Effects of sodium chloride on growth of ectomycorrhizal fungal isolates in culture

Abstract

We studied the tolerance of ectomycorrhizal (ECM) fungi to sodium chloride (NaCl) to find the best fungus to aid growth of Pinus thunbergii. Four ECM fungi, Cenococcum geophilum, Pisolithus tinctorius, Rhizopogon rubescens, and Suillus luteus, were grown in liquid MMN media with five different concentrations of NaCl for 30 days, and their mycelial weights were determined. Mycelial weights of P. tinctorius and R. rubescens were not significantly different between 0 mM and 200 mM, whereas those of C. geophilum and S. luteus decreased with increasing NaCl concentration, indicating that the former two species were more tolerant to higher NaCl concentrations than the latter species. We further studied the intraspecific differences in NaCl tolerance of nine P. tinctorius isolates. They were grown on MMN agar media with six different concentrations of NaCl for 21 days, and their radial growth was measured. In total, the hyphal growth at 25 mM NaCl was significantly higher than those at the other NaCl concentrations, and EC₅₀ values were confirmed at between 50 mM and 200 mM. Among the isolates, Pt03 and Pt21 showed measurable growth at 200 mM; the growth of Pt03 was not significantly different between 0 mM and 200 mM. The results indicate that there are intraspecific variations in NaCl tolerance of Pisolithus species.