Green‐Synthesized CuO Nanoparticles Combat Tobacco Bacterial Wilt via Pathogen Inhibition, Motility Impairment and Metabolic Dysregulation in Ralstonia solanacearum

ABSTRACT

The development of a safe and efficient nano‐enabled strategy for managing tobacco bacterial wilt, a devastating agricultural bacterial disease caused by Ralstonia solanacearum , has attracted considerable research interest. Herein, green and environmentally friendly CuONPs were biosynthesized using orange peel extract and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X‐ray photoelectron spectroscopy (XPS). Notably, antibacterial assays revealed that CuONPs at 500 μg/mL exerted an inhibitory effect exceeding 90% against R. solanacearum . Further mechanistic investigations demonstrated that green‐synthesized CuONPs disrupt the structural integrity of the bacterial cell envelope, as confirmed by SEM imaging. In addition, swimming motility assays, twitching motility assays and transcriptomic analysis indicated that CuONPs impair multiple essential physiological processes in R. solanacearum , including locomotion, taxis, chemotaxis, protein synthesis, respiratory function and amino acid metabolism. These disruptions cause severe cellular damage or death, supporting the antibacterial activity against tobacco bacterial wilt. Importantly, CuONPs at 500 μg/mL showed excellent disease‐suppressing efficacy and promoted tobacco plant growth. Field trials confirmed that CuONPs achieved the highest disease control efficiency among all treatments. The disease index in the untreated control group was 41.08%, while CuONPs reduced it to 11.08%, representing a statistically significant improvement. Collectively, this study establishes an effective nano‐enabled strategy for managing tobacco bacterial wilt, clarifies the molecular and physiological mechanisms of CuONP‐mediated inhibition of R. solanacearum , and provides a theoretical basis for the practical application of CuONPs against this destructive phytopathogen.