Antifungal activity of mycogenic selenium nanoparticles conjugated with fungal nano chitosan against three important phytopathogenic fungi

The management of phytopathogenic fungal diseases in an ecofriendly way is an important agricultural challenge. This study evaluates the antifungal activity of mycogenic selenium nanoparticles (SeNPs), chitosan nanoparticles (NCT), and their composite against three phytopathogenic fungi: Alternaria alternata , Fusarium oxysporum and Fusarium verticilliodes . SeNPs were prepared by a previous biosynthesis method. Exposure to SeNPs altered fungal morphogenesis, significantly reducing biomass and sporulation. Transmission electron microscopy revealed SeNPs interactions with cell walls and damage to organelles, with intracellular SeNPs localization. Chitosan was produced from Rhizopus arrhizus yielding 0.52 g/L at 79.5% deacetylation. Fourier transform infrared and scanning electron microscopy characterized NCT and the SeNPs-NCT composite. SeNPs exhibited the strongest antifungal effects, completely inhibiting A. alternata and F. oxysporum growth at 12 ppm and F. verticilliodes at 25 ppm. NCT showed antifungal properties but lower efficacy, requiring 1000 ppm for complete inhibition. The SeNPs-NCT composite reduced activity versus SeNPs alone. This study demonstrates the antifungal potential of SeNPs and NCT against important plant pathogens. SeNPs interactions with fungal cells are also elucidated, providing insights into potential mechanisms of action such as cell wall embedment and organelle disruption.