Envisaging the role of plant Small RNAs: A comprehensive review on antiviral defense mechanisms.

Plant viruses continue to impose severe constraints on global agriculture, often leading to substantial yield and economic losses. Conventional management strategies such as vector control and resistance breeding frequently fail to provide durable and broad-spectrum protection due to rapid evolution of virus, their dependence on host cellular machinery and the lack of effective antiviral compounds. These shortcomings have led researchers to increasingly explore molecular approaches, with RNA interference (RNAi) emerging as a precise and sustainable strategy for managing plant viral diseases. RNAi operates through endogenous gene regulatory mechanisms and is driven by small RNAs (sRNAs) such as small interfering RNAs (siRNAs) and microRNAs (miRNAs). Through mechanisms such as post-transcriptional gene silencing (PTGS) and transcriptional gene silencing (TGS), sRNAs orchestrate a robust and multilayered immune response against plant viruses. Recent advances have expanded RNAi-based strategies to both transgenic and non-transgenic platforms. Transgenic approaches such as host-induced gene silencing (HIGS), provide stable and long-term resistance, while non-transgenic methods like spray-induced gene silencing (SIGS) and other exogenous nucleic acid delivery systems offer flexible and environmentally safe alternatives without genetic modification. Furthermore, engineered sRNAs such as artificial microRNA (amiRNA) and synthetic trans-acting small interfering RNA (syn-tasiRNA) enhance target specificity, enable multiplex targeting and reduce off-target effects. This review aims to bridge the fundamental concepts of sRNA biology with their application in antiviral crop protection. It provides a comprehensive overview of sRNA biogenesis, antiviral mechanisms and engineered sRNA technologies for plant virus management.