symbiosis
chemical_list: D005656:Fungal Proteins; D019216:Metals, Heavy
keywords: Ericoid mycorrhizal fungi; Metal tolerance; Omics approaches; Yeast model system