Koller Claudia E, Patrick John W, Rose Ray J, Offler Christina E, MacFarlane Geoff R
School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
Chemosphere. 2007 Jan;66(7):1256-63. doi: 10.1016/j.chemosphere.2006.07.029. Epub 2006 Aug 28.
The capacity of the Australian native fern Pteris umbrosa to function as an arsenic (As) hyperaccumulator (shoot:soil As concentration >1) was examined by growing plants under glasshouse conditions in an inert medium supplemented with As. Arsenic preferentially accumulated in the fronds, a trait of a hyperaccumulator. The As concentration of fronds decreased with age, being particularly high in the croziers and low in the senesced fronds. Below ground, rhizomes accumulated more As than adventitious roots. Uptake from a range of solution concentrations followed Michaelis Menten kinetics up to a soil solution As concentration of 400mgl(-1). The K(m) for As uptake by roots suggested the operation of a low-affinity carrier. The predicted Nernst membrane potential indicated that uptake was against the electrochemical gradient of As. At 600mgl(-1), the rate of As uptake increased and phytotoxic effects were indicated by a significant decline in biomass. Arsenic uptake and translocation in P. umbrosa and Pteris vittata were similar at low exposure to As. At higher exposure, As uptake and translocation by P. vittata increased more than in P. umbrosa. The growth rate of both ferns was similar, whereas the biomass distribution was not, with P. vittata having a much larger root mass. This suggests that As uptake by P. umbrosa roots was very efficient and may be improved by stimulating root growth to enhance its potential.
通过在温室条件下于添加了砷的惰性介质中种植澳大利亚本土蕨类植物蜈蚣草，研究了其作为砷超富集植物（地上部分：土壤砷浓度>1）的能力。砷优先积累在叶中，这是超富集植物的一个特征。叶中的砷浓度随年龄下降，在拳卷叶中特别高，而在衰老叶中较低。在地下，根茎比不定根积累更多的砷。从一系列溶液浓度中吸收砷遵循米氏动力学，直至土壤溶液砷浓度达到400mg l⁻¹。根部吸收砷的米氏常数表明存在低亲和力载体。预测的能斯特膜电位表明吸收是逆着砷的电化学梯度进行的。在600mg l⁻¹时，砷的吸收速率增加，生物量显著下降表明存在植物毒性效应。在低砷暴露下，蜈蚣草和 vittata 蕨的砷吸收和转运相似。在高暴露下，vittata 蕨的砷吸收和转运增加幅度大于蜈蚣草。两种蕨类植物的生长速率相似，但生物量分布不同，vittata 蕨的根质量大得多。这表明蜈蚣草根部对砷的吸收非常有效，可通过刺激根系生长来提高其潜力以进一步改善。
