Gulzar Abu Barkat Md, Mazumder Pranab Behari
Plant & Microbial Molecular Biology Laboratory, Department of Biotechnology, Assam University, Silchar, India.
Environ Sci Pollut Res Int. 2022 Jun;29(27):40319-40341. doi: 10.1007/s11356-022-19756-0. Epub 2022 Mar 22.
Heavy metals (HMs) are not destroyable or degradable and persist in the environment for a long duration. Thus, eliminating and counteracting the HMs pollution of the soil environment is an urgent task to develop a safe and sustainable environment. Plants are in close contact with the soil and can play an important role in soil clean-up, and the process is known as phytoremediation. However, under HM contaminated conditions, plants suffer from several complications, like nutrient and mineral deficiencies, alteration of various physiological and biological processes, which reduces the plant's growth rate. On the other hand, the bioavailability of HMs is another factor for reduced phytoremediation, as most of the HMs are not bioavailable to plants for efficient phytoremediation. The altered plant growth and reduced bioavailability of HMs could be overcome and enhance the phytoremediation efficiency by incorporating either nanotechnology, i.e., nanoparticles (NPs) or plant growth promoting rhizobacteria (PGPR) along with phytoremediation. Single incorporation of NPs and PGPR might improve the growth rate in plants by enhancing nutrient availability and uptake and also by regulating plant growth regulators under HM contaminated conditions. However, there are certain limitations, like a high dose of NPs that might have toxic effects on plants. Thus, the combination of two techniques such as PGPR and NPs-based remediation can conquer the limitations of individual techniques and consequently enhance phytoremediation efficiency. Considering the negative impacts of HMs on the environment and living organisms, this review is aimed at highlighting the concept of phytoremediation, the single or combined integration of NPs and PGPR to help plants deal with HMs and their basic mechanisms involved in the process of phytoremediation. Additionally, the complications of using NPs and PGPR in the phytoremediation process are discussed to determine future research questions and this will assist to stimulate further research in this field and increase its effectiveness in practical application.
重金属（HMs）不可破坏或降解，会在环境中长期存在。因此，消除和应对土壤环境中的重金属污染是发展安全、可持续环境的一项紧迫任务。植物与土壤密切接触，在土壤净化中可发挥重要作用，这一过程被称为植物修复。然而，在重金属污染条件下，植物会出现多种问题，如养分和矿物质缺乏、各种生理和生物过程改变，这会降低植物的生长速度。另一方面，重金属的生物有效性是植物修复效率降低的另一个因素，因为大多数重金属对植物而言无法有效用于植物修复。通过将纳米技术（即纳米颗粒（NPs））或植物促生根际细菌（PGPR）与植物修复相结合，可以克服植物生长改变和重金属生物有效性降低的问题，提高植物修复效率。单独使用纳米颗粒和植物促生根际细菌可能通过提高养分有效性和吸收，以及在重金属污染条件下调节植物生长调节剂来提高植物的生长速度。然而，存在一些局限性，比如高剂量的纳米颗粒可能对植物产生毒性作用。因此，植物促生根际细菌和基于纳米颗粒的修复等两种技术的结合可以克服个别技术的局限性，从而提高植物修复效率。考虑到重金属对环境和生物体的负面影响，本综述旨在突出植物修复的概念、纳米颗粒和植物促生根际细菌的单一或联合整合，以帮助植物应对重金属及其在植物修复过程中涉及的基本机制。此外，还讨论了在植物修复过程中使用纳米颗粒和植物促生根际细菌的复杂性问题，以确定未来的研究问题，这将有助于推动该领域的进一步研究，并提高其在实际应用中的有效性。
