Objective Paxillus involutus is an excellent ectomycorrhizal fungus for Populus davidiana × alba. This paper investigates its tolerance to heavy metal stress, aiming to provide data for future development of ectomycorrhizal fungal agents resistant to heavy metal stress. It also seeks to offer a theoretical basis for high-quality seedling cultivation of Populus davidiana × alba and improving its afforestation survival rate in northeastern China.

Method Using Paxillus involutus as the research subject, in vitro cultures were conducted. The changes in ectomycorrhizal fungal growth and heavy metal accumulation under different concentrations of copper (Cu) and cadmium (Cd) stress were analyzed to explore the heavy metal tolerance of Paxillus involutus.

Result (1) Under Cu²⁺ stress, Paxillus involutus grew normally at Cu²⁺ concentrations ≤ 0.3 μmol/L; its growth was inhibited at Cu²⁺ concentrations > 0.3 μmol/L. Ion energy spectrum analysis indicated that Paxillus involutus had a strong accumulation capacity for Cu²⁺. (2) Under Cd²⁺ stress, Paxillus involutus experienced the least stress and grew normally in the 0.1 μmol/L Cd²⁺ treatment group, while its growth was severely inhibited at other concentrations. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis showed that the accumulation capacity of Paxillus involutus for Cd²⁺ was inferior to that for Cu²⁺.

Conclusion Paxillus involutus exhibits a certain tolerance and accumulation capacity under Cu and Cd stress. The research results can provide a theoretical basis for scientific application of Paxillus involutus agents to enhance the afforestation survival rate of Populus davidiana × P. alba.