title: Carbon dynamics in mycorrhizal symbioses is linked to carbon costs and phosphorus benefits.
abstract: The nutrient and carbon (C) allocation dynamics in mycorrhizal hyphal networks cause variation in costs and benefits for individual plants and fungi and influence the productivity, diversity and C cycling in ecosystems. We manipulated light and phosphorus (P) availability in a pot experiment with Trifolium subterraneum colonised by the arbuscular mycorrhizal (AM) fungus Glomus intraradices. Stable (13)C-labelling was used to trace assimilated CO(2) to the mycorrhizal fungus in roots and soil using compound-specific isotope ratio mass spectrometry. We used the neutral lipid fatty acid 16:1omega5 as a signature for AM fungal storage lipids. Both P and shading reduced the AM fungal lipid accumulation in the intraradical mycelium, while only P reduced the amount of lipids in the extraradical mycelium. Recently assimilated plant C was only allocated to the mycorrhizal fungus to a small extent when plant mycorrhizal benefit was reduced by P fertilization, while increasing the plant C cost by shading did not reduce the C flow to the fungus. These results are of importance for our conception of mycorrhizal dynamics during periods of shade in nature.
authors.affiliation: Department of Plant Ecology and Systematics, Lund University, Lund, Sweden. pal_axel.olsson@ekol.lu.se
authors.forename: Pål Axel
authors.initials: PA
authors.lastname: Olsson
authors.forename: Jannice
authors.initials: J
authors.lastname: Rahm
authors.forename: Nasser
authors.initials: N
authors.lastname: Aliasgharzad
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes; D005227:Fatty Acids / Q000032:analysis; D005308:Fertilizers; D055137:Glomeromycota / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism; D025301:Hyphae / Q000737:chemistry; D008027:Light; D008055:Lipids / Q000032:analysis; D025282:Mycelium / Q000737:chemistry; D038821:Mycorrhizae / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D018520:Plant Shoots / Q000737:chemistry / Q000254:growth & development; D013559:Symbiosis; D029921:Trifolium / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism / Q000382:microbiology*
chemical_list: D002247:Carbon Isotopes; D005227:Fatty Acids; D005308:Fertilizers; D008055:Lipids; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen