Enhancement of RNAi by using concatemerized double-stranded RNA

Abstract

BACKGROUND: RNA interference (RNAi) is a potential tool for functional characterization of genes and also in the management of insect pests. Accumulated literature reveals that the RNAi efficiency varies among insect species and is reported to be less efficient in lepidopteran insects. RESULTS: We attempted to enhance RNAi efficiency by concatemerizing short double-stranded RNA (dsRNA) sequence. Then the effectiveness of concatemerized dsRNAs (C-dsRNAs) was compared with non-concatemerized long dsRNA (NCL-dsRNA) in silencing of acetylcholinesterase (AChE) in the diamondback moth, Plutella xylostella (Lepidoptera), amajor pest on cruciferous vegetables. Results revealed that the C-dsRNAs enhanced the RNAi efficiency in terms of higher target gene silencing and consequently resulted in lower larval weight gain and highermortality compared to the NCL-dsRNA treatment. Even the lower concentration (0.5 𝛍g) of C-dsRNAs had a relatively similar effect to that of higher concentrations (2 𝛍g) of NCL-dsRNA. The enhanced RNAi efficiency with C-dsRNAs was plausibly due to the higher expression of core RNAi pathway genes, Dicer-2 and Argonaute-2 (Ago-2), which are known to govern the efficiency of RNAi. CONCLUSION:Overall, C-dsRNA enhanced the RNAi activity over routinely used long dsRNA in P. xylostella and this strategymay be applied for effectivemanagement of insect pests.