Multifaceted role of selenium in plant physiology and stress resilience: A review

Selenium (Se) is a naturally occurring element in both seleniferous and non-seleniferous soils. Plants absorb Se in a variety of ways, mainly as selenate (SeO₄^2-), selenite (SeO₃^2-), and organic compounds such as selenomethionine (SeMet). Selenium significantly impacts plant growth, development, and stress responses. It is a trace element that regulates many physiological and biochemical functions in plants, acts as an antioxidant, and increases plant resistance to abiotic stresses such as heavy metal toxicity, salinity, drought, and severe temperatures. Its beneficial effects depend on the dose and vary depending on the plant species and the environmental conditions. Several functions of Se have been thoroughly discussed in this review, with special attention given to the mechanisms of Se uptake, transport, accumulation, and metabolism. Plants use Se through its assimilation into amino acids (mostly selenocysteine and selenomethionine) and integration into proteins. These processes might have different effects depending on the Se concentration. Furthermore, Se has the potential to be a useful tool in sustainable agriculture, especially in regions where environmental stress is common. This is demonstrated by its ability to increase plant tolerance to various environmental stressors. Recent research shows that Se supplementation not only boosts plant resistance but also enhances secondary metabolite accumulation. Overall, this review concludes that Se plays a dual role in plant systems, acting as both a nutrient and a stress mitigator, and provides opportunities to optimize its use in sustainable agriculture by tailoring Se supplementation to maximize plant tolerance and productivity.