Wang Chao, Sun Qin, Wang Liya
State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, College of Environmental Science and Engineering, Hohai University, Nanjing 210098, People's Republic of China.
Environ Toxicol. 2009 Jun;24(3):271-8. doi: 10.1002/tox.20429.
Phytochelatins (PCs) have been involved in metal detoxification, and used as potential biomarkers for an evaluation of metal toxicity. However, most studies have generally been limited to high concentrations of metals. In this study, low concentrations of cadmium (Cd) (0.01-0.64 microM) usually present in moderately polluted environments were adopted to investigate Cd toxicity, PC production, and their relationship in a rooted-submerged macrophyte Vallisneria spiralis. It was observed that 0.01-0.04 microM Cd had no significant effects on the growth of this plant when compared with the control plant without Cd, whereas 0.08-0.64 microM Cd showed toxicity, as indicated by the gradual decreases of leaf and root fresh weights. Cadmium accumulation was significantly higher in leaves than in the roots. Correspondingly, PCs were induced in leaves and roots at every Cd concentrations studied, in particular 0.16-0.64 microM, which were higher in leaves than in roots. There existed a positively linear relationship between PC concentrations and Cd toxicity in leaf and root. Furthermore, the levels of glutathione (GSH) in leaves and roots increased with increasing Cd concentrations in solutions and exposure time, but the extent of such increase was lower than that of PCs. Cadmium uptake antagonized Zn uptake. Combined effects of Cd and Fe or Cd and Mn were antagonistic in leaves and synergistic in roots. On the basis of the present results, it was further suggested that PCs can be used as potential biomarkers for monitoring the metal toxicity in moderately polluted environments.
植物螯合肽（PCs）参与金属解毒，并被用作评估金属毒性的潜在生物标志物。然而，大多数研究通常局限于高浓度金属。在本研究中，采用了中等污染环境中通常存在的低浓度镉（Cd）（0.01 - 0.64微摩尔）来研究Cd毒性、PCs产生及其在沉水生根大型植物苦草中的关系。观察到，与未添加Cd的对照植物相比，0.01 - 0.04微摩尔Cd对该植物的生长没有显著影响，而0.08 - 0.64微摩尔Cd表现出毒性，叶和根鲜重逐渐降低表明了这一点。叶片中的镉积累显著高于根部。相应地，在所研究的每个Cd浓度下，叶片和根中均诱导产生了PCs，特别是0.16 - 0.64微摩尔，叶片中的PCs含量高于根部。叶片和根中PCs浓度与Cd毒性之间存在正线性关系。此外，叶片和根中谷胱甘肽（GSH）的水平随着溶液中Cd浓度的增加和暴露时间的延长而增加，但增加的程度低于PCs。镉的吸收拮抗锌的吸收。Cd与Fe或Cd与Mn的联合作用在叶片中是拮抗的，在根中是协同的。基于目前的结果，进一步表明PCs可作为监测中等污染环境中金属毒性的潜在生物标志物。
