Molecular identification of a short-type peptidoglycan recongnition protein, GmPGRP-SC from Grapholitha molesta

Abstract

Peptidoglycan recognition protein (PGRP) as an important pattern recognition receptor, which is found in both invertebrates and vertebrates, play an important role in antibacterial immunity, due to its prominent ability in detecting and eliminating the infection pathogen. However, PGRPs mainly have been identified from Drosophila melanogaster and Bombyx mori, and there were few reports on other agricultural insects, epically about their functions and mechanism. In this study, a short – types PGRP gene named as GmPGRP-SC has been identified in the Grapholitha molesta, oriental fruit moth (OFM) based on analysis of the transcription group database of OFM from our laboratory and the National Center for Biotechnology Information (https://www.ncbi.nlm.nih.gov/). The GmPGRP-SC contains a highly conserved PGRP domain and has the closest genetic relationship with the PGRP gene of Leguminivora glycinivorella according to sequence and phylogenetic analyses. The real-time PCR method was used to analyze its expression pattern in the developmental stage of OFM and in different tissues of the larva of OFM. Finally, the relative expression levels of GmPGRP-SC gene in OFM were analyzed after infected by different treatment of Beauveria bassiana. The results showed that the total cDNA of GmPGRP-SC was 3 221 bp, and the coding regions was 2 268 bp, encoding 756 amino acid residues. The expression level of GmPGRP-SC was the highest in pupal stage of OFM, meanwhile in different tissues of OFM, its relative expression was higher in epithelium and hemocyte, while other stage and tissues were relatively low, and with little difference. The expression level of GmPGRP-SC was significance different when the spore suspension of B. bassiana was 105 conidia/μL infected after 48 h. And when the spore suspension of B. bassiana was 107 conidia/μL, the expression level of GmPGRP-SC was also significance different. All these results lay a foundation for the study of the role and functions of GmPGRP-SC in the innate immunity of OFM, and also do contribute to the further study of the molecular interaction between OFM and B. bassiana. The research results can help to find potential target molecules, and provide scientific basis for the development of new biogenic pesticides and the realization of Green Pest Management (GPM).