In Situ Distribution and Speciation of Toxic Copper, Nickel, and Zinc in Hydrated Roots of Cowpea
In Situ Distribution and Speciation of Toxic Copper, Nickel, and Zinc in Hydrated Roots of Cowpea
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DOI：
10.1104/pp.111.173716
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发表时间：
2011-06-01
期刊：
影响因子：
7.4
通讯作者：
Lombi, Enzo
中科院分区：
文献类型：
--
作者：
Kopittke, Peter M.;Menzies, Neal W.;Lombi, Enzo
由于人类活动对景观的污染，微量金属的植物毒性已成为全球关注的问题。利用同步辐射x射线荧光显微镜和x射线吸收光谱技术，对豇豆（Vigna unguiculata）在1.5 μ M Cu、5 μ M Ni和40 μ M Zn环境下1 ~ 24 h的水化根进行了原位检测，检测了铜（Cu）、镍（Ni）和锌（Zn）的分布和形态。暴露24 h后，大部分Cu与根皮和外皮层的聚半乳糖醛酸结合。这表明铜与根皮细胞壁的结合可能有助于铜的毒性作用。当暴露于锌时，皮质浓度保持相对较低，大部分锌在分生组织区域积累并进入石柱；约60%至85%的总锌在暴露3小时内以植酸锌的形式储存。虽然镍在皮层和分生组织中的浓度都很高，但在石柱中的浓度相对较低。据我们所知，这是关于Cu， Ni和Zn在水合（和新鲜）植物组织中的原位分布和形态的第一份报告，为它们毒性的潜在机制提供了有价值的信息。
The phytotoxicity of trace metals is of global concern due to contamination of the landscape by human activities. Using synchrotron-based x-ray fluorescence microscopy and x-ray absorption spectroscopy, the distribution and speciation of copper (Cu), nickel (Ni), and zinc (Zn) was examined in situ using hydrated roots of cowpea (Vigna unguiculata) exposed to 1.5 mu M Cu, 5 mu M Ni, or 40 mu M Zn for 1 to 24 h. After 24 h of exposure, most Cu was bound to polygalacturonic acid of the rhizodermis and outer cortex, suggesting that binding of Cu to walls of cells in the rhizodermis possibly contributes to the toxic effects of Cu. When exposed to Zn, cortical concentrations remained comparatively low with much of the Zn accumulating in the meristematic region and moving into the stele; approximately 60% to 85% of the total Zn stored as Zn phytate within 3 h of exposure. While Ni concentrations were high in both the cortex and meristem, concentrations in the stele were comparatively low. To our knowledge, this is the first report of the in situ distribution and speciation of Cu, Ni, and Zn in hydrated (and fresh) plant tissues, providing valuable information on the potential mechanisms by which they are toxic.