Green-synthesized iron oxide nanoparticles for bacterial wilt control: Comprehensive mechanistic and efficacy insights

Abstract

Importance of the Work: Bacterial wilt, caused by Ralstonia solanacearum (International
Society for Plant Pathology; www.isppweb.org) is a devastating plant disease that is difficult
to control with conventional methods. Green-synthesized iron oxide nanoparticles (IONPs) offer
a sustainable, eco-friendly and biocompatible alternative. Their biogenic production uses natural
extracts, reduces toxic inputs and energy consumption, and provides strong antibacterial activity.
Objectives: To review the biogenic synthesis of IONPs from plant and microbial sources, and to
evaluate their mechanisms, characterization and potential for bacterial wilt control.
Materials and Methods: The synthesis process involved three stages: reduction of metal salts
by biomolecules, nucleation and growth into nanoscale clusters, and stabilization/capping
to prevent aggregation. Characterization of these IONPs was performed using a suite of
techniques: ultraviolet-visible Spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy
(FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron
microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Dynamic light scattering
(DLS) and atomic force spectroscopy (AFM).
Results: The reviewed studies showed that green-synthesized IONPs exhibited strong
antibacterial efficacy against R. solanacearum both in vitro and in greenhouse trials. In tomato
plants, root-zone treatments and foliar applications significantly reduced disease incidence
dropping as low as 13.09% compared to 98.01% in untreated controls in some reports.
Furthermore, IONPs improved plant growth parameters, including biomass, shoot length and
chlorophyll content, while enhancing soil health through increased enzyme activity and nutrient
availability.
Main Findings: The primary finding was that IONPs combat bacterial wilt through
a multifaceted mechanism involving: disrupting bacterial cell membranes via electrostatic
interactions; generating reactive oxygen species that damage DNA and proteins; and inhibiting
the formation of protective biofilms by interfering with quorum sensing. These findings suggest
that integrating IONPs into disease management strategies could substantially reduce reliance
on chemical pesticides and enhance agricultural resilience.