Different Responses of Two Ectomycorrhizal Fungi to Cd Treatment

Abstract

Ectomycorrhizal fungi can absorb heavy metals and allow host plants to develop resistance to heavy metal stress, but their heavy metal tolerance is not fully understood. In this study, the ability of Suillus bovinus (Sb) and Suillus placidus (Sp) to tolerate cadmium (Cd) was evaluated. Sb and Sp were treated with different Cd concentrations (0 (control), 0.2, 0.4 and 0.8 mg/L) under pure culture conditions, and the biomass, osmotic adjustment substance contents (soluble sugar and soluble protein), antioxidant enzyme activities (superoxide dismutase (SOD) and catalase (CAT)), pH and conductivity were examined. Sb biomass, soluble protein content and SOD activity first increased (0.2 mg/L and 0.4 mg/L Cd) and then decreased (0.8 mg/L Cd). Sp showed a similar change rule but a smaller range. Cd treatment increased the CAT activity of Sb and Sp but significantly reduced soluble sugars in Sb mycelium, whereas 0.2 mg/L Cd significantly increased soluble sugars in Sp mycelium. The pH and conductivity in the medium of Sb treated with different Cd concentrations showed more significant changes than those of Sp. The pH of Sp at 0 mg/L Cd and conductivity at 0.8 mg/L Cd were significantly lower than those of Sb. Correlation analysis suggested that Cd affected Sb more than Sp. In general, Cd treatment had less effect on the indexes of Sp, and Sp tolerated Cd better than Sb.