Green Synthesis of Silver Nanozymes for Synergistic Antifungal Application on Crops

Fusarium pseudograminearum (Fpg) is a highly destructive fungal pathogen responsible for Fusarium crown rot (FCR) in wheat, leading to substantial yield losses and quality degradation. Silver nanoparticles (AgNPs), widely known for their potent antimicrobial properties, are increasingly considered viable alternatives to conventional fungicides. However, the antifungal efficacy and underlying mechanisms of AgNP as nanozymes against Fpg in wheat have been insufficiently explored. In this study, Ag-based nanozymes were successfully synthesized via a green route using Ocimum basilicum L. leaf extract as a reducing agent and denoted as AgNZs-g. The resulting AgNZs-g exhibited excellent dispersion stability in water and demonstrated a peroxidase (POD)-like activity. They showed significant antifungal effects against both the mycelia and spores of Fpg. Mechanistic investigations revealed that AgNZs-g induced intracellular reactive oxygen species (ROS) accumulation due to their POD-like activity and downregulated genes involved in phospholipid biosynthesis, thereby compromising fungal cell membrane integrity and inhibiting growth. Indoor pot experiments further confirmed that AgNZs-g effectively controlled FCR in wheat without adversely affecting seedling growth at the tested concentrations. Additionally, the combined application of AgNZs-g with tebuconazole significantly enhanced antifungal efficacy while reducing pesticide usage, thus mitigating the risk of resistance development. These findings suggest that AgNZs-g holds great potential as a standalone antifungal agent or in combination with chemical fungicides for the sustainable management of FCR in wheat.