Soluble Protein and Acid Phosphatase Exuded by Ectomycorrhizal Fungi and Seedlings in Response to Excessive Cu and Cd

摘要

Fungi and their symbionts can alleviate heavy metal stress by exuding soluble proteins and enzymes.This study examined the role of soluble protein and acid phosphatase (APase) exuded by Xerocomus chrysenteron,an ectomycorrhizal fungus,and the seedlings of its symbiont,Chinese pine (Pinus tabulaeformis),under conditions of excessive Cu and Cd.The growth growing type showed that this less-studied ectomycorrhizal fungus was capable of tolerating high concentrations of Cu,and may be useful in phytoremediation.X.chrysenteron grew well at 80 mg/L Cu,and the EC50 for Cd was 17.82 mg/L.X.chrysenteron showed enhanced exudation of soluble protein in both isolated and inoculated cultivation under the influence of Cu and Cd.However,soluble protein exudation differed under Cu and Cd stress in isolates.In medium with Cu,soluble protein exudation increased with concentration,but in medium with Cd,the content of soluble protein increased to a comparable level at all concentrations.We demonstrated that soluble protein was related to heavy metal tolerance,but the different ions played different roles.APase activity in exudates of fungi and seedlings decreased in both Cu and Cd stress compared to control,but in seedlings the activity was maintained by inoculation.Thus,X.chrysenteron helped the plant to maintain a normal nutrient uptake to protect it from heavy metal toxicity.