Abstract: A pot experiment was conducted to study the effects of different cadmium (Cd) concentrations on growth and physiological traits, chlorophyll contents, activities of antioxidant enzyme (CAT, POD and SOD), contents of osmotic adjustment substances (soluble sugar, MDA and free proline), and activity of rhizosphere soil enzymes of Pinus sylvestris var. mongolica by inoculating ectomycorrhizal fungus Suillus luteus. The results showed that after 1 month Cd stress treatment on 1-year-old P. sylvestris var. mongolica seedlings, the seedling growth and the antioxidant enzyme activities in inoculated group were higher than those in uninoculated group, and most of the indicators investigated reached significant difference levels (P<0.05). CAT and POD activities declined and then increased with the increase of Cd concentration, while SOD activity showed a symmetrical pattern between the aboveground and underground parts. Meanwhile, the determination of seedling cell osmotic regulation substances showed that the cell damage degree of inoculated group was lower than that of uninoculated group. The results indicated that inoculating ectomycorrhizal fungi could help relieve the stress of Cd of P. sylvestris var. mongolica seedlings. Under Cd stress, ectomycorrhizal fungi can effectively improve rhizosphere soil enzyme activity of P. sylvestris var. mongolica seedlings (especially the urease), and further improve the tolerance of P. sylvestris var. mongolica seedlings to heavy metal. The results can provide reference for phytoremediation of heavy metal polluted soils using woody plants.

Key words: microbial interaction, black soil, fungal community, high-throughput sequencing, molecular ecological network