Green nanoparticles-assisted dsRNA delivery enables effective control of pepper mottle virus in pepper

Pepper mottle virus (PepMoV) is a major pathogen that affects pepper (Capsicum spp.) crops, causing severe yield and quality losses worldwide. Moreover, the efficacy of conventional management strategies, including the use of chemical pesticides, resistant cultivars, and biological control, remains limited. RNA interference (RNAi) using double-stranded RNA (dsRNA) has emerged as a promising and eco-friendly strategy for controlling plant viruses. Thus, this study aimed to design and compare dsRNA targeting the helper component proteinase (HC-Pro) gene and coat protein (CP) genes in PepMoV to identify the most effective antiviral target. HC-Pro-specific dsRNA exhibited superior inhibitory activity. Moreover, to overcome the instability and poor cellular uptake of naked dsRNA, three eco-friendly nanocarriers were fabricated and complexed with dsRNA: quaternary ammonium chitosan (HACC), layered double hydroxide (LDH), and mesoporous silica nanoparticles (MSN). All dsRNA/nanoparticle (NP) complexes exhibited a nanoscale size and positive surface charge, facilitating uptake and systemic movement in plants. Contact angle analysis and Cy3-labeling experiments further confirmed enhanced leaf surface adhesion and cellular penetration. Plants treated with dsRNA/NP complexes demonstrated significantly stronger and more durable antiviral protection than those treated with naked dsRNA at 7, 14, and 21 days post-treatment. These findings highlight the potential of NP-mediated dsRNA delivery as a scalable and sustainable RNAi-based approach for managing PepMoV and other plant viruses in agricultural systems.