Topical application of double stranded RNA molecules deriving from Sesbania mosaic virus (SeMV) CP and MP genes protects Sesbania plants against SeMV

RNA interference (RNAi) is a sequence-specific, gene silencing mechanism, induced by double-stranded RNA (dsRNA). It is a defense mechanism that protects eukaryotic cells from invasive nucleic acids such as viruses and transposons. In this study, we used a non-transgenic strategy in order to activate the antiviral RNAi mechanism against Sesbania mosaic virus (SeMV) in its natural host Sesbania grandiflora. DsRNA molecules from SeMV coat protein (CP) and movement protein (MP) (sobemovirus MP is considered a silencing suppressor) genes were produced by a two-step PCR approach followed by in vitro transcription and exogenously applied on sesbania plants along with SeMV. DsRNA for CP and MP conferred 53% and 64% resistance against SeMV, respectively based on the disease incidence data. The effect of dsRNA molecules against SeMV infection on sesbania plants was confirmed by direct antigen coating ELISA (DAC-ELISA). The strategy employed demonstrated the applicability of the RNA-based vaccination method, for the first time, to control sobemoviruses in a simple, highly specific and environmentally safe way.