Exploring the Potential of Lecanicillium aphanocladii AUMC-16936 as a Novel Microbial Cell Factory for the Biosynthesis of CuONPs Against Potato Fusarium Wilt

Background Utilizing fungal metabolic processes for the eco-friendly synthesis of nanomaterials has arisen as a sustainable substitute for chemical manufacturing. To the best of our knowledge, this is the first report describing the mycosynthesis of bioactive CuONPs using Lecanicillium aphanocladii and evaluating their efficacy against potato Fusarium wilt. Results Herein, CuONPs were mycosynthesized utilizing the cell-free filtrate of L. aphanocladii AUMC-16936, acting as a bio-reductant and capping agent. UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), and X-ray spectroscopy (XRD) patterns confirmed the precise composition of the rod-shaped CuONPs with a mean particle size of 15.24 ± 4.19 nm. The biogenic CuONPs demonstrated potent antifungal activity in vitro against Fusarium oxysporum , with 100 ppm identified as the optimal inhibitory concentration. To validate the biological functionality of the synthesized particles, in vivo trials were conducted on potato plants. Foliar application of the mycosynthesized CuONPs (100 ppm) proved superior to soil watering, significantly mitigating Fusarium wilt severity. The treatment triggered a systemic defense response, evidenced by the upregulation of antioxidant enzymes as ascorbate peroxidase (APX), peroxidase (POD), and polyphenol oxidase (PPO), along with non-enzymatic indicators including total antioxidant capacity (TAC), total phenolic content, ascorbic acid, as well as glutathione, leading to a marked reduction in oxidative stress markers (H ₂ O ₂ , MDA). Moreover, elevated expression levels of several regulatory defense genes, such as PR-1b , IbBBx24 , and CHI , were noted in all plants that have been treated in comparison to infected ones. Conclusions L. aphanocladii AUMC-16936 efficiently yields bioactive CuONPs that combat Fusarium wilt in potato plants offering a promising strategy for sustainable nano-fungicides.