Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of the Chinese Academy of Sciences, Beijing 100049, China.
J Hazard Mater. 2013 Oct 15;261:332-41. doi: 10.1016/j.jhazmat.2013.07.050. Epub 2013 Aug 1.
Non-accumulated metals in mixed metal contaminated soils may affect hyperaccumulator growth and metal accumulation and thus remediation efficiency. Two hydroponics experiments were conducted to investigate the effects of copper (Cu) on cadmium (Cd) and zinc (Zn) accumulation by the Cd/Zn hyperaccumulator Sedum plumbizincicola, Cu toxicity and plant detoxification using chemical sequential extraction of metals, sub-cellular separation, micro synchrotron radiation based X-ray fluorescence, and transmission electron microscopy. Compared with the control (0.31 μM Cu), 5-50 μM Cu had no significant effect on Cd/Zn accumulation, but Cu at 200 μM induced root cell plasmolysis and disordered chloroplast structure. The plants held Cu in the roots and cell walls and complexed Cu in insoluble forms as their main detoxification mechanisms. Exposure to 200 μM Cu for 4 days inhibited plant Cd uptake and translocation but did not affect Zn concentrations in roots and stems. Moreover, unloading of Cd and Zn from stem to leaf was restrained compared to control plants, perhaps due to Cu accumulation in leaf veins. Copper may thus interfere with root Cd uptake and restrain Cd/Zn unloading to the leaves. Further investigation of how Cu affects plant metal uptake may help elucidate the Cd/Zn hyper-accumulating mechanisms of S. plumbizincicola.
混合金属污染土壤中的非累积金属可能会影响超积累植物的生长和金属积累，从而影响修复效率。本研究采用水培实验，研究了铜（Cu）对 Cd/Zn 超积累植物垂盆草（Sedum plumbizincicola）吸收 Cd 和 Zn 的影响，以及 Cu 毒性和植物解毒机制（采用金属化学连续提取法、亚细胞分离法、基于微同步辐射的 X 射线荧光法和透射电子显微镜法）。与对照（0.31 μM Cu）相比，5-50 μM Cu 对 Cd/Zn 积累没有显著影响，但 200 μM Cu 诱导根细胞质壁分离和叶绿体结构紊乱。植物通过将 Cu 储存在根部和细胞壁中，并将 Cu 以不溶形式络合，作为主要的解毒机制。暴露于 200 μM Cu 4 天会抑制植物对 Cd 的吸收和转运，但不会影响根部和茎部的 Zn 浓度。此外，与对照植株相比，Cd 和 Zn 从茎向叶的卸载受到抑制，这可能是由于 Cu 在叶脉中的积累。因此，Cu 可能会干扰植物对根 Cd 的吸收，并抑制 Cd/Zn 向叶片的卸载。进一步研究 Cu 如何影响植物金属吸收，可能有助于阐明垂盆草吸收 Cd/Zn 的超积累机制。
