Department of Plant Physiology and Molecular Plant Biology, Eötvös University, Pázmány P. sétány 1/C, Budapest 1117, Hungary.
Plant Physiol Biochem. 2011 May;49(5):494-8. doi: 10.1016/j.plaphy.2011.01.011. Epub 2011 Jan 19.
In plants, Cd causes perturbation of root metal uptake and is known to interfere with the metal translocation to the shoot. The most significant effect is the strongly reduced transport of Fe. Fe accumulation in roots under Cd stress revealed that it is not the Fe acquisition but the Fe loading to xylem elements that is blocked by Cd, which can be a result of competition between Fe and Cd for the transporters. However, in animal cells as well as in plant stomata guard cells, Cd was shown to move through Ca channels. To clarify whether the perturbation of metal translocation/xylem loading caused by Cd show any regularity, translocation ability was tested by the determination of the metal content in leaves of hydroponically cultured (¼ Hoagland nutrient solution, Fe source: 10 μM Fe((III))-citrate) poplar plants grown for three weeks with or without 10 μM Cd(NO₃)₂ treatment. Metals could be classified into two groups according to the behavior of their translocation under Cd treatment: alkaline earth metals (except Mg), Zn and Mn were influenced similarly to Ca, but other transition metals (together with alkali metals and Al) behaved like the Fe. Based on the translocation pattern, Cd seems to inhibit the transport of Ca-like metals competitively, but a different type of inhibition is exerted on the transition metal transport, with which Cd can share a common translocation system. The strongly decreased translocation of chelator-dependent transition metals may indicate Cd related disturbances in signalling pathways and gene expression of xylem transporters or chelators.
在植物中，Cd 会引起根系金属吸收的紊乱，已知会干扰金属向地上部分的转运。最显著的影响是强烈减少了 Fe 的运输。在 Cd 胁迫下，根中 Fe 的积累表明，被 Cd 阻断的不是 Fe 的获取，而是 Fe 向木质部元素的加载，这可能是 Fe 和 Cd 对转运体竞争的结果。然而，在动物细胞以及植物保卫细胞中，Cd 被证明可以通过 Ca 通道移动。为了澄清 Cd 引起的金属转运/木质部加载的紊乱是否表现出任何规律性，通过测定在水培培养（¼ Hoagland 营养液，Fe 源：10 μM Fe((III))-柠檬酸盐）的杨树叶片中的金属含量来测试转运能力，这些杨树在有或没有 10 μM Cd(NO₃)₂处理的情况下生长了三周。根据 Cd 处理下的转运行为，金属可以分为两组：碱土金属（除了 Mg）、Zn 和 Mn 与 Ca 相似受到影响，但其他过渡金属（与碱金属和 Al 一起）的行为与 Fe 相似。基于转运模式，Cd 似乎竞争性地抑制类似 Ca 的金属的运输，但对过渡金属的运输施加了不同类型的抑制，Cd 可以与该系统共用。螯合剂依赖性过渡金属的强烈减少的转运可能表明 Cd 相关的木质部转运体或螯合剂的信号通路和基因表达的干扰。
