The effects of ectomycorrhizal fungi inoculation on alleviating Cd stress in Pinus massoniana seedlings.

Ectomycorrhizal fungi (EMF), through their symbiotic associations with plants, can effectively alleviate heavy metal toxicity in plants. Therefore, we inoculated Pinus massoniana with Suillus luteus and Suillus bovinus and exposed them to different Cd concentrations (0 mg/L and 80 mg/L CdCl2) for 20 days. Single inoculation with S. luteus and S. bovinus promoted root growth and differentiation to varying degrees, enhanced the glutathione reductase (GR) and catalase (CAT) levels in leaves. The glutathione (GSH) contents decreased in leaves and roots, whereas the malondialdehyde (MDA) content increased (although it remained significantly (p < 0.05) lower than that in the CK group. Total nitrogen (TN) decreased in leaves and roots, whereas Ca, Mg, and Mn increased in the leaves, and Fe, Mg, and Mn increased in the roots. The Cd leaf and root levels were significantly (p < 0.05) lower in the inoculated groups than in the CK. Mixed inoculation with S. luteus and S. bovinus resulted in higher Cd-translocation rates than single inoculation, whereas the Cd-retention rate was lower than found with single inoculation. These results indicate that EMF mitigate Cd-stress responses by promoting root growth, regulating nutrient element uptake, and enhancing antioxidant defense systems. These findings indicate that mycorrhizal symbiosis plays a potential role in Cd phytoremediation.