Knockdown of Mythimna separata Chitinase Genes via Oral delivery of RNAi effectors

RNAi (RNA interference) technology has been used to develop insect and disease resistant crops. Mythimna separata belongs to noctuidae family of lepidoptera and is posing threat to crops of economic importance. Recently, outbreaks of M. separata severely threaten corn production in Northern China, calling for new control approaches. The team of Oyunchuluun Ganbaatar from Inner Mongolia University chose to target chitinase genes as they were expressed predominantly in the gut tissue and were reported to be ideal silencing targets in several insect species.

Interfering sequences against the target genes were cloned into the L4440 vector to produce sequence specific dsRNAs (double-stranded RNAs). These were then transformed into Escherichia coli strain HT115 (DE3). The bacteria were mixed with artificial diet and were fed to M. separata.

Analysis showed that expression level of target MseChi1 and MseChi2 genes in gut tissue of M. separata were downregulated after oral delivery of engineered bacteria expressing the corresponding dsRNA. Furthermore, knockdown of MseChi1 and MseChi2 resulted in increased mortality and reduced body weight of the feeding larvae.

This study reports a simple and low cost experimental procedure to silence M. separata endogenous gene expression. This provides both an experimental foundation for using RNAi technology to control M. separata and also a tool for loss-of-function studies of genes in this species.

For more on this study, read the article in BMC Biotechnology.