Kamal Mohab Amin, Perveen Kahkashan, Khan Faheema, Sayyed R Z, Hock Ong Ghim, Bhatt Santosh Chandra, Singh Jyoti, Qamar Mohd Obaid
Department of Civil Engineering, College of Engineering, King Saud University, Riyadh, Saudi Arabia.
Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia.
Front Microbiol. 2023 Aug 3;14:1228117. doi: 10.3389/fmicb.2023.1228117. eCollection 2023.
Heavy metal pollution of soil is a major concern due to its non-biodegradable nature, bioaccumulation, and persistence in the environment. To explore the probable function of EDTA in ameliorating heavy metal toxicity and achieve the sustainable development goal (SDG), L. seedlings were treated with different concentrations of EDTA (0, 1.0, 2.0, 3.0, and 4.0 mM Kg) in heavy metal-polluted soil. Plant samples were collected 60 days after sowing; photosynthetic pigments, HO, monoaldehyde (MDA), antioxidant enzymes, and ascorbic acid content, as well as plant biomass, were estimated in plants. Soil and plant samples were also examined for the concentrations of Cd, Cr, Pb, and Hg. Moreover, values of the phytoremediation factor were utilized to assess the accumulation capacity of heavy metals by under EDTA treatments. In the absence of EDTA, seedlings accrued heavy metals in their roots and shoots in a concentration-dependent manner. However, the highest biomass of plants (roots and shoots) was recorded with the application of 2 mM kg EDTA. Moreover, high levels (above 3 mM kg) of EDTA concentration have reduced the biomass of plants (roots and shoots), photosynthetic area, and chlorophyll content. The effect of EDTA levels on photosynthetic pigments (chlorophyll a and b) revealed that with an increment in EDTA concentration, accumulation of heavy metals was also increased in the plant, subsequently decreasing the chlorophyll a and b concentration in the plant. TLF was found to be in the order Pb> Hg> Zn> and >Ni, while TF was found to be in the order Hg>Zn>Ni>Pb, and the best dose was 3 mM kg EDTA for Hg and 4 mM kg for Pb, Ni, and Zn. Furthermore, hyperaccumulation of heavy metals enhanced the generation of hydrogen peroxide (HO), superoxide anions (O), and lipid peroxidation. It also interrupts mechanisms of the antioxidant defense system. Furthermore, heavy metal stress reduced plant growth, biomass, and chlorophyll (chl) content. These findings suggest that the exogenous addition of EDTA to the heavy metal-treated seedlings increases the bioavailability of heavy metals for phytoextraction and decreases heavy metal-induced oxidative injuries by restricting heavy metal uptake and components of their antioxidant defense systems.
土壤重金属污染因其不可生物降解的特性、生物累积性以及在环境中的持久性而成为一个主要问题。为了探究乙二胺四乙酸（EDTA）在减轻重金属毒性方面的可能作用并实现可持续发展目标（SDG），在重金属污染土壤中用不同浓度的EDTA（0、1.0、2.0、3.0和4.0 mM Kg）处理L.幼苗。播种60天后采集植物样本；测定植物中的光合色素、过氧化氢（HO）、丙二醛（MDA）、抗氧化酶、抗坏血酸含量以及植物生物量。还检测了土壤和植物样本中镉（Cd）、铬（Cr）、铅（Pb）和汞（Hg）的浓度。此外，利用植物修复因子的值来评估在EDTA处理下植物对重金属的积累能力。在没有EDTA的情况下，L.幼苗的根和茎以浓度依赖的方式积累重金属。然而，施用2 mM kg的EDTA时记录到植物（根和茎）的生物量最高。此外，高浓度（高于3 mM kg）的EDTA降低了植物（根和茎）的生物量、光合面积和叶绿素含量。EDTA水平对光合色素（叶绿素a和b）的影响表明，随着EDTA浓度的增加，植物中重金属的积累也增加，随后植物中叶绿素a和b的浓度降低。发现转运系数（TLF）的顺序为Pb>Hg>Zn>和>Ni，而转移系数（TF）的顺序为Hg>Zn>Ni>Pb，对于Hg最佳剂量为3 mM kg EDTA，对于Pb、Ni和Zn为4 mM kg。此外，重金属的超积累增强了过氧化氢（HO）、超氧阴离子（O）的产生以及脂质过氧化。它还干扰了抗氧化防御系统的机制。此外，重金属胁迫降低了植物生长、生物量和叶绿素（chl）含量。这些发现表明，向重金属处理的幼苗中外源添加EDTA可提高重金属的生物有效性以用于植物提取，并通过限制重金属吸收及其抗氧化防御系统的成分来减少重金属诱导的氧化损伤。
