Institute of Terrestrial Ecosystems, ETH Zurich, Universitätstr. 16, 8092 Zurich, Switzerland.
Chemosphere. 2010 Aug;80(8):901-7. doi: 10.1016/j.chemosphere.2010.04.077. Epub 2010 May 26.
The use of plants for phytoextraction of heavy metals from contaminated soil is limited by the ability of the plants to grow on these soils and take up the target metals, as well as by the availability of the metals for plant uptake in the soil solution. The hypotheses of this study were that the growth-promoting phytohormone auxin (indole-3-acetic acid, IAA) can alleviate toxic effects of metals on plants and increase metal phytoextraction in combination with the biodegradable chelating agent ethylene diamine disuccinic acid (EDDS). To test these hypotheses we performed two sets of experiments with sunflowers (Helianthusannuus L.) in hydroponic solution. In the first set of experiments, five IAA concentrations (0, 10(-12), 10(-11), 10(-10), 10(-9)M) were applied in combination with Pb (2.5 microM) or Zn (15 microM). In the second set of experiments we applied combinations of IAA (0 or 10(-10)M) and EDDS (0 or 500 microM) to Pb or Zn-stressed sunflowers. Root and shoot growth of metal-stressed plants were most effectively increased with 10(-10)M IAA, and also the extraction of both metals was significantly increased at this treatment level. IAA reduced the negative metal effects, such as reduced shoot and root dry weight, root length, root volume and root surface area. EDDS significantly decreased metal uptake by the plants, thus reducing metal stress and promoting plant growth. The combined application of IAA with EDDS significantly increased Zn uptake in comparison to EDDS only treated plants. The experiments indicate that IAA can alleviate toxic effects of Pb and Zn on plant root and shoot growth and can in combination with chelants such as EDDS increase the phytoextraction potential of these plants.
从受污染的土壤中用植物进行植物提取重金属的方法受到植物在这些土壤上生长和吸收目标金属的能力以及土壤溶液中金属对植物吸收的可用性的限制。本研究的假设是，生长促进植物激素生长素（吲哚-3-乙酸，IAA）可以减轻金属对植物的毒性作用，并与可生物降解的螯合剂乙二胺二琥珀酸（EDDS）结合增加金属的植物提取。为了检验这些假设，我们在水培溶液中用向日葵（Helianthusannuus L.）进行了两组实验。在第一组实验中，应用了五种 IAA 浓度（0、10（-12）、10（-11）、10（-10）、10（-9）M）与 Pb（2.5 microM）或 Zn（15 microM）结合。在第二组实验中，我们将 IAA（0 或 10（-10）M）和 EDDS（0 或 500 microM）的组合应用于 Pb 或 Zn 胁迫的向日葵。金属胁迫植物的根和茎生长在 10（-10）M IAA 处理下最有效地增加，并且在该处理水平下两种金属的提取也显著增加。IAA 减轻了金属的负面效应，如减少地上部和地下部干重、根长、根体积和根表面积。EDDS 显著降低了植物对金属的吸收，从而减轻了金属胁迫并促进了植物的生长。与仅用 EDDS 处理的植物相比，IAA 与 EDDS 联合应用显著增加了 Zn 的吸收。实验表明，IAA 可以减轻 Pb 和 Zn 对植物根和地上部生长的毒性作用，并可以与螯合剂如 EDDS 结合增加这些植物的植物提取潜力。
