title: Protozoa enhance foraging efficiency of arbuscular mycorrhizal fungi for mineral nitrogen from organic matter in soil to the benefit of host plants.
abstract: Dead organic matter (OM) is a major source of nitrogen (N) for plants. The majority of plants support N uptake by symbiosis with arbuscular mycorrhizal (AM) fungi. Mineralization of N is regulated by microfauna, in particular, protozoa grazing on bacteria. We hypothesized that AM fungi and protozoa interactively facilitate plant N nutrition from OM. In soil systems consisting of an OM patch and a root compartment, plant N uptake and consequences for plant carbon (C) allocation were investigated using stable isotopes. Protozoa mobilized N by consuming bacteria, and the mobilized N was translocated via AM fungi to the host plant. The presence of protozoa in both the OM and root compartment stimulated photosynthesis and the translocation of C from the host plant via AM fungi into the OM patch. This stimulated microbial activity in the OM patch, plant N uptake from OM and doubled plant growth. The results indicate that protozoa increase plant growth by both mobilization of N from OM and by protozoa-root interactions, resulting in increased C allocation to roots and into the rhizosphere, thereby increasing plant nutrient exploitation. Hence, mycorrhizal plants need to interact with protozoa to fully exploit N resources from OM.
authors.affiliation: Université de Lorraine UMR 1121 INRA Agronomie et Environnement Nancy-Colmar, BP 172, 54505, Vandoeuvre-lès-Nancy, France.|Universität zu Köln, Zoologisches Institut, Abt. Terrestrische Ökologie, Zülpicher Straße 47b, 50674, Köln, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Koller
authors.affiliation: Universidad Nacional de Colombia, Sede Bogotá Ciudad Universitaria - Avenida Carrera 30 no. 45-03, Bogotá, Colombia.
authors.forename: Alia
authors.initials: A
authors.lastname: Rodriguez
authors.affiliation: Université de Lorraine UMR 1121 INRA Agronomie et Environnement Nancy-Colmar, BP 172, 54505, Vandoeuvre-lès-Nancy, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Robin
authors.affiliation: J.F. Blumenbach Institute of Zoology and Anthropology, Georg August University Göttingen, Berliner Straße 28, 37073, Göttingen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Scheu
authors.affiliation: Universität zu Köln, Zoologisches Institut, Abt. Terrestrische Ökologie, Zülpicher Straße 47b, 50674, Köln, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bonkowski
mesh_terms: D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis / Q000378:metabolism; D025301:Hyphae / Q000378:metabolism; D008903:Minerals / Q000378:metabolism; D038821:Mycorrhizae / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes / Q000032:analysis / Q000378:metabolism; D010788:Photosynthesis; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology*; D010943:Plantago / Q000254:growth & development* / Q000378:metabolism / Q000382:microbiology*; D012988:Soil Microbiology; D013559:Symbiosis
chemical_list: D002247:Carbon Isotopes; D008903:Minerals; D009587:Nitrogen Isotopes; D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen
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