Expression And Function Analysis Of Gustatory Receptor In Coptotermes Formosanus Shiraki

Coptotermes formosanus Shiraki,a subterranean termite species,is widespread across China and causes serious damage to buildings and forestry crops.As a social insect,C.formosanus relies heavily on its chemosensory system for various tasks,such as foraging,nest maintenace,defensing,and tracing of nestmates.This study investigates the function of gustatory receptor(GR)genes,especially the GRs that contribute to recognition of sugar and bitter compounds,providing insights into the biological mechanism of gustatory system in C.formosanus,and paving the way for eco-friendly termite control strategies.With the help of our C.formosanus transcriptome database,the expression level of gustatory receptor genes in different tissues was determined.The binding affinity of gustatory receptors to ligand substances(sugar and bitter componds)was estimated by molecular docking method.We further interfered these gustatory receptor genes by RNAi technology to understand their impact on the feeding behavior of C.formosanus workers.mainour main findings are have showed follows:By analyzing the C.formosanus transcriptome database and the related gene homology,protein structure analysis,and gene amplification process,we identified six open reading frames of gustatory receptor genes.Sequence clustering and phylogenetic analysis suggested that Cfor GR12 may be involved in sugar recognition,while Cfor GR23 may have a role in bitter compound detection.Tissue expression profiles revealed that each receptor gene was expressed in various termite body parts.For detail,Cfor GR2 was highly expressed in antennae,mouthpart,head and legs of workers;Cfor GR10 was highly expressed in antennae,mouthpart and legs;and Cfor GR12 was only highly expressed in head;Cfor GR13 had higher expression in antennae and legs;Cfor GR14 was highly expressed in antennae,mouthpart and legs;Cfor GR23 was highly expressed in antennae,head,mouthpart and body,which was consistent with the expression patterns of gustatory receptor genes.Molecular docking wree employed to predict the binding affinity of gustatory receptors to various of ligands.Our result showed that the binding affinity of Cfor GR10 with trehalose,cellobiose and lactose were-7.1 kcal/mol,-7.3 kcal/mol and-7.3 kcal/mol,respectively;The binding affinity of Cfor GR12 with trehalose and cellobiose were-7.4 kcal/mol and-7.3 kcal/mol,respectively.The binding affinity between Cfor GR14 and cellobiose was-7.1 kcal/mol.Binding affinity of Cfor GR23 and quinine was the highest,which was-8.0 kcal/mol.Consequently,Cfor GR10,Cfor GR12,and Cfor GR14 may recognize trehalose,cellobiose,and lactose,while Cfor GR23 showed the strongest binding to quinine,a bitter compound.Behavioral and RNAi assays revealed that fructose recognition my modulated by Cfor GR14,although it binding affinity with fructose was not strong.Furthermore,C.formosanus displayed an repellency response to quinine,which was weakened upon Cfor GR23 gene interference,suggesting that Cfor GR23 might contribute to quinine recognition.In summary,this study reveals the potential involvement of gustatory receptor genes in sugar and bitter compound recognition in C.formosanus,offering new insights into the termite’s chemosensory system and novel targets for environmentally friendly pest management.