镉、铜复合污染下丛枝菌根真菌对玉米重金属吸收的影响

Effects of Arbuscular Mycorrhizal Fungi on Heavy Metal Uptake of Maize Under Cd and Cu Combined Pollution Conditions

农田重金属污染引发的环境问题日益受到关注。通过盆栽实验,开展Cd、Cu复合污染条件下丛枝菌根真菌(AMF)对玉米的接种研究,探讨了重金属污染对宿主与AMF共生的影响、AMF对玉米重金属耐受性和吸收方面的作用。结果显示,AMF具有一定的Cd、Cu耐性,但重金属处理能明显抑制AMF对玉米根系的侵染(P<0.05),尤其是减少AMF的丛枝和泡囊结构形成。重金属明显抑制了玉米的生长,但AMF能够缓解重金属的生物毒性效应,表现为玉米植株的生物量、株高的显著增加(P<0.05)。接种AMF会显著提高玉米对Cd和Cu的积累(P<0.05)。结果表明,重金属污染对农田生态系统中农作物和AMF均具有潜在的危害。在一定程度重金属污染的农田生态系统中,AMF能够改善农作物对重金属的耐性,也可能提高重金属进入人类食物链的风险。

The heavy metal contaminations in agricultural soil are a great threat to human health. In this study, a greenhouse experiment was conducted to investigate the effects of arbuscular mycorrhizal fungi （AMF） inoculation on Cd and Cu accumulation in maize under Cd- Cu combined pollutions, as well as the potential toxic effects of Cd-Cu pollution on AM symbiosis. It is shown that the heavy metal contamination significantly inhibits the symbiosis between AMF and maize （P〈0.05）, and the inhibition effects are more significant on the vesicle and arbuscular structures than on the hyphal structure of AMF. The heavy metal contamination also significantly inhibits the growth of maize （P〈0.05）, but the inhibition effects are obviously alleviated by AMF colonization. Besides, AMF inoculation significantly increases the Cd and Cu accumulations in both roots and shoots of host plants （P〈0.05）. The results from this study indicate that mild- to middle-levels of heavy metal contaminations in the agricultural soils could threat both crops and AMF. In the heavy metal contaminated farmlands, AMF could on one hand improve the tolerance of crops to heavy metals, while on the other hand increase the risks of heavy metals entering into human food chain by improving the heavy metal absorption of crop plants.