Unlocking the Potential of Nanoparticles in Regulation of Antioxidant Defense in Medicinal Plants Under Abiotic Stress Conditions

Plants, due to their stationary nature, are frequently encountered by a combination of abiotic stresses like heavy metals, salinity, extreme temperatures, drought, UV radiation, ozone etc. Virtually all abiotic stresses trigger the overproduction of reactive oxygen species (ROS), which produces oxidative bursts and causes metabolic dysfunctions inside the cells. The synchronous action of antioxidants (enzymatic and non-enzymatic) nullifies the consequences of ROS in the plants. The application of nanoparticles (NPs) in medicinal plants has become a new area of interest as they possess unique physicochemical characteristics over the traditional phytohormones, nutrients, osmolytes, and amino acids. The NPs of silver (Ag), copper oxide (CuO), titanium dioxide (TiO2), zinc oxide (ZnO), and silicon dioxide (SiO2) can be applied to mitigate the negative impacts of abiotic stresses by eliciting morpho-physiological, biochemical, and molecular responses in plants. NPs application potentially activates the antioxidant defense system of plants by triggering the production of various antioxidants and compatible osmolytes. Presenting an overview of major abiotic stresses, this chapter mainly describes the mechanisms (physiological, biochemical, and molecular) of abiotic stress mitigation in medicinal plants via regulation of antioxidant defense system(s). This chapter is intended to provide possible innovative solutions to researchers to enhance medicinal plant production under abiotic stresses.