Mycogenic synthesis of silver nanoparticles using endophytic fungi and their characterization, biological activities, including in-silico studies with special reference to Fusarium wilt of tomato

Abstract

Nanoparticle research is currently a topic of significant scientific interest, due to its vast array of application in biological field. An effort was made to produce silver nanoparticles (AgNPs) from two endophytic fungi; Fusarium oxysporum (FoAgNPs) and Fusarium proliferatum (FpAgNPs), which were isolated from a Pteridophyte Pyrrosia lanceolata (L.) Farw. The AgNPs were characterised using UV-Vis spectroscopy, exhibiting sizes ranging from 3 nm to 27 nm and displaying a polycrystalline nature as determined by scanning and transmission microscopy, along with SAED pattern analysis. Additionally, we identify phenolic groups at 1067.12 cm^-1 as the capping agent that facilitates the reduction of silver ions and stabilizes the nanoparticles evaluated via FTIR. The in vitro antibacterial potency AgNPs had the maximum activity against Escherichia fergusonii, followed by Proteus mirabilis; for both organisms, the minimum inhibitory concentration (MIC) value was 10 μg/ml. AgNPs also demonstrated strong antifungal activity against various plant pathogens, MIC was 15 μg/ml. Additionally, SEM analysis revealed that AgNPs caused pathogen hypha shrinkage and deformation, indicating structural deterioration in cellular and organelle structures due to ROS production. Further, the antifungal efficacy of manufactured AgNPs was investigated against F. oxysporum f.sp. lycopersici in Solanum lycopersicum, a plant pathogen affecting tomato growth and yield, and nano-formulation (150 ppm) completely prevented infection in the greenhouse settings. Biogenic AgNPs at 40 ppm enhanced root-shoot length in Vigna radiata seeds compared to untreated seeds, suggesting phyto-stimulatory action. The cytotoxicity assessment indicated that the synthesized AgNPs are safe for a variety of bio-applications. Furthermore, we chose NADPH Oxidase (F. oxysporum f.sp. lycopersici) as the protein to perform the molecular docking and results indicates that the active site of the selected protein serves as a critical region for inhibiting disease propagation. The study findings enhanced our knowledge of the antifungal properties and mechanisms of AgNPs, providing a novel perspective on utilising this antifungal alternative for the treatment of plant diseases.

Keywords: Endophytic fungi; Fusarium wilt of tomato; Mycosynthesis; ROS; Silvernanoparticles.