Tolerance of ectomycorrhizal fungus mycelium to low temperature and freezing-thawing.

ABSTRACT

Very little is known about the tolerance of ectomycorrhizal fungi to the freezing and repetitive freezing-thawing in northern coniferous forests. Isolates of Cortinarius multiformis , Russula densifolia , Suillus granulatus , and Lactarius deliciosus were exposed to a series of temperatures between +4 and -40 °C. The relative electrolyte leakage test indicated that the lethal temperature for 50% of samples was between -7.6 and -13.7 °C. Resume growth experiments showed that the 4 species of ectomycorrhizal fungi had a relatively high tolerance to the low temperatures, with L. deliciosus having the highest tolerance and C. multiformis the lowest. The repeated freezing-thawing delayed the growth of mycelium, which decreased with an increase in the number of freeze-thaw cycles.