Supplementation of Selenium and Its Nano on Crop Plant Tolerance and Physiological Responses: A Review

Abstract

Selenium is an essential micronutrient that enhanced plant growth and development in trace amounts. It also protects plants against different abiotic stresses by acting as an antioxidant or stimulator in a dose-dependent manner. Selenium can also enhance cellular functions like membrane stability, mineral nutrition homeostasis, antioxidant response, photosynthesis, and thus improve plant growth and development under metal/metalloid stress. Selenium uptake, translocation, and accumulation is crucial to achieving the inclusive benefits of selenium in plants. Plant growth is affected by various abiotic stresses, including water, temperature, light, salt, and heavy metals. Selenium is not an essential nutrient for plants also but plays an important role in alleviating the abiotic stresses suffered by plants. Selenium promotes the uptake of beneficial substances, maintains the stability of plasma membranes, and enhances the activity of various antioxidant enzymes, thus alleviating adverse effects in plants under abiotic stresses. Therefore, we discusses the absorption, translocation, and signaling of selenium in plants as well as proteomic and genomic investigations of selenium shortage and toxicity. Low concentrations of selenium can mitigate metal/metalloid toxicity in plants and improve tolerance in various ways. Selenium stimulates the biosynthesis of hormones for remodeling the root architecture that decreases metal uptake. Growth enhancing function of selenium has been reported in a number of studies, which is the outcome of improvement of various physiological features. Photosynthesis has been improved by selenium supplementation under metal/metalloid stress due to the prevention of pigment destruction, sustained enzymatic activity, improved stomatal function, and photosystem activity However, extra amounts of selenium can restrict metal uptake by roots and translocation to shoots, which is one of the vital stress tolerance mechanisms. Metal/metalloid toxicity decreases crop productivity and uptake of metal/metalloid through food chain causes health hazards. Modulating the antioxidant defense, system selenium mitigates oxidative stress of selenium that improving the yield
and quality of plants. However, excessive concentration of selenium exerts toxic effects on plants.