Calcium-rich hypha encrustations on Piloderma

Piloderma species are broad-host-range fungi associated with a wide variety of conifer and hardwood species to form ectomycorrhizae (ECM). In this study, we investigated the hypha crystals collected from Piloderma– Picea glauca× engelmannii ECM as an initial step in the elucidation of the role of mycorrhizal fungi in mineral weathering and nutrient cycling. We compared the morphology and composition of hypha encrustation between field and cultured Piloderma samples. For field samples, the morphology of encrustations was dominated by elongated crystals often underlain by verrucose crystals. Cultured samples had mostly verrucose crystals. Generally, encrustations on field samples had higher calcium contents than cultured samples. Calcium contents ranged from 3% in the verrucose crystals of cultured samples to 17% in verrucose and elongated crystals of field samples. Encrustations had infrared absorption bands at 1333 and 781 cm^–1 wavenumbers, indicative of the presence of oxalate. High amounts of C and O in verrucose crystals are likely associated with the crystal sheath around all encrustations. This composition suggests an intracellular origin for the crystals. It is possible that encrustations start as verrucose crystals and develop into euhedral elongated crystals susceptible to dislod- gement into the soil environment. These crystals may prevent the desiccation of the hyphae and inhibit the build-up of calcium and oxalate in fungus cells. Accepted: 15 October 2000