title: Nonself vegetative fusion and genetic exchange in the arbuscular mycorrhizal fungus Glomus intraradices.
abstract: Arbuscular mycorrhizal fungi (AMF) form symbioses with the majority of plants and form extensive underground hyphal networks simultaneously connecting the roots of different plant species. No empirical evidence exists for either anastomosis between genetically different AMF or genetic exchange.Five isolates of one population of Glomus intraradices were used to study anastomosis between hyphae of germinating spores. We show that genetically distinct AMF, from the same field, anastomose, resulting in viable cytoplasmic connections through which genetic exchange could potentially occur.Pairs of genetically different isolates were then co-cultured in an in vitro system.Freshly produced spores were individually germinated to establish new cultures.Using several molecular tools, we show that genetic exchange occurred between genetically different AMF. Specific genetic markers from each parent were transmitted to the progeny. The progeny were viable, forming symbioses with plant roots. The phenotypes of some of the progeny were significantly different from either parent.Our results indicate that considerable promiscuity could occur in these fungi because nine out of 10 combinations of different isolates anastomosed. The ability to perform genetic crosses between AMF experimentally lays a foundation for understanding the genetics and evolutionary biology of these important plants symbionts.
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Croll
authors.affiliation: Department of Crop Plant Biology, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Giovannetti
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Koch
authors.affiliation: Institute of Biology and Plant Biotechnology, UO Pisa, CNR, Via del Borghetto 80, 5 6124 Pisa, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Sbrana
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Martine
authors.initials: M
authors.lastname: Ehinger
authors.affiliation: Department of Chemistry and Biochemistry, New Mexico State University, PO Box 30001, MSC 3C, Las Cruces, NM 88003 USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Lammers
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Sanders
mesh_terms: D003433:Crosses, Genetic; D056915:DNA Copy Number Variations; D005819:Genetic Markers; D005838:Genotype; D055137:Glomeromycota / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D025301:Hyphae / Q000235:genetics / Q000502:physiology; D038821:Mycorrhizae / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D010641:Phenotype; D010802:Phylogeny; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology; D012335:RNA, Ribosomal / Q000235:genetics; D013559:Symbiosis / Q000235:genetics
chemical_list: D005819:Genetic Markers; D012335:RNA, Ribosomal