title: Bacterial farming by the fungus Morchella crassipes.
abstract: The interactions between bacteria and fungi, the main actors of the soil microbiome, remain poorly studied. Here, we show that the saprotrophic and ectomycorrhizal soil fungus Morchella crassipes acts as a bacterial farmer of Pseudomonas putida, which serves as a model soil bacterium. Farming by M. crassipes consists of bacterial dispersal, bacterial rearing with fungal exudates, as well as harvesting and translocation of bacterial carbon. The different phases were confirmed experimentally using cell counting and (13)C probing. Common criteria met by other non-human farming systems are also valid for M. crassipes farming, including habitual planting, cultivation and harvesting. Specific traits include delocalization of food production and consumption and separation of roles in the colony (source versus sink areas), which are also found in human agriculture. Our study evidences a hitherto unknown mutualistic association in which bacteria gain through dispersal and rearing, while the fungus gains through the harvesting of an additional carbon source and increased stress resistance of the mycelium. This type of interaction between fungi and bacteria may play a key role in soils.
authors.affiliation: Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, , Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland, Laboratory of Eco-ethology, Institute of Biology, University of Neuchâtel, , Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland, Institute of Earth Sciences, University of Lausanne, , Geopolis, 1015 Lausanne, Switzerland, Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, , 04318 Leipzig, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Pion
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Spangenberg
authors.forename: Anaele
authors.initials: A
authors.lastname: Simon
authors.forename: Saskia
authors.initials: S
authors.lastname: Bindschedler
authors.forename: Coralie
authors.initials: C
authors.lastname: Flury
authors.forename: Auriel
authors.initials: A
authors.lastname: Chatelain
authors.forename: Redouan
authors.initials: R
authors.lastname: Bshary
authors.forename: Daniel
authors.initials: D
authors.lastname: Job
authors.forename: Pilar
authors.initials: P
authors.lastname: Junier
mesh_terms: D001203:Ascomycota / Q000378:metabolism / Q000502:physiology*; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism; D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D064307:Microbiota; D012988:Soil Microbiology
chemical_list: D015415:Biomarkers
keywords: Morchella crassipes; Pseudomonas putida; dispersal; exudate consumption; mutualism; sclerotia and melanization