title: Oxalate secretion by ectomycorrhizal Paxillus involutus is mineral-specific and controls calcium weathering from minerals.
abstract: Trees and their associated rhizosphere organisms play a major role in mineral weathering driving calcium fluxes from the continents to the oceans that ultimately control long-term atmospheric CO2 and climate through the geochemical carbon cycle. Photosynthate allocation to tree roots and their mycorrhizal fungi is hypothesized to fuel the active secretion of protons and organic chelators that enhance calcium dissolution at fungal-mineral interfaces. This was tested using (14)CO2 supplied to shoots of Pinus sylvestris ectomycorrhizal with the widespread fungus Paxillus involutus in monoxenic microcosms, revealing preferential allocation by the fungus of plant photoassimilate to weather grains of limestone and silicates each with a combined calcium and magnesium content of over 10 wt.%. Hyphae had acidic surfaces and linear accumulation of weathered calcium with secreted oxalate, increasing significantly in sequence: quartz, granite < basalt, olivine, limestone < gabbro. These findings confirmed the role of mineral-specific oxalate exudation in ectomycorrhizal weathering to dissolve calcium bearing minerals, thus contributing to the geochemical carbon cycle.
authors.affiliation: 1] Cell-Mineral Research Centre, Kroto Research Institute, University of Sheffield, S3 7HQ, UK [2] Animal and Plant Sciences, University of Sheffield, S10 2TN, UK [3] Life Sciences, University of Limerick, Limerick, Ireland.
authors.forename: A
authors.initials: A
authors.lastname: Schmalenberger
authors.affiliation: Animal and Plant Sciences, University of Sheffield, S10 2TN, UK.
authors.forename: A L
authors.initials: AL
authors.lastname: Duran
authors.affiliation: Earth Surface Science Institute, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: A W
authors.initials: AW
authors.lastname: Bray
authors.affiliation: Cell-Mineral Research Centre, Kroto Research Institute, University of Sheffield, S3 7HQ, UK.
authors.forename: J
authors.initials: J
authors.lastname: Bridge
authors.affiliation: Earth Surface Science Institute, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: S
authors.initials: S
authors.lastname: Bonneville
authors.affiliation: 1] Earth Surface Science Institute, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK [2] GFZ, German Research Centre for Geosciences, Telegrafenberg, Potsdam 14473, Germany.
authors.forename: L G
authors.initials: LG
authors.lastname: Benning
authors.affiliation: Cell-Mineral Research Centre, Kroto Research Institute, University of Sheffield, S3 7HQ, UK.
authors.forename: M E
authors.initials: ME
authors.lastname: Romero-Gonzalez
authors.affiliation: Animal and Plant Sciences, University of Sheffield, S10 2TN, UK.
authors.forename: J R
authors.initials: JR
authors.lastname: Leake
authors.affiliation: Cell-Mineral Research Centre, Kroto Research Institute, University of Sheffield, S3 7HQ, UK.
authors.forename: S A
authors.initials: SA
authors.lastname: Banwart
mesh_terms: D002118:Calcium / Q000378:metabolism*; D018613:Microscopy, Confocal; D008903:Minerals / Q000378:metabolism*; D038821:Mycorrhizae / Q000378:metabolism*; D019815:Oxalic Acid / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D013559:Symbiosis
chemical_list: D008903:Minerals; D019815:Oxalic Acid; D002118:Calcium