Silica nanoparticles as a nano-elicitor: Modulating tomato (Solanum lycopersicum L.) plants metabolism to suppress bacterial wilt

The use of nanotechnology to stimulate plants for the autonomous production of defense-related bioactive compounds offers a sustainable alternative to conventional pesticides. Here, we demonstrate that foliar-applied silica nanoparticles (SiO 2 NPs) act as a potent nano-elicitor that primes systemic immunity in tomato ( Solanum lycopersicum L.) plants challenged by Ralstonia solanacearum . SiO 2 NPs reduced disease severity by 28.0-43.9% and increased shoot and root biomass by 35.4% and 124.0%, respectively. Physiological analyses revealed rapid activation of lipoxygenase and peroxidase enzymes, accompanied by enhanced accumulation of lignin and soluble phenolics. Untargeted metabolomics showed early defense priming and immune modulation, with enrichment of phenylpropanoids, tyrosine derivatives, and lipid-derived signals. Pathway analysis indicated activation of α-linolenic acid metabolism, phenylpropanoid biosynthesis, and hormone signaling. SiO 2 NPs elevated jasmonic acids and salicylic acids while reducing abscisic acid, reflecting coordinated hormonal crosstalk. Notably, SiO 2 NPs also induced sustained gene-expression priming, significantly upregulating MAPK1 (3.1-fold at 24 hpi, 1.4-fold at 72 hpi), MAPK3 (3.9-fold at 24 hpi, 1.1-fold at 72 hpi), and WRKY53 (4.4-fold at 24 hpi, 1.7-fold at 72 hpi) relative to pathogen-only controls. Machine learning analysis revealed the central role of salicylic acid in defense and a potential synergy between auxin/glutathione pathways and immunity. Collectively, SiO 2 NPs represent a promising nano-elicitor strategy to enhance crop resilience through defense priming and endogenous metabolite production.