Copper resistance of different ectomycorrhizal fungi such as Pisolithus microcarpus, Pisolithus sp., Scleroderma sp. and Suillus sp.

Environments contaminated with heavy metals negatively impact the living organisms. Ectomy­corrhizal fungi have shown important role in these impacted sites. Thus, this study aimed to evaluate the copper-resistance of ectomycorrhizal fungi isolates Pisolithus microcarpus - UFSC-Pt116; Pisolithus sp. - UFSC-PT24, Suillus sp. - UFSM RA 2.8 and Scleroderma sp. - UFSC-Sc124 to different copper doses in solid and liquid media. The copper doses tested were: 0.00, 0.25, 0.5, 0.75, 1.0 and 1.25 mmol L-1 in the solid medium and 0.00, 0.32, 0.64 and 0.96 mmol L-1 in the liquid medium. Copper was amended as copper sulphate in order to supplement the culture medium MNM at pH 4.8, with seven replicates to each fungus-dose combination. The fungal isolates were incubated for 30 days at 28 °C. UFSC-Pt116 showed high copper-resistance such as accessed by CL50 determinations (concentration to reduce 50% of the growth) as while as UFSC-PT24 displayed copper-resistance mechanism at 0.50 mmol L-1 in solid medium. The UFSC-PT24 and UFSC-Sc124 isolates have increased copper-resistance in liquid medium. The higher production of extracellular pigment was detected in UFSC-Pt116 cultures. The UFSC-Pt116 and UFSC-PT24 isolates showed higher resistance for copper and produced higher mycelium biomass than the other isolates. In this way, the isolates UFSG-Pt116 and UFSC-PT24 can be important candidates to survive in copper-contaminated areas, and can show important role in plants symbiosis in these contaminated sites.

Heavy metal toxicity on dehydrogenase activity on rhizospheric soil of ectomycorrhizal pine seedlings in field condition.

The present investigation was carried out to study the toxicity of heavy metals (Zn, Cd, Cu, Ni, Pb and Al) on the dehydrogenase activity of ectomycorrhizal (Suillus leutus, Scleroderma aurantium, Cenococcum graniforme and Boletus spp.) and non-mycorrhizal rhizospheric soil of pine seedlings. The treatment of heavy metals adversely affected the dehydrogenase activity. Inoculation of mixed ectomycorrhizal fungi harbored increased activity of dehydrogenase. It was observed that in absence of ectomycorrhizae, heavy metals drastically reduced the enzyme activity at higher concentration of metals.