| There are some seriously problems to environment and human healthy that mine areas soils have been polluted by some heavy metals such as Cadmium (Cd) and lead (Pb). Many researches have been proved that one of useful methods for controlling and restoring ecological environmental is to find or cultivate large biomass, rapid growth hyperaccumulators. Plants of Lantana camara L., source from hangyuan country, fuquan mine area, Sichuang province, China, were cultivated by pots for exploring its tolerance mechanism and accumulation characteristics to Cd and lead Pb. The results showed:(1) Growth of plants was promoted by Cd at concentration between 30 to 60 mg·kg-1, but was inhibited by more than 90 mg·kg-1. Net photosynthetic rate of plants showed a trend of increasing at first then decline. And activity of SOD, POD, APX and CAT were enhanced by low Cd concentration, as a result of ROS scavenging and damage preventing. These results suggested that plants of Lantana camara L. could resisted to Cd stress, and it’s high capacity of ROS scavenging might be a mechanism of tolerance to Cd.(2) Content and accumulation of Cd in shoots and roots showed a trend of increasing with Cd concentration enhancement, and content of Cd peaked at 158.5 mg-kg-1 in roots and 119.4 mg·kg-1 in shoots, accumulation peaked at 138.6 μg·plant-1 in roots and 1148.5 μg·plant-1 in shoots. The allocation proportion of Cd in cell wall in roots, stems and leaves were 23.8%～34.4%、37.0%～43.3% and 28.7%～39.8% respectively, and showed a increasing trend with Cd concentration enhancement. In soluble fraction in roots, stems and leaves of Lantana camara L. reached to 62.1%～54.2%,56.2%～45.2% and 59.8%～ 52.6%, respectively, but that in Cell membrane and organelles was lowest. Enzyme activity and Cd forms were changed by the growth of Lantana camara L. Enzyme activity and Cd content in rhizosphere were more than that in non- rhizosphere. The changing in rhizosphere soil promoted activation of Cd. These results suggested that plants of Lantana camara L. could accumulate Cd from soils, which attributed to its vacuoles compartmentalization, cell wall precipitation and rhizosphere environmental influence.(3) Growth of Lantana camara L. was promoted by 100 mg·kg-1 but inhibited by more than 600 mg·kg-1 of Pb. Pn showed a trend of increasing at first then decline with enhancement of Pb concentration. Lower concentrations of Pb treatments increased SOD, POD, APX and CAT activities, higher concentrations of Pb treatments reduced the antioxidant enzyme activities of Lantana camara L., thus resulting in accumulation of reactive oxygen species, causing a serious damage to lipid peroxidation. These results suggested that plants of Lantana camara L. could resisted to Pb stress, and it’s high capacity of ROS scavenging might be a mechanism of tolerance to Pb.(4) Content and accumulation of Pb in shoots and roots showed a trend of increasing with Pb concentration enhancement, and content of Pb peaked at 264.6 mg·kg-1 in roots and 611.9 mg·kg-1 in shoots, accumulation peaked at 474.9 μg·planf-1 in roots and 6 163.0 μg·plant-1 in shoots. The allocation proportion of Pb in cell wall in roots, stems and leaves were 33.0%～39.2%,24.4%～38.3% and 19.4%～39.4%, respectively, and showed a increasing trend with Pb concentration enhancement. In soluble fraction in roots, stems and leaves of Lantana camara L. reached to 52.9%～41.5%,56.8%～39.8% and 48.8%～ 39.1%, respectively, but that in Cell membrane and organelles was lowest. Enzyme activity and Pb forms were changed by the growth of Lantana camara L. Enzyme activity and Pb content in rhizosphere were more than that in non- rhizosphere. The changing in rhizosphere soil promoted activation of Pb. These results suggested that plants of Lantana camara L. could accumulate Pb from soils, which attributed to its vacuoles compartmentalization, cell wall precipitation and rhizosphere environmental influence.In summary, plants of Lantana camara L. appeared to high accumulation and tolerance to Cd and Pb, which should be as a good plant resource to restore soil polluted by Cd and Pb. On the other hand, based on plants of Lantana camara L. has long flowering, well performance and large of mass, it has a great potential for application in phytoremediation. |
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