Abstract：
Heavy metal pollution possesses potential hazards to plant, animal and human health, which has become the focus of recent attention. Hence, phytoremediation has been regarded as one of the most important remediation technologies for heavy-metal-contaminated soils. In this research, a dominant mine tailing plant, Macleaya cordata, was used as the experimental material to compare the metal transport and oxidative stress response in its roots under lead (Pb) and zinc (Zn) treatments. The result showed that Pb was mainly accumulated in the roots of M. cordata under the Pb treatment; less than 1% Pb was transported to the parts above. An analysis of the Zn content demonstrated a 39% accumulation in the shoots. The production of reactive oxygen species was detected using the in situ histological staining of roots, which showed that hydrogen peroxide in the root tips was observed to increase with the increase in both Pb and Zn concentrations. No significant superoxide anion changes were noted in the root tips under the Pb treatment. An analysis of the root enzyme activity showed that increase in NADPH oxidase activity can be responsible for the production of superoxide anions, subsequent the inhibition of root growth and decrease in antioxidant enzyme activities in the roots of M. cordata exposed to excess Zn. In total, this research provides evidence that the root of M. cordata has a high antioxidant capacity for Pb stress, so it can accumulate more Pb without oxidative damage. On the other hand, the Zn accumulated in the roots of M. cordata causes oxidative damage to the root tips, which can stimulate more Zn transport to the shoots to reduce the damage to the roots. This result will provide a basis for the application of M. cordata in the phytoremediation of soil polluted by Pb-Zn compounds.
摘要：
重金属污染对植物具有潜在的危害,动物和人类健康，这已经成为最近关注的焦点。因此，植物修复被认为是重金属污染土壤最重要的修复技术之一。在这项研究中,占主导地位的尾矿厂，Macleayacordata,用作实验材料，以比较铅（Pb）和锌（Zn）处理下其根部的金属运输和氧化应激反应。结果表明，Pb处理主要积累在M.cordata的根部；不到1％的Pb被输送到上述部分。对Zn含量的分析表明，芽中积累了39％。使用根的原位组织学染色检测活性氧的产生，结果表明，根尖中的过氧化氢随着Pb和Zn浓度的增加而增加。在Pb处理下，根尖没有发现明显的超氧阴离子变化。根酶活性的分析表明，NADPH氧化酶活性的增加可能是超氧阴离子产生的原因，随后，暴露于过量锌的M.cordata的根的根生长受到抑制，抗氧化酶活性降低。总的来说,这项研究提供了证据，证明了M.cordata的根对Pb胁迫具有较高的抗氧化能力，所以它可以积累更多的铅而没有氧化损伤。另一方面,根中积累的锌会对根尖造成氧化损伤，这可以刺激更多的Zn运输到芽，以减少对根部的伤害。该结果将为M.cordata在Pb-Zn化合物污染土壤的植物修复中的应用提供依据。
