RNA based gene silencing modalities to control insect and fungal plant pests - Challenges and future prospects

Using exogenously introduced dsRNA molecules to induce RNA interference (RNAi) has emerged as an effective tool to control crop pests. RNAi can be employed to suppress the critical growth and developmental genes of targeted phytophagous pests at the post-transcriptional level to control their damaging effects on crop plants. The technology is eco-friendly with an in-built advantage of specific targeting, thus provides a safer alternative to non-targeted chemical pesticides. Over the last two decades, basic research in RNAi pathway, dsRNA delivery routes, its uptake, and systematic spread across genres has been extensively analyzed. This review focuses on key delivery strategies of dsRNA molecules, including host-induced gene silencing (HIGS), spray-induced gene silencing (SIGS), and virus-induced gene silencing (VIGS), their strengths and weaknesses, and efficiency against phytophagous insects and fungal pathogens. Further, several cellular, physiological, and environmental barriers that affect the efficacy of these delivery routes are also discussed. Finally, an overview of future research orientations to improve the effectiveness of these RNAi tools is also described.