CADMIUM AND MANGANESE ACCUMULATION IN PHYTOLACCA AMERICANA L. AND THE ROLES OF NON-PROTEIN THIOLS AND ORGANIC ACIDS |
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Authors: | Lu Gao Kejian Peng Yan Xia Guiping Wang Liyuan Niu Chunlan Lian |
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Affiliation: | 1. College of Life Sciences , Nanjing Agricultural University , Nanjing , the People's Republic of China;2. Hunan Research Academy of Environmental Science , Changsha , the People's Republic of China;3. Experiment Center , Henan Institute of Science and Technology , Xinxiang , the People's Republic of China;4. Asian Natural Environmental Science Center , University of Tokyo , Tokyo , Japan |
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Abstract: | Phytolacca americana L. can accumulate large amounts of heavy metals in its aerial tissues, especially cadmium (Cd) and manganese (Mn). It has great potential for use in phytoextraction of metals from multi-metal-contaminated soils. This study was conducted to further investigate the Cd- and Mn-tolerance strategies of this plant. Concentrations of non-protein thiols (NPTs) and phytochelatins (PCs) in leaves and roots increased significantly as the concentration of Cd in solution increased. The molar ratios of PCs:soluble Cd ranged from 1.8 to 3.6 in roots and 8.1 to 31.6 in leaves, suggesting that the cellular response involving PC synthesis was sufficient to complex Cd ions in the cytosol, especially that of leaves. In contrast, excess Mn treatments did not result in a significant increase in NPT or PC concentrations in leaves or roots. Oxalic acid concentrations in leaves of plants exposed to 2 or 20 mM Mn reached 69.4 to 89.3 mg (0.771 to 0.992 mmol) g–1 dry weight, respectively, which was approximately 3.7- to 8.6-fold higher than the Mn level in the 0.6 M HCl extract. Thus, oxalic acid may play an important role in the detoxification of Mn. |
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Keywords: | Cadmium Manganese Organic acid Phytochelatins Phytolacca americana |
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