Biogenic synthesis of iron oxide nanoparticles via Skimmia laureola and their antibacterial efficacy against bacterial wilt pathogen Ralstonia solanacearum

Plant diseases are threat to global food security. The excessive use of agrochemicals is the leading cause of pesticides resistance and toxicity to beneficial life forms. The quest for innocuous and alternate antimicrobial agent is crucial in order to overcome the pathogen resistance and the birth of nanotech offers pledge to combat pathogenic organisms. In this study, a facile benign biogenic approach was adopted for the synthesis of biocompatible iron oxide nanoparticles (Fe₂O_3-NPs) via Skimmia laureola leaf extract and the synthesized nanoparticles were evaluated for their antibacterial efficacy against bacterial wilt pathogen Ralstonia solanacearum in vitro and in planta. Physico-chemical characterization of the synthesized nanoparticles was performed through UV-Visible spectroscopy, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, Energy Dispersive X-ray Spectroscopy and Scanning Electron Microscopy. The results revealed polydisperse nanoparticles in the size range of 56 nm to 350 nm. The culture media containing 6 mg/mL of Fe₂O_3-NPs dramatically inhibited the bacterial growth in vitro. Scanning electron microscopy revealed degenerative characteristics including degraded, shriveled and concentrated cell walls. Diseases severity was effectively reduced with 6% w/v of Fe₂O_3-NPs treated root zone in planta. Plant shoots, root length and fresh biomass were enhanced with Fe₂O_3-NPs treatments. The results indicated that the biosynthesized Fe₂O_3-NPs have the potential to control agriculturally important phytopathogen Ralstonia solanacearum in vitro and in planta.