Storage of ectomycorrhizal fungi by freezing

Ectomycorrhizal fungi are usually maintained by subculturing at about +25 degrees C. Ito and Yokohoma(1983) and Jong and Davis (1987) demonstrated that some ectomycorrhizal fungi could be preserved by freezing. We show that the survival of ectomycorrhizal fungi after freezing at -196 degrees C or -80 degrees C depends on the cooling rate and on the species or strains. The optimum rate of cooling is -1 degrees C per min. Thelephora terrestris and Paxillus involutus did not survive any freezing method. The resistance of Cenococcum geophillum to freezing may be related to its tolerance of water stress and of high salinity.