title: Carbon and nitrogen metabolism in mycorrhizal networks and mycoheterotrophic plants of tropical forests: a stable isotope analysis.
abstract: Most achlorophyllous mycoheterotrophic (MH) plants obtain carbon (C) from mycorrhizal networks and indirectly exploit nearby autotrophic plants. We compared overlooked tropical rainforest MH plants associating with arbuscular mycorrhizal fungi (AMF) to well-reported temperate MH plants associating with ectomycorrhizal basidiomycetes. We investigated (13)C and (15)N abundances of MH plants, green plants, and AMF spores in Caribbean rainforests. Whereas temperate MH plants and fungi have higher δ(13)C than canopy trees, these organisms displayed similar δ(13)C values in rainforests, suggesting differences in C exchanges. Although temperate green and MH plants differ in δ(15)N, they display similar (15)N abundances, and likely nitrogen (N) sources, in rainforests. Contrasting with the high N concentrations shared by temperate MH plants and their fungi, rainforest MH plants had lower N concentrations than AMF, suggesting differences in C/N of exchanged nutrients. We provide a framework for isotopic studies on AMF networks and suggest that MH plants in tropical and temperate regions evolved different physiologies to adapt in diverging environments.
authors.affiliation: Botanical Institute, University of Basel, CH-4056 Basel, Switzerland.
authors.forename: Pierre-Emmanuel
authors.initials: PE
authors.lastname: Courty
authors.forename: Florian
authors.initials: F
authors.lastname: Walder
authors.forename: Thomas
authors.initials: T
authors.lastname: Boller
authors.forename: Kurt
authors.initials: K
authors.lastname: Ineichen
authors.forename: Andres
authors.initials: A
authors.lastname: Wiemken
authors.forename: Alain
authors.initials: A
authors.lastname: Rousteau
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Selosse
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes; D052836:Heterotrophic Processes; D007553:Isotope Labeling / Q000379:methods*; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010802:Phylogeny; D018515:Plant Leaves / Q000378:metabolism; D013172:Spores, Fungal / Q000502:physiology; D014197:Trees / Q000378:metabolism* / Q000382:microbiology*; D014329:Tropical Climate
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D002244:Carbon; D009584:Nitrogen