Selenium (Se) is an indispensable trace element for humans and other animals. Various studies have demonstrated the beneficial effects of Se on plants, including the promotion of growth, accumulation of secondary metabolites, and enhancement of antioxidant capacity, thereby improving plant stress resistance. Consequently, Se biofortification has emerged as an effective strategy to elevate Se content and nutritional quality in plants, attracting widespread attention. The mechanism of selenium (Se) at the plant secondary metabolic level has not y...