title: Three sympatrically occurring species of Metarhizium show plant rhizosphere specificity.
abstract: Here we tested the hypothesis that species of the soil-inhabiting insect-pathogenic fungus Metarhizium are not randomly distributed in soils but show plant-rhizosphere-specific associations. We isolated Metarhizium from plant roots at two sites in Ontario, Canada, sequenced the 5' EF-1α gene to discern Metarhizium species, and developed an RFLP test for rapid species identification. Results indicated a non-random association of three Metarhizium species (Metarhizium robertsii, Metarhizium brunneum and Metarhizium guizhouense) with the rhizosphere of certain types of plant species (identified to species and categorized as grasses, wildflowers, shrubs and trees). M. robertsii was the only species that was found associated with grass roots, suggesting a possible exclusion of M. brunneum and M. guizhouense. Supporting this, in vitro experiments showed that M. robertsii conidia germinated significantly better in Panicum virgatum (switchgrass) root exudate than did M. brunneum or M. guizhouense. M. guizhouense and M. brunneum only associated with wildflower rhizosphere when co-occurring with M. robertsii. With the exception of these co-occurrences, M. guizhouense was found to associate exclusively with the rhizosphere of tree species, predominantly Acer saccharum (sugar maple), while M. brunneum was found to associate exclusively with the rhizosphere of shrubs and trees. These associations demonstrate that different species of Metarhizium associate with specific plant types.
authors.affiliation: Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, ON L2S 3A1, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Wyrebek
authors.affiliation: Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, ON L2S 3A1, Canada.
authors.forename: Cristina
authors.initials: C
authors.lastname: Huber
authors.affiliation: Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, ON L2S 3A1, Canada.
authors.forename: Ramanpreet Kaur
authors.initials: RK
authors.lastname: Sasan
authors.affiliation: Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St Catharines, ON L2S 3A1, Canada.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bidochka
mesh_terms: D005656:Fungal Proteins / Q000235:genetics; D058507:Host Specificity; D052981:Metarhizium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D010802:Phylogeny; D018517:Plant Roots / Q000145:classification / Q000235:genetics / Q000382:microbiology; D010944:Plants / Q000145:classification / Q000235:genetics / Q000382:microbiology*; D058441:Rhizosphere; D012988:Soil Microbiology
chemical_list: D005656:Fungal Proteins; D020648:Peptide Elongation Factor 1