Glutathione Reductase in Heavy Metal Nanoparticle-Stressed Plants

Abstract

Heavy metal contamination in agricultural systems has become an escalating environmental issue, affecting plant health, crop productivity, and food safety. Elements such as Nickel (Ni) and cobalt (Co), while essential micronutrients in small quantities, become toxic at elevated concentrations commonly found in industrially polluted soils. In plants, excessive Co disrupt metabolic processes by generating reactive oxygen species (ROS), impairing photosynthesis, altering nutrient uptake, and damaging cellular structures. The emergence of cobalt and nickel nanoparticles (NPs) has further intensified interest in their environmental impact, as nanoscale materials exhibit unique physicochemical properties, including large surface area and reactivity. While these properties make Co NPs valuable in catalysis, electronics, and biomedical applications, they can also enhance phytotoxic effects through accelerated ROS production, disruption of membrane integrity, and interference with antioxidant enzymatic systems. In plants, exposure to these nanoparticles can result in chlorosis, reduced growth, particularly by inducing oxidative stress through the overproduction of reactive oxygen species (ROS). To combat this oxidative damage, plants rely on a robust antioxidant defence system. At the core of this system is Glutathione Reductase (GR) a crucial enzyme responsible for maintaining cellular redox homeostasis. GR functions by regenerating reduced glutathione (GSH) from its oxidized form (GSSG), thereby sustaining the glutathione pool needed to neutralize ROS and support various metabolic pathways under stress. Because of its central role in detoxification and stress tolerance, GR serves as a sensitive biomarker for evaluating the biochemical impact of environmental stressors, including heavy metals and nanoparticles responses. Understanding the interactions between CoNPs in plant systems is essential for evaluating their toxicity, developing safe application strategies.