Silver nanoparticles as a multifunctional nanotechnology for green control of fungal stress and microplastic-associated heavy metal toxicity in soybean

In this study, silver nanoparticles (Ag-NPs) were evaluated as a multifunctional nanotechnological material for mitigating stress induced by microplastics (MPs), a persistent form of biological contaminant, and fungal pathogens ( Colletotrichum brevisporum causing anthracnose and Fusarium oxysporum causing root rot) within a soybean. Ag-NPs exhibited strong antifungal activity, suppressing mycelial growth of C. brevisporum by 73% at 90 μg mL −1 and F. oxysporum by 56% at 60 μg mL −1 , resulting in reduced disease incidence of 54% and 61%, respectively, and improved photosynthetic performance. Beyond direct pathogen inhibition, Ag-NPs activated nanoscale defense responses by enhancing antioxidant enzyme activities, inducing defense-related gene expression, and promoting callose deposition, thereby alleviating oxidative stress as evidenced by reduced malondialdehyde and hydrogen peroxide levels. Ag-NPs treatment also improved seed germination and root biomass, counteracting the detrimental effects of combined MP and pathogen stress. Importantly, Ag-NPs significantly reduced heavy metal accumulation in soil, roots, and leaves, whereas MP exposure alone or in combination with fungal infection markedly increased heavy metal uptake in soybean. While fungal infection alone had minimal influence on metal accumulation, MPs substantially exacerbated heavy metal toxicity within the soybean. Overall, the present study demonstrates that Ag-NPs function as a dual-purpose nanomaterial capable of simultaneously suppressing phytopathogens and mitigating biological contaminant-associated metal stress. These findings provide mechanistic insight into nano-enabled environmental protection and highlight the potential of Ag-NPs as a materials-based strategy for enhancing resilience in contaminated plant-soil systems which have soybean crops.