Nanoparticle-mediated mitigation of salt stress-induced oxidative damage in plants: insights into signaling, gene expression, and antioxidant mechanisms

Abstract

Salt stress presents a major challenge to global agriculture, leading to decreased crop yields, diminished food quality, economic losses, and threats to food security. Elevated salinity levels enhance the production of reactive oxygen species (ROS), such as superoxide anions (O₂˙⁻), hydrogen peroxide (H₂O₂), hydroxyl radicals (˙OH), and singlet oxygen (¹O₂). These ROS can inflict severe damage on cellular components, including proteins, lipids, carbohydrates, and DNA. Although plants have innate antioxidant defenses to mitigate ROS effects, these defenses often fall short under salinity stress, leading to oxidative damage, stunted growth, and diminished productivity. Recent research highlights the potential of nanoparticles (NPs) to enhance plant resilience against salinity-induced oxidative stress. Various types of NPs, metal oxide nanoparticles (e.g., Fe₂O₃, TiO₂, ZnO, CeO₂), silicon-based nanoparticles (e.g., Si NPs, SiO₂ NPs), noble metal nanoparticles (e.g., Ag, Au–Ag alloy NPs), carbon-based nanoparticles (e.g., graphene oxide, carbon NPs), chitosan NPs, and composite/functionalized NPs (e.g., polyacrylic acid coated nanoceria, calcium–silicon NPs, selenium–chitosan NPs) can enhance plant resilience to salinity-induced oxidative stress. They enter plants through leaves, roots, or seeds. Once within plant cells, these NPs can act as direct scavengers of ROS or modulate the antioxidant defense system. They affect signaling ions such as calcium, signaling molecules like nitric oxide (NO) and phytohormones, and regulatory factors like transcription factors (TFs), thereby regulating gene expression and production of antioxidant enzymes. Moreover, NPs can enhance the accumulation of non-enzymatic antioxidant compounds, such as ascorbate (AsA) and glutathione (GSH), further strengthening a plant's ability to withstand oxidative stress. As research advances, understanding the full potential of NPs to mitigate salt stress and enhance agricultural sustainability is crucial. However, the long-term environmental impacts of NPs must also be carefully evaluated to ensure their safe and sustainable use.