Ectomycorrhizal symbiosis can play a crucial role in protecting plant roots from heavy metals. However, a high heavy metal contamination can inhibit ectomycorrhizal fungi growth and activity, negatively influencing mycorhizal symbiosis. The growth of nine isolates of Pisolithus tinctorius, two of Suillus bovinus and one of Scleroderma sp. was assessed to evaluate the effect of Zn, Cd, Cu and Pb contaminated soil-sand mixes added to the liquid culture media, at different proportions. Addition of contaminated soil to the media reduced mycelial growth of all isolates, except of PT-306 at media with low proportion of contaminated soil mixes. The isolates showed inter and intra-specific variations in multiple contaminated soil. In general, Pisolithus isolates were more tolerant than those of S. bovinus or Scleroderma sp., with PT-306 being the most tolerant. S. bovinus isolates considered tolerant to Zn were sensitive to multiple soil contamination. Production of extracellular pigments by PT-306 and SB was enhanced by either addition of contaminated soil and a larger production of PT-306 pigments can be involved with its greater tolerance to heavy metals. PT-306 growth was favored by the addition of a low proportion of contaminated soil into the media. The addition of heavy metal contaminated soil into media was efficient to assess the impact of heavy metal multi contamination on ectomycorrhizal fungi.
ectomycorrhizal fungi; heavy metal; tolerance; toxicity; pigments