土壤中镉对丛枝菌根真菌Glomus mosseae生长的效应

采用分室培养法,在同一宿主植物生长的土壤中设含有0、5、25、50mg/kg4个不同浓度重金属镉的菌丝生长室(用30μm尼龙网与根系隔开)以期建立在宿主植物生长状况完全相同的条件下研究环境因素对AM真菌直接影响的新方法,并在此基础上探讨不同浓度的重金属镉对丛枝菌根真菌Glomus mosseae(BEG167)生长的直接影响。结果表明,与不施加镉的处理相比,土壤中施加低浓度镉(5mg/kg)刺激了G.mosseae的生长,其菌丝总长度最大;高浓度镉(大于25mg/kg)抑制了G.mosseae的生长,其菌丝总长度较小。AM真菌的代谢活性与土壤镉浓度的关系也表现出与菌丝生物量相同的规律。以上结果表明:G.mosseae在镉污染环境中有应激反应的特征,即:当G.mosseae受到轻微毒害时,为了适应其生存条件的改变而不断增加其代谢活性和生长量来降低镉的毒害。此外,本方法用于研究宿主植物生长状况相同的条件下,重金属毒害或其他环境因素对AM真菌生长代谢的直接影响是可行的。

THE DIRECT EFFECT OF CADMIUM IN SOIL ON GROWTH OF ARBUSCULAR MYCORRHIZAL FUNGI GLOMUS MOSSEAE

A compartment cultivation system was developed to study the direct effect of cadmium in soil on the growth of arbuscular mycorrhiza(AM)fungus Glomus mosseae (BEG167) under the same host growing conditions. Hyphal compartments with four different cadmium concentrations, 0, 5, 25, 50mg/kg, respectively, were put into the same root compartment, and each cadmium concentration was replicated eight times. The results showed that total hyphal length of G .mosseae was the highest at 5 mg/kg of Cd concentration, indicating the lower soil Cd concentration could stimulate the growth of G. mosseae as compared with the treatment without Cd. However, at high concentrations of 25, 50mg/kg, hyphal length of G. mosseae was inhibited and was much lower. Moreover, the tendency of the metabolic activity of G. mosseae accorded with the fungal biomass under different Cd concentrations. The results suggested that G. mosseae in Cd polluted environment could survive by increasing the metabolic activity and biomass to resist on the Cd toxicity. In addition, it was shown that this method was suitable to study the direct effect of heavy metal on the AM fungi under the same plant growing condition.