Helmholtz Zentrum München, German Research Center for Environmental Health, Research unit Microbe-Plant Interactions, Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany.
Metallomics. 2012 Apr;4(4):333-41. doi: 10.1039/c2mt00179a. Epub 2012 Feb 28.
Typha latifolia is a plant species widely used for phytoremediation. Accumulation, localization and distribution of Pb and mineral nutrients were investigated in roots, rhizomes and leaves of Typha latifolia grown at 0, 50, 100 and 250 μM Pb concentrations in a pot experiment under controlled conditions. Bulk elemental concentrations were determined by X-ray fluorescence (XRF) spectroscopy whereas micro-proton-induced X-ray emission (micro-PIXE) was used for element localization in root and rhizome tissues. Gradual increase in bulk Pb concentrations was observed in Typha latifolia roots and rhizomes treated with increasing Pb concentrations, however in rhizomes Pb concentrations were an order of magnitude lower than in roots. In leaves Pb concentrations were around the limit of detection for XRF (~20 μg g(-1)). An increase in concentration of K and Ca in roots, rhizomes and leaves, of iron and zinc in roots and leaves, and of Mn in rhizomes was observed either at 50 and/or 100 μM Pb treatments, whereas for K and Ca in roots, rhizomes and leaves, Fe and Zn in roots and leaves and Mn in rhizomes, or at 250 μM Pb treatment the increase was seen for concentrations of Fe and Zn in rhizomes and Cu in roots. Mn concentrations decreased with Pb treatments in roots and leaves. Element localization using micro-PIXE analysis demonstrated Pb accumulation in epidermal and cortical tissues of treated roots and rhizomes, while in endodermis and vascular tissues Pb was not detected. A displacement of Ca from epidermal to cortical tissues was observed in Pb treated roots and rhizomes, pointing to cell wall immobilization of Pb as one of the tolerance mechanisms in Typha latifolia. High level of colocalization of Pb with P (r = 0.60), S (r = 0.37) and Zn (r = 0.70) was observed in Pb treated roots, while in rhizomes colocalization with the mentioned elements was still positive, but not that prominent. These results indicate that Pb may form complexes with phosphorus and sulfur compounds in roots and rhizomes, which may also represent attraction sites for binding Zn. Because of its large root and rhizome surface area acting as main sites for Pb adsorption, Typha latifolia may represent potentially efficient plant species for phytoremediation of Pb contaminated soils and waters.
宽叶香蒲是一种被广泛应用于植物修复的植物物种。在控制条件下的盆栽实验中，研究了宽叶香蒲在 0、50、100 和 250μM Pb 浓度下根、根茎和叶中 Pb 和矿物质养分的积累、定位和分布。通过 X 射线荧光（XRF）光谱法测定了大量元素浓度，而微质子诱导 X 射线发射（micro-PIXE）则用于根和根茎组织中的元素定位。随着 Pb 浓度的增加，宽叶香蒲根和根茎中的 Pb 浓度逐渐增加，但在根茎中 Pb 浓度比根低一个数量级。在叶片中，Pb 浓度接近 XRF 的检测限（约 20μg g(-1)）。在 50 和/或 100μM Pb 处理下，观察到根、根茎和叶片中 K 和 Ca、根和叶片中 Fe 和 Zn 以及根茎中 Mn 的浓度增加，而在根、根茎和叶片中 K 和 Ca、根和叶片中 Fe 和 Zn 以及根茎中 Mn 或在 250μM Pb 处理下，观察到根茎中 Fe 和 Zn 以及根中 Cu 的浓度增加。Mn 浓度随 Pb 处理在根和叶片中降低。利用 micro-PIXE 分析进行的元素定位表明，Pb 在处理过的根和根茎的表皮和皮层组织中积累，而在内皮层和维管束组织中则未检测到 Pb。在 Pb 处理过的根和根茎中，观察到 Ca 从表皮向皮层组织的位移，表明 Pb 在细胞壁中的固定是宽叶香蒲耐受机制之一。在 Pb 处理过的根中，观察到 Pb 与 P（r = 0.60）、S（r = 0.37）和 Zn（r = 0.70）的高水平共定位，而在根茎中，与这些元素的共定位仍然为正，但不那么显著。这些结果表明，Pb 可能在根和根茎中与磷和硫化合物形成复合物，这也可能代表与 Zn 结合的吸引位点。由于其较大的根和根茎表面积作为 Pb 吸附的主要位点，宽叶香蒲可能是一种具有潜在高效的植物物种，可用于修复 Pb 污染的土壤和水。
