Nickel and Zinc Isotope Fractionation in Hyperaccumulating and Nonaccumulating Plants
Nickel and Zinc Isotope Fractionation in Hyperaccumulating and Nonaccumulating Plants
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超积累和非积累植物中的镍和锌同位素分馏
DOI：
10.1021/es5020955
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发表时间：
2014-10-21
影响因子：
11.4
通讯作者：
Qiu, Rong-Liang
中科院分区：
文献类型：
--
作者：
Deng, Teng-Hao-Bo;Coquet, Christophe;Qiu, Rong-Liang
到目前为止，关于高等植物中镍（Ni）的同位素分馏以及植物镍和锌（Zn）内稳态如何影响这种分馏的数据很少。进行了一项水培实验，以研究植物吸收和转运过程中镍和锌的同位素分馏。将非富集植物遏蓝菜（Thlaspi arvense）、镍超富集植物庭荠（Alyssum murale）以及镍和锌超富集植物天蓝遏蓝菜（Noccaea caerulescens）种植在低（2μM）和高（50μM）镍和锌溶液中。结果表明，植物倾向于吸收较轻的镍同位素，这可能是由于跨根细胞膜的低亲和力转运系统起作用。在低锌处理下生长的超富集植物中，植物与溶液之间的镍同位素分馏更大（ΔNi - 60（植物 - 溶液）=-0.90‰到 -0.63‰），而非富集植物遏蓝菜的分馏（ΔNi - 60（植物 - 溶液）=-0.21‰）较小，这表明超富集植物中低亲和力转运系统的通透性更强。在大多数植物中观察到锌的轻同位素富集（ΔZn - 66（植物 - 溶液）=-0.23‰到 -0.10‰），但程度比镍轻。根表面对锌的快速吸收导致浓度梯度，这诱导了根际的离子扩散，并可能导致超富集植物天蓝遏蓝菜中锌的轻同位素富集。在高锌处理中，锌在吸收过程中可与镍竞争，这降低了植物中的镍浓度并减小了镍同位素分馏程度（ΔNi - 60（植物 - 溶液）=-0.11‰到 -0.07‰），表明植物可能通过锌的低亲和力转运系统吸收镍。我们提出，过渡元素的同位素组成分析可成为研究植物生理过程的一种经验工具。
Until now, there has been little data on the isotope fractionation of nickel (Ni) in higher plants and how this can be affected by plant Ni and zinc (Zn) homeostasis. A hydroponic cultivation was conducted to investigate the isotope fractionation of Ni and Zn during plant uptake and translocation processes. The nonaccumulator Thlaspi arvense, the Ni hyperaccumulator Alyssum murale and the Ni and Zn hyperaccumulator Noccaea caerulescens were grown in low (2 mu M) and high (50 mu M) Ni and Zn solutions. Results showed that plants were inclined to absorb light Ni isotopes, presumably due to the functioning of low-affinity transport systems across root cell membrane. The Ni isotope fractionation between plant and solution was greater in the hyperaccumulators grown in low Zn treatments (Delta Ni-60(plant-solution) = -0.90 to -0.63 parts per thousand) than that in the nonaccumulator T. arvense (Delta Ni-60(plant-solution) = -0.21 parts per thousand), thus indicating a greater permeability of the low-affinity transport system in hyperaccumulators. Light isotope enrichment of Zn was observed in most of the plants (Delta Zn-66(plant-solution) = -0.23 to -0.10 parts per thousand), but to a lesser extent than for Ni. The rapid uptake of Zn on the root surfaces caused concentration gradients, which induced ion diffusion in the rhizosphere and could result in light Zn isotope enrichment in the hyperaccumulator N. caerulescens. In high Zn treatment, Zn could compete with Ni during the uptake process, which reduced Ni concentration in plants and decreased the extent of Ni isotope fractionation (Delta Ni-60(plant-solution) = -0.11 to -0.07 parts per thousand), indicating that plants might take up Ni through a low-affinity transport system of Zn. We propose that isotope composition analysis for transition elements could become an empirical tool to study plant physiological processes.