College of Life Sciences, Nanjing Agricultural University, Nanjing, the People's Republic of China.
Int J Phytoremediation. 2013;15(4):307-19. doi: 10.1080/15226514.2012.702800.
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.
商陆（Phytolacca americana L.）能够在其地上组织中大量积累重金属，尤其是镉（Cd）和锰（Mn）。它在从多金属污染土壤中植物提取金属方面具有巨大的应用潜力。本研究旨在进一步研究该植物对 Cd 和 Mn 的耐受策略。叶片和根中非蛋白巯基（NPTs）和植物螯合肽（PCs）的浓度随着溶液中 Cd 浓度的增加而显著增加。根中 PCs:soluble Cd 的摩尔比范围为 1.8 至 3.6，叶中为 8.1 至 31.6，表明涉及 PC 合成的细胞反应足以在细胞质中络合 Cd 离子，特别是在叶中。相比之下，过量 Mn 处理不会导致叶片或根中 NPT 或 PC 浓度的显著增加。暴露于 2 或 20 mM Mn 的植物叶片中的草酸浓度分别达到 69.4 至 89.3 mg（0.771 至 0.992 mmol）g(-1)干重，约为 0.6 M HCl 提取物中 Mn 水平的 3.7 至 8.6 倍。因此，草酸可能在 Mn 的解毒中发挥重要作用。
