P-086 - RNAi as a tool for the control of Cucurbit Yellowing viruses

Cucurbit Yellowing viruses: cucurbit yellow stunting disorder virus (CYSDV) and cucurbit chlorotic yellows virus (CCYV) are among the most common and significant pathogens affecting cucurbits crops in the U.S Southwest. RNA interference (RNAi) serves as an important anti-viral mechanism in eukaryotes and has been explored as a non-transgenic strategy for plant diseases control. This approach involves the application of exogenous dsRNA, which triggers the suppression of pathogen gene activity in a homology-dependent manner. In this study, we synthesized ~ 500 nucleotides (nt) dsRNA homologous to the CYSDV CP gene using the MEGAscript™ T7 Transcription Kit and Escherichia coli (HT115)/L4440 in vivo system. CYSDV CP-dsRNA (~80ng/µL) was sprayed on melon plants 48 hours before the virus transmission by viruliferous whiteflies (n = 50/ per leaf). qPCR analysis revealed a silencing effect on CP gene on CP-dsRNA-treated plants ten days post-inoculation. CYSDV symptoms alleviation was also observed. Furthermore, the dsRNA-CP was detected in non-treated distant leaves by digital PCR up to120 hours after spray, suggesting a systemic moving effect. Altogether our findings highlight the potential of RNAi technology for controlling CYSDV in melon plants.