title: Rapid genotypic change and plasticity in arbuscular mycorrhizal fungi is caused by a host shift and enhanced by segregation.
abstract: Arbuscular mycorrhizal fungi (AMF) are among the most abundant symbionts of plants, improving plant productivity and diversity. They are thought to mostly grow vegetatively, a trait assumed to limit adaptability. However, AMF can also harbor genetically different nuclei (nucleotypes). It has been shown that one AMF can produce genotypically novel offspring with proportions of different nucleotypes. We hypothesized that (1) AMF respond rapidly to a change of environment (plant host) through changes in the frequency of nucleotypes; (2) genotypically novel offspring exhibit different genetic responses to environmental change than the parent; and (3) genotypically novel offspring exhibit a wide range of phenotypic plasticity to a change of environment. We subjected AMF parents and offspring to a host shift. We observed rapid and large genotypic changes in all AMF lines that were not random. Genotypic and phenotypic responses were different among offspring and their parents. Even though growing vegetatively, AMF offspring display a broad range of genotypic and phenotypic changes in response to host shift. We conclude that AMF have the ability to rapidly produce variable progeny, increasing their probability to produce offspring with different fitness than their parents and, consequently, their potential adaptability to new environmental conditions. Such genotypic and phenotypic flexibility could be a fast alternative to sexual reproduction and is likely to be a key to the ecological success of AMF.
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
authors.forename: Caroline
authors.initials: C
authors.lastname: Angelard
authors.affiliation: Ecology Center, Utah State University, Logan, UT, USA.
authors.forename: Colby J
authors.initials: CJ
authors.lastname: Tanner
authors.affiliation: Broad Institute of MIT and Harvard, Cambridge, MA, USA.
authors.forename: Pierre
authors.initials: P
authors.lastname: Fontanillas
authors.affiliation: Institute for Work and Health, University of Lausanne and Geneva, Lausanne, Switzerland.
authors.forename: Hélène
authors.initials: H
authors.lastname: Niculita-Hirzel
authors.affiliation: 1] Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland [2] Vital-IT Group, Swiss Institute for Bioinformatics, University of Lausanne, Lausanne, Switzerland.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Masclaux
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Sanders
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D054458:Amplified Fragment Length Polymorphism Analysis; D004777:Environment; D016681:Genome, Fungal; D005838:Genotype; D054884:Host-Pathogen Interactions; D016014:Linear Models; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D010944:Plants / Q000382:microbiology*
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