Abstract: Acetylcholinestrase (AChE) is one of the key enzymes in cholinergic nervous system. One of the neurotransmitters, named acetylcholine, can be hydrolyzed rapidly by AChE. In this study, an acetylcholinesterase gene MsAChE (GenBank accession number: PP473664) of Mythimna separata was successfully identified and cloned. The length sequence of MsAChE was 5430 bp with an open reading frame (ORF) of 1917 bp, encoding 638 amino acids. The qRT-PCR results showed that MsAChE was expressed in all tested developmental stages and tissues. In order to explore its biological function, the MsAChE was silenced by RNAi to study the effect on the growth and development of M. separata. The interference efficiency experiment demonstrated successful silencing of MsAChE, resulting in significant inhibition of gene expression within 3 to 24 hours. When RNA interfered for 6 h, the gene silencing effect was the most significant, and the gene expression decreased by 78.84%. Enzyme activity itially increased before decreasing, and the mortality of RNA-interfered M.separata treated with chlorpyrifos and carbaryl also increased significantly, reaching 71.1% and 58.9% respectively at 24 h after treatment. Transcriptome data revealed alterations in the expression levels of numerous key differential genes associated with signal transduction and metabolism in M. separata. These findings suggest that the MsAChE gene plays a crucial role in essential pathways, including metabolism and signal transduction. It provides a foundation for further investigations of the biological function of AChE, and laid a theoretical basis for development of the AchE-targeted insecticides.

Key words: Mythimna separata, acetylcholinestrase, RNA interference, transcriptome analysis