Silica nanoparticles enhance resistance of Vitis vinifera to downy mildew

Silica nanoparticles (SiO2 NPs) are emerging as promising tools for sustainable plant disease management. While their ability to enhance disease resistance has been demonstrated in several crop species, their potential in grapevine (Vitis vinifera) remains poorly investigated. Downy mildew, caused by the oomycete pathogen Plasmopara viticola, is one of the most destructive grapevine diseases worldwide, constituting a major challenge to viticulture. This study evaluates the efficacy of SiO2 NPs in controlling P. viticola infection and investigates the underlying plant responses at the molecular level. Foliar application of SiO2 NPs significantly reduced P. viticola infection in grapevine under both controlled (leaf disc assay) and field conditions. In vitro assays showed that SiO2 NPs did not exert direct toxicity towards P. viticola, indicating that the observed protection is plant-mediated. Transcriptomic analysis of SiO2 NP-treated non-infected leaves revealed transient activation of defence-related genes associated with salicylic acid, jasmonic acid and ethylene signalling, secondary metabolism and transcriptional regulation. However, these transcriptional responses were markedly attenuated upon infection. Metabolite profiling of phytohormones and stilbenes showed no significant differences between SiO2 NP-treated and control plants, suggesting that enhanced resistance relies on other plant-derived mechanisms. SiO2 NPs effectively reduced downy mildew severity in grapevine, although the underlying transcriptional and metabolic changes responsible for this effect remain unidentified. This suggests that alternative, possibly non-transcriptional mechanisms contribute to the observed protection. Overall, these findings provide new insights into SiO2 NP-induced responses in grapevine and highlight their potential for sustainable disease management.