Selenium nanoparticles enhance plant tolerance to salinity and protect from postharvest fungal infection

Nanotechnology is an emerging alternative to conventional phytochemicals for improving crop productivity and maintaining the postharvest fruit quality sustainably. In this work, selenium nanoparticles (SeNPs) were synthesized by reduction of sodium selenite with ascorbic acid and stabilized with the natural polysaccharide dextrin. These SeNPs averaged 27 nm in diameter and featured an amorphous structure, exhibiting a high antioxidant capacity at ≥ 10 mg L −1 , and effective scavenging activity for reactive oxygen species (hydroxyl radical and hydrogen peroxide) at concentrations as low as 1 mg L −1 . Applied to seedlings of edible leaf plant (lettuce), these SeNPs enhanced plant growth, particularly root growth, and salinity tolerance, being 5 mg L −1 the optimum concentration. The SeNPs also showed antifungal activity against Botrytis cinerea , the main causal agent of gray mold in postharvest fruits: in vitro, SeNPs at 1 mg L −1 caused a complete growth inhibition of B. cinerea, while in vivo , SeNPs at 10 mg L −1 proved effective in preventing gray mold on grapes, raspberries and strawberries. As selenium could be incorporated into edible parts of the plant, and due to the interest in selenium fortification, the toxicity of SeNPs in humans was checked using Caenorhabditis elegans as a model system. Their low toxicity in this animal model, together with the positive effect on seedlings growth and salinity tolerance, and postharvest antifungal activity, lay the foundation for future research in the implementation of these SeNPs in the agri-food industry. • The SeNPs have scavenging ability against different free radicals. • The SeNPs possess a high antioxidant capacity. • SeNPs promote plant growth and improve tolerance to salinity stress. • SeNPs inhibit infection caused by Botrytis cinerea. • The use of the Caenorhabditis elegans animal model confirms the low toxicity of SeNPs.