Soluble protein and acid phosphatase exuded by ectomycorrhizal fungi andseedlings in response to excessive Cu and Cd
ZHENG Weishuang , FEI Yingheng , HUANG Yi
DOI:
Received January 26, 2009,Revised April 17, 2009, Accepted , Available online
Volume 21,2009,Pages 1667-1672
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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 type showed that this
poorly 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 also showed enhanced exudation
of soluble protein in both isolated and inoculated cultivations under the influence of Cu and Cd. Soluble protein exudation, however,
di ered under Cu and Cd stress in isolates. In mediums containing Cu, soluble protein exudation increased with concentration, but in
mediums containing Cd the content of soluble protein increased to a comparable level at all concentrations. This study demonstrated
that soluble protein was related to heavy metal tolerance, although the di erent ions played di erent roles. While APase activity in
exudates of fungi and seedlings decreased under Cu and Cd stress in comparison to the control, the APase activity in seedlings was
maintained by inoculation. Thus, X. chrysenteron facilitated the ability of plant to maintain a normal nutrient uptake, and therefore to
protect it from heavy metal toxicity.
