Department of Ecology and Environmental Sciences, School of Biological Sciences, University of Adelaide, Adelaide, 5005, South Australia, Australia.
Plant Physiol Biochem. 2021 May;162:730-736. doi: 10.1016/j.plaphy.2021.03.043. Epub 2021 Mar 23.
Food crops often accumulate heavy metals above the recommended limits. Cadmium (Cd) is particularly harmful in terms of its potential dangers to human health. The effects of nutrient status and cation competition on Cd uptake and distribution in barley were investigated to analyse the main route for Cd entry into the plants. Cd uptake into whole plants was measured by radiotracer studies and elemental analysis using environmentally relevant concentrations. The nutrient status of the plants was altered by growing them hydroponically in micronutrient-deficient conditions (-Fe, -Mn, or -Zn). Fe and Zn were found to have a large effect on the uptake of Cd both via deficiencies and by the competition for uptake. However, Mn was found to have no effect on the uptake of Cd either via deficiency or by the competition for uptake. This strongly suggests that the main route for Cd uptake into the roots is via Fe and Zn transporters. The inhibition of Cd influx only by FeII (but not by FeIII) suggests that Cd uptake into the root occurs through divalent cation transporters. Since Cd is a non-essential metal in plants, the transport characteristics were compared with those of an essential micronutrient, Ni. At the same external concentration, more than twice as much Cd was absorbed as Ni in all of the different nutrient conditions. Ni translocation to the shoot was much lower than for Cd. The comparison of two metals showed some similarities in the root uptake processes but not in the shoot translocation.
粮食作物常常积累重金属超过建议的限制。镉（Cd）在对人类健康的潜在危害方面尤其有害。本研究通过放射性示踪研究和使用环境相关浓度的元素分析，调查了营养状况和阳离子竞争对大麦中 Cd 吸收和分布的影响，以分析 Cd 进入植物的主要途径。通过水培在微量元素缺乏条件下（-Fe、-Mn 或-Zn）生长来改变植物的营养状况。发现 Fe 和 Zn 对 Cd 的吸收有很大的影响，无论是通过缺乏还是通过竞争吸收。然而，Mn 无论是通过缺乏还是通过竞争吸收，对 Cd 的吸收都没有影响。这强烈表明，Cd 进入根系的主要途径是通过 Fe 和 Zn 转运体。只有 FeII（而不是 FeIII）抑制 Cd 流入，表明 Cd 进入根部是通过二价阳离子转运体进行的。由于 Cd 是植物中的非必需金属，因此将其转运特性与必需微量元素 Ni 进行了比较。在相同的外部浓度下，在所有不同的营养条件下，Cd 的吸收量是 Ni 的两倍多。Ni 向地上部的转运远低于 Cd。两种金属的比较表明，根部吸收过程有一些相似之处，但地上部转运则没有。
