Characterization and disease control potential of biogenic silver nanoparticles against angular leaf spot of cucurbits

The present study focused on the biogenic formation of nanoparticles using leaf extract of Lantana camara L. The phytochemical analysis of leaf extract revealed the presence of several bioactive compounds such as alkaloids, flavonoids, saponins, tannins, resin and oils. The synthesis of biogenic nanoparticles was confirmed through various characterization techniques viz. UV–Vis spectroscopy (Ultraviolet–visible spectroscopy), FTIR analysis (Fourier-transform infrared spectroscopy), SEM(Scanning Electron Microscope), EDS (Energy-dispersive X-ray spectroscopy) and XRD (X-ray diffraction) for their optical properties, functional group, morphological, elemental composition and structural properties, respectively. Further, the antibacterial activity of characterized biogenic nanoparticles revealed inhibition zones of 18.17 ± 0.17, 19.33 ± 0.17 and 20.17 ± 0.33 (mm) at various concentrations 150, 185 and 200 µg/mL respectively against Pseudomonas syringae (MTCC-7620).The MIC value of biosynthesized nanoparticles was recorded at 80 µg/mL and MBC value was found to be 160 µg/mL, indicating strong bactericidal efficacy.The flow cytometric phytotoxicity data indicated a clear concentration-dependent cytotoxic effect of the nanoparticles. Additionally, the pathogenicity of the bacterial strain was assessed in the pot experiments on Luffa cylindrica plants (sponge gourd), where the characteristic symptoms appeared following inoculation. The biogenic nanoparticles were foliar applied through both the methods i.e. pre-treatment as well as post-inoculation treatments. It was observed that post-inoculation treatment (75 ppm) had a higher reduction in disease severity (37.50%) as compared to pre-treatments (33.33%). Experimentally, 0.5% copper oxychloride as a pre-treatment and 1.5% as a post inoculation-treatment demonstrated 29.17% and 41.67% PDI respectively. These findings underscore the potential of L. camara L leaf extract-mediated nanoparticles as effective antibacterial agents, offering new prospects alternatives to conventional bactericides.