Functional Characterization of a Trehalose-6-Phosphate Synthase in Diaphorina citri Revealed by RNA Interference and Transcriptome Sequencing

SIMPLE SUMMARY: Trehalose-6-phosphate synthase (TPS) is a key enzyme in regulating trehalose content in the insect hemolymph. The loss or dysfunction significantly affects the growth and development of insects. Diaphorina citri is a notorious phloem sap-sucking pest that can spread huanglongbing between the diseased tree and the healthy tree. The control of huanglongbing mainly depends the management of D. citri. So far, the management of D. citri populations has depended on using chemical pesticides, though pesticide abuse has caused serious problems. Therefore, it necessary to find new targets for D. citri control. In this paper, we identified a TPS gene from Diaphorina citri, and named it DcTPS1. Silencing of DcTPS1 induced an abnormal phenotype, and inhibited chitin metabolism and fatty acid metabolism. Moreover, the mortality and malformation rate significantly increased, and the molting rate decreased after inhibition of DcTPS1. KEGG analysis revealed that upregulated DEGs were mainly responsible for oxidative phosphorylation, whereas downregulated DEGs were mainly related to lysosome and ribosome. Overall, our data suggested that DcTPS1 might play a crucial role for the growth and development of D. citri. ABSTRACT: Trehalose-6-phosphate synthase (TPS) plays an important role in the synthesis of trehalose. In the current study, a TPS gene was obtained from Diaphorina citri, and named as DcTPS1 which encoded a protein of 833 amino acid residues. Real-time quantitative PCR (qPCR) analysis revealed that DcTPS1 had the highest expression level in the midgut and fifth-instar nymph stage. Knockdown of DcTPS1 by RNA interference (RNAi) induced an abnormal phenotype and increased mortality and malformation rate with a decreased molting rate. In addition, silencing of DcTPS1 significantly inhibited D. citri chitin metabolism and fatty acid metabolism, while the expression levels of fatty acid decomposition-related genes were downregulated. Furthermore, comparative transcriptomics analysis revealed that 791 differentially expressed genes (DEGs) were upregulated and 678 DEGs were downregulated when comparing dsDcTPS1 groups with dsGFP groups. Bioinformatics analysis showed that upregulated DEGs were mainly involved in oxidative phosphorylation, whereas downregulated DEGs were mainly attributed to the lysosome and ribosome. These results indicated that DcTPS1 played an important role in the growth and development of D. citri.