Thyme essential oil-based nano-fungicide for managing Fusarium wilt in Anoectochilus roxburghii

This study develops a thyme essential oil (TEO)-based bio-fungicide, encapsulated in amino-functionalized mesoporous silica nanoparticles (AMSNs), and evaluates its antifungal efficacy. In vitro, the TEO@AMSNs formulation demonstrated 93.23 % mycelial growth inhibition at 3.84 mg/mL, outperformed free TEO (67.77 % inhibition), with a 13.44 % loading rate. Mechanistic studies indicated that this efficacy results from continuous and strong membrane disruption and high reactive oxygen species (ROS) overaccumulation in fungal cells. Density functional theory (DFT) calculations confirmed that the stable release profiles was driven by hydrogen bonding interactions between the AMSNs carrier and the essential oil. In vivo trials on Anoectochilus roxburghii (A. roxburghii), a medicinal crop susceptible to F. oxysporum, showed that TEO@AMSNs significantly reduced disease symptoms and promoted root development. Inoculated plants treated with TEO@AMSNs at 2 MIC exhibited nearly normal lateral root counts (∼42) compared to 23 in untreated controls. Microscopic analyses revealed intact chloroplasts and preserved polysaccharide levels in treated plants, suggesting reduced oxidative stress and metabolic disruption. Flavonoid accumulation was also enhanced, further supporting the formulation's role in mitigating pathogen-induced stress. These findings highlight TEO@AMSNs as a promising, sustainable bio-fungicide for managing Fusarium infections and enhancing crop resilience.