Carbon Dots and mesoporous silica nanocomposites improve spray-induced gene silencing to suppress plant RNA and DNA viruses

The management of emerging plant viruses presents significant challenges for global agriculture, requiring innovative approaches beyond conventional control strategies. Traditional methods rely on cultural practices, vector management, and breeding for genetic resistance, and these approaches are often time-consuming and may have limited effectiveness against emerging viral strains. Spray-Induced Gene Silencing (SIGS), involving topical application of virus-derived double-stranded RNA (dsRNA) to trigger plant defense mechanisms, offers a promising alternative strategy. However, the application of SIGS faces challenges due to inefficient dsRNA uptake by the plant, among other issues. In this study, we developed and characterized nanocomposite formulations using carbon dots (CDs) and polyethylenimine-functionalized mesoporous silica nanoparticles (PMSNs) to enhance dsRNA delivery and stability for the control of turnip mosaic virus (TuMV) and beet curly top virus (BCTV), an RNA and a DNA virus, respectively, in Nicotiana benthamiana. Our results demonstrated that dsRNA delivery was significantly enhanced (up to 5-fold) when formulated with nanoparticles compared to naked dsRNA. For TuMV-infected plants, both nanocomposite formulations significantly reduced viral titers (by 13.5-fold for PMSNs and 17.3-fold for CDs) and maintained photosynthetic capacity similar to uninfected controls even at 66 days post-inoculation. Regarding BCTV, the nanocomposite treatments significantly delayed disease symptom appearance and reduced viral DNA accumulation by 8-28-fold compared to control plants. The enhanced antiviral efficacy observed with nanoparticle formulations correlates with improved dsRNA delivery and persistence in plant tissues, making the nanoparticle-based dsRNA delivery systems represent a viable approach for developing sustainable, environmentally friendly strategies to protect crops against economically important viral diseases.