Peer-Reviewed Journal Details
Mandatory Fields
A. Schmalenberger, A. L. Duran, A. W. Bray, J. Bridge, S. Bonneville, L. G. Benning, M. E. Romero-Gonzalez, J. R. Leake & S. A. Banwart
Scientific Reports
Oxalate secretion by ectomycorrhizal Paxillus involutus is mineral-specific and controls calcium weathering from minerals
Optional Fields
ectomycorrhiza; weathering
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 14CO2 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.
DOI: 10.1038/srep12187
Grant Details