Protective roles of chitin synthase gene 1 in Nilaparvata lugens against Cordyceps javanica and insecticides

Abstract

The chitin synthase gene 1 (CHS1) is a key gene in insect chitin synthesis pathway, it plays a critical role in the insect's survival and development. However, the protective functions of CHS1 in response to pathogens and chemical insecticides remain poorly understood. In this study, we analyzed the functional domain and phylogenetic relationship of CHS1 in Nilaparvata lugens and other insects. Our findings revealed a conserved C-terminal domain in the CHS1 protein, as well as an evolutionary conservation across insect species. And then we found the CHS1 gene was highly expressed during the fifth instar nymph stage, and there was a differential expression and regulation of CHS1 in response to pathogen infection and exposure to various chemical insecticides. After that, we further discovered RNA interference (RNAi) mediated knockdown of CHS1 significantly increased the susceptibility of N. lugens to Cordyceps javanica and two chemical insecticides, nitenpyram and dinotefuran, but had no effect on triflumezopyrim. And we used scanning electron microscope to observe an increase in appressoria formation on the cuticle of N. lugens following CHS1 knock down, which accelerated the infection by C. javanica. These findings showed that CHS1 in N. lugens provide protection against pathogen and chemical insecticides, and highlighted the potential of targeting CHS1 to develop novel pest management strategies.