RNA-seq Analysis Reveals the Response of Tribolium castaneum to the T4ol Exposure

Terpinen-4-ol, one of the terpenes, is known to be contact toxicity that disturbed the Tribolium castaneum. However, the molecular mechanisms underlying the toxic effects of T4ol on T. castaneum remains unclear. In this study, four classic enzymes were detected after T4ol exposure. Among of which, a nerve conduction enzyme acetyl choline esterase (AChE) were dramatically inhibited, while a detoxifying enzyme cytochrome oxidase P450 (CYP) were dramatically increased. Further, 260 genes were differentially expressed between T4ol treated and control samples by RNA-sequencing. The RNA-sequencing data were further validated by qRT-PCR. Based on Gene Ontology (GO) analysis, these DEGs were classified into 36 GO functional groups, including such functions as the immune system process, the response to stimulus, and the developmental process. These DEGs showed that T4ol disturbed the response to stimulus and immune system process of beetles by inducing the expression of genes encoding Stabilin 1, Attacin 1, and Defensin 1. Additionally, the DEGs encoding Receptor tyrosine kinase Torso-like protein (RTKTsl), Frizzled 4 (Fz4), Protein Wnt-5b, Ecdysone-induced protein 78C (E78), Zinc finger protein GLIS1 (ZFPGLIS1) would participate in the development of beetles, of which Fz4 and Protein Wnt-5b were also mapped into Wnt signaling pathway, indicating that the pathway associated with development are inhibited following T4ol exposure. Interestingly, T4ol induced overexpression of CYP9Z6/GSTs7 and RNAi against these genes significantly increased mortality of larvae exposed to T4ol, providing evidence for the involvement of CYP9Z6/GSTs7 in response to T4ol in T. castaneum. This study will be of service to the toxic mechanisms of T4ol and provides the basics for controlling stored product pests.