Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Tianhe District, Guangzhou, 510650, Guangdong, China.
Ecotoxicology. 2012 Oct;21(7):2004-11. doi: 10.1007/s10646-012-0935-y. Epub 2012 Jun 8.
The current study evaluated the toxicity of three heavy metals to aerial roots of the Chinese banyan (Ficus microcarpa), which is a tree species native to China. In a laboratory experiment, segments of aerial roots cut from trees were treated with 0, 25, 50, 100, and 200 μM of lead, cadmium, or copper (Cu). The contents of these heavy metals in cells increased and root cell viability decreased with increases in treatment concentration. High levels of reactive oxygen species accumulated in the aerial root sections after heavy metal treatment. Both biochemical assay and histochemical localization showed that O(2) (•-), which is a precursor of H(2)O(2) accumulated in root sections and that the amount accumulated was positively related to heavy metal concentration, especially for Cu-treated samples. Histochemical staining with diaminobenzidine (DAB) and a fluorometric scopoletin oxidation assay indicated that the amount of H(2)O(2) accumulated was positively related to heavy metal concentration in the treatments; the scopoletin fluorescence assay was more sensitive and efficient than DAB staining for detection and quantification of H(2)O(2). The results indicate that aerial roots are sensitive to heavy metal-induced oxidative damage and that aerial roots have the potential to be used as indicators of heavy metal pollution in urban areas.
本研究评价了三种重金属对中国榕（Ficus microcarpa）气生根的毒性，中国榕是原产于中国的树种。在实验室实验中，将取自树木的气生根切段用 0、25、50、100 和 200μM 的铅、镉或铜（Cu）处理。细胞中这些重金属的含量随着处理浓度的增加而增加，根细胞活力下降。重金属处理后，气生根段中积累了大量的活性氧。生化测定和组织化学定位都表明，O(2)（•-）作为 H(2)O(2)的前体在根段中积累，并且积累的量与重金属浓度呈正相关，尤其是 Cu 处理的样品。二氨基联苯胺（DAB）组织化学染色和荧光素氧化法测定表明，H(2)O(2)的积累量与处理中重金属浓度呈正相关；荧光素法比 DAB 染色法更灵敏、更高效，适用于检测和定量 H(2)O(2)。结果表明，气生根对重金属诱导的氧化损伤敏感，气生根有可能成为城市地区重金属污染的指示剂。
