Abstract
Simple SummaryRNA interference (RNAi) has shown great potentials as a novel technology for insect pest management. However, numerous studies have shown that the efficiency of RNAi varies substantially among different insect species. For example, as a major insect pest of corn, the Asian corn borer (Ostrinia furnacalis) showed very low RNAi efficiency. Therefore, it is necessary to develop new strategies for enhancing RNAi efficiency in insects with low RNAi efficiency. In this study, six core RNAi pathway genes were identified and characterized from O. furnacalis transcriptome database. After dsEGFP was injected into O. furnacalis, the expression of the core RNAi pathway genes (OfDicer2 and OfAgo2) was significantly up-regulated in response to the exposure of dsEGFP. As a result, the RNAi efficiency against the target genes in certain tissues of O. furnacalis was significantly improved. These results suggest that RNAi efficiency can be improved by inducing the expression of key RNAi pathway genes in O. furnacalis.RNA interference (RNAi) is a sequence-specific gene silencing mechanism that holds great promise for effective management of agricultural pests. Previous studies have shown that the efficacy of RNAi varies among different insect species, which limits its wide spread application in the field of crop protection. In this study, we identified and characterized six core RNAi pathway genes including OfDicer1, OfDicer2, OfR2D2, OfAgo1, OfAgo2, and OfAgo3 from the transcriptomic database of the Asian corn borer (Ostrinia furnacalis). Domain analysis showed that the six deduced proteins contained the necessary functional domains. Insect developmental stage- and tissue-specific expression analysis showed that five genes were expressed in all the stages and tissues examined except OfAgo3, which showed low expression in larvae, and high expression in pupae and adults and in the midgut. RT-qPCR was performed to examine the response of these six genes to exogenous double-stranded RNA (dsRNA). Interestingly, the transcript levels of OfDicer2 and OfAgo2 were significantly enhanced after the injection of dsEGFP at different time points and tissues investigated. Consequently, the RNAi efficiency in targeting the insect endogenous genes can be greatly enhanced in the hemolymph or midgut. Taken together, our investigations suggest that RNAi efficiency can be enhanced by pre-injection of dsRNA to induce the RNAi core machinery genes, which could be a useful strategy to improving RNAi efficiency for studying gene functions under laboratory conditions.
Highlights
RNA interference (RNAi) has become a powerful tool for gene functional studies and next-generation insect pest control [1,2], since its discovery by Andrew Z
The candidate core RNAi pathway genes were identified in the transcriptomic databases of O. furnacalis through local BLAST using the sequences of Bombyx mori Dicer1 (XP_028040138.1)
Since the expression of OfDicer2 and OfAgo2 was up-regulated for a long time after injection of dsEGFP, we evaluated the expression levels of OfDicer2 and OfAgo2 in three different tissues including hemolymph, integument, and midgut by reverse transcription quantitative PCR (RT-qPCR)
Summary
RNA interference (RNAi) has become a powerful tool for gene functional studies and next-generation insect pest control [1,2], since its discovery by Andrew Z. A myriad of reports have shown robust and systemic RNAi responses in various insect species belonging to Coleoptera [2,4] and Orthoptera [1,5,6]. In some insect species of Diptera, Lepidoptera, and Hemiptera, RNAi efficiency appeared very poor [7–11]. This variability in RNAi efficiency among various insect species greatly limits the widespread use of RNAi technology in both basic research and field applications for pest management
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