『Abstract
　Biological weathering is a function of biotic energy expenditure. Growth and metabolism of organisms generates acids and chelators, selectively absorbs nutrient ions, and applies turgor pressure and other physical forces which, in concert, chemically and physically alter minerals. In unsaturated soil environments, plant roots normally form symbiotic mycorrhizal associations with fungi. The plants provide photosynthate-carbohydrate-energy to the fungi in return for nutrients absorbed from the soil and released from minerals. In ectomycorrhiza, one of the two major types of mycorrhiza of trees, roots are sheathed in fungus, and 15-30％ of the net photosynthate of the plants passes through these fungi into the soil and virtually all of the water and nutrients taken up by the plants are supplied through the fungi. Here we show that ectomycorrhizal fungi actively forage for minerals and act as biosensors that discriminate between different grain sizes (53-90μm, 500-1000μm) and different minerals (apatite, biotite, quartz) to favour grains with a high surface-area to volume ratio and minerals with the highest P content. Growth and carbon allocation of the fungi is preferentially directed to intensively interact with these selected minerals to maximize resource foraging.

Keywords: ectomycorrhiza; organic acid exudation; oxalic acid; particle size; biological weathering; apatite; biotite; quartz』

Introduction
Materials and methods
　Aseptic root and fungal symbiosis
　Experimental microcosms to study plant-to-fungus C fluxes and C allocation to mineral weathering
　Tracing C allocation from photosynthesis to fungal weathering
　Plant-to-fungus C flux into weathering arenas
　Mycorrhiza weathering budgets
Results
Conclusions
Acknowledgements
References