Selenium phytofortification: enhanced stress resistance and nutraceutical enrichment in horticultural crops.

As a bridge between human health and plant nutrition, Selenium (Se) phytofortification represents a promising strategy for achieving a safe and effective dietary Se supplementation. Due to chemical similarities, Se absorption, transformation, and storage in crops primarily follow the sulfur metabolic pathway. Se enhances horticultural crop resilience against abiotic and biotic stresses by: (i) boosting antioxidant capacity, (ii) inducing hormonal cascades, (iii) promoting the accumulation of key metabolites (e.g. amino acids, flavonoids), (iv) strengthening cellular functions, and (v) harnessing plant-microbiome interactions. In horticultural crops, most Se exists in organic forms, such as selenoamino acids, selenoproteins, selenium-polysaccharides, and selenium-polyphenols, which contribute to unique quality traits. Additionally, Se regulates the synthesis of core nutrients, including amino acids, flavonoids, phenolic compounds, soluble sugars, mineral elements, alkaloids, and volatile compounds. It also extends postharvest shelf life by delaying senescence and deterioration. Current phytofortification strategies focus on enhancing bioavailable Se in edible parts through agronomic interventions and plant breeding. Artificial Se fertilization is the most common agronomic approach, classified by the application method (soil fertilization, foliar spraying, hydroponic supplementation, and seed soaking) and fertilizer type (inorganic, organic, nano-Se, and biosynthesized fertilizers). Optimizing plant species, fertilization methods, dosage, timing, and elemental synergies maximize phytofortification efficiency.