Department of European and Mediterranean Cultures: Architecture, Environment and Cultural Heritage (DiCEM), University of Basilicata, Via Lanera, 20, 75100, Matera, Italy.
Plant Physiology and Biochemistry Laboratory, Department of Botany, Aligarh Muslim University, Aligarh, 202002, India.
Plant Physiol Biochem. 2022 Jan 15;173:68-75. doi: 10.1016/j.plaphy.2022.01.027. Epub 2022 Jan 26.
Contamination of soil by heavy metals severely affects plant growth and causes soil pollution. While effects on plant growth have been investigated for metals taken individually or in groups, less is known about their comparative effects. In this study Arabidopsis thaliana seedlings were grown for 14 days in Petri dishes containing medium contaminated by six common heavy metals (Hg, Cd, Pb, Cu, Ni and Zn), at the minimum concentrations defined as toxic by the most recent EU legislation on contamination of agricultural soils. (a) Root structure and morphology, (b) metal composition and translocation, and (c) the levels of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) were analyzed. Metals accumulated more in roots than in shoots, with concentrations that differed by several orders of magnitude depending on the metal: Cd (ca. 700 × and ca. 450 × in roots and shoots, respectively), Hg (150 × , 80 × ), Ni (50 × , 20 × ), Cu (48 × , 20 × ), Zn (23 × , 6 × ), and Pb (9 × , 4 × ). Responses were significant for at least nine of the ten root parameters (with the exception of Hg), and five of the six shoot parameters (with the exception of Zn). Cu and Zn induced respectively the strongest responses in root hormonal (up to ca. 240% the control values for IBA, 190% for IAA) and structural parameters (up to 210% for main root length, 330% for total lateral root length, 220% for number of root tips, 600% for total root surface, and from 2.5° to 26.0° of root growth angle). Regarding the shoots, the largest changes occurred for shoot height (down to 60% for Ni), rosette diameter (down to 45% for Hg), leaf number (up to 230% for Zn) and IBA (up to 240% for Pb and Cu). A microscope analysis revealed that shape and conformation of root hairs were strongly inhibited after Cd exposure, and enhanced under Hg and Pb. The results could have positive applications such as for defining toxicity thresholds (in phytoremediation) and acceptable concentration levels (for policies) for some of the most common heavy metals in agricultural soils.
重金属污染土壤严重影响植物生长并导致土壤污染。虽然已经研究了单独或分组的金属对植物生长的影响，但对它们的比较影响知之甚少。在这项研究中，将拟南芥幼苗在含有六种常见重金属（汞、镉、铅、铜、镍和锌）污染的培养基的培养皿中培养 14 天，这些重金属的浓度是根据欧盟最新的农业土壤污染法规确定的毒性最低浓度。（a）分析根结构和形态，（b）金属组成和迁移，以及（c）吲哚-3-乙酸（IAA）和吲哚-3-丁酸（IBA）的水平。金属在根部的积累量多于在地上部分，浓度差异可达几个数量级，具体取决于金属：镉（分别约为 700×和 450×在根部和地上部分）、汞（150×，80×）、镍（50×，20×）、铜（48×，20×）、锌（23×，6×）和铅（9×，4×）。至少有 10 个根参数（汞除外）和 6 个地上参数（锌除外）的反应具有统计学意义。铜和锌分别诱导根激素（IBA 最高可达对照值的 240%，IAA 最高可达 190%）和结构参数（主根长度最高可达 210%，总侧根长度最高可达 330%，根尖数最高可达 220%，总根表面积最高可达 600%，根生长角度从 2.5°增加到 26.0°）的最强反应。关于地上部分，变化最大的是地上部分的高度（镍降至 60%）、莲座丛直径（汞降至 45%）、叶数（锌增至 230%）和 IBA（铅和铜增至 240%）。显微镜分析显示，镉暴露后根毛的形状和形态受到强烈抑制，而在汞和铅下则增强。这些结果可能具有积极的应用，例如定义某些农业土壤中最常见的重金属的毒性阈值（在植物修复中）和可接受浓度水平（用于政策）。
