Silicon-mediated defense mechanisms in plants under heavy metal stress

Background The excessive accumulation of heavy metals in soil poses a significant threat to plant growth and productivity, with adverse consequences for the environment. This review provides a comprehensive synthesis of different sources of heavy metals toxicity and describes the oxidative stress caused by the reactive oxygen species under stress conditions. The differential response or selective interaction of heavy metals with plants affects the cell organelles and results in the growth reduction. Silicon (Si) is one such element that has been found to help reduce heavy metal poisoning. This review analyzes the mechanism underlying the protection through which Si mitigates metal toxicity. It also improves plant resilience by maintaining oxidative balance. Furthermore, this review examines the interaction of Si with plant hormonal signaling networks, including abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA). This contributes to understanding stress perception and signal transduction pathways in plants. Objectives and methods This article discusses the beneficial effects of silicon and how it can be considered as a promising ameliorative to fight stress caused by heavy metals. It is important to understand the absorption and transportation of silicon in plants. Results This review highlights how silicon interacts with different heavy metals, phytohormones and signaling molecule and in turn impacts osmolytes, oxidative stress, water status, photosynthesis and thereby acts as a plant growth regulator. With its non-toxic and cost effectiveness aided with technology and research, Si promises scope in field of agriculture remediation, phytoremediation and ecological restoration. Conclusions The future perspective focuses on integrating Si with emerging and existing technologies and to expand its application to various ecosystems and into the farmer’s field. It also focuses on detecting Si-responsive genes, and analyzing nano-silicon formulations for improved metal toxicity. In spite of augmenting indication that Si alleviates heavy metals toxicity, information is less how Si interacts with different metal ions, impacts phytohormonal regulation and controls stress signaling networks.