In vitro salinity resistance of three ectomycorrhizal fungi

The growth models, diameter growth rates, biomass yield and Na⁺ contents of three ectomycorrhizal (ECM) fungi, Suillus bovinus (L. ex Fr.) O. Kuntze, Suillus luteus (L. ex Fr.) Gray, Boletus luridus Schaeff ex Fr., were investigated at nine NaCl levels (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 mol/L). The results showed that the growth models of the three ECM fungal species were not affected by the NaCl concentration, but the growth rates reduced with the increasing NaCl concentration. The growth rates of B. luridus and S. bovinus were significantly higher than that of S. luteus at the same NaCl level; the biomass yields of three ECM fungal species were different, S. bovinus < S. luteus < B. luridus. Of the three species, B. luridus exhibited the highest growth rates, best biomass yield, and greatest Na⁺ concentration in the mycelia over the NaCl gradient tested, indicating B. luridus has the most tolerance to NaCl stress and assimilation to Na⁺ under salt stress. The growth rate of S. luteus was the lowest, but the biomass yield and Na⁺ concentration in the mycelia were only lower than those of B. luridus. S. bovinus was the most sensitive to NaCl stress and its growth rate was faster than that of S. luteus, but the biomass yield and Na⁺ concentration in the mycelia were the lowest.