AUTHOR=Rong Haoling , He Xin , Liu Yipeng , Liu Mei , Liu Xiaolong , Lu Min 

TITLE=Odorant binding protein 18 increases the pathogen resistance of the imported willow leaf beetle, Plagiodera versicolora

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2024.1360680

DOI=10.3389/fcimb.2024.1360680

ISSN=2235-2988

ABSTRACT=<sec><title>Background</title><p>Insect odorant-binding proteins (OBPs) are a class of small molecular weight soluble proteins. In the past few years, OBPs had been found to work as carriers of ligands and play a crucial role in olfaction and various other physiological processes, like immunity. A subset of insect OBPs had been found to be expressed differently and play a function in immunity of fungal infection. However, there are few studies on the role of OBPs in immunity of bacterial infection.</p></sec><sec><title>Methods</title><p>To identify the immune-related OBPs of <italic>Plagiodera versicolora</italic> after infected by <italic>Pseudomonas aeruginosa</italic>, we determined the mortality of <italic>P. versicolora</italic> to <italic>P. aeruginosa</italic> and selected the time point of 50% mortality of larvae to collect samples for RNA-seq. RNAi technology was used to investigate the function of immune-related OBPs after <italic>P. aeruginosa</italic> infection.</p></sec><sec><title>Results</title><p>RNA-seq data shows that <italic>PverOBP18</italic> gene significantly up-regulated by 1.8-fold and further RT-qPCR affirmed its expression. Developmental expression profile showed that the expression of <italic>PverOBP18</italic> was highest in the pupae, followed by the female adults, and lower in the 1st-3rd larvae and male adults with lowest in eggs. Tissue expression profiling showed that <italic>PverOBP18</italic> was dominantly expressed in the epidermis. RNAi knockdown of <italic>PverOBP18</italic> significantly reduced the expression of bacterial recognition receptor gene <italic>PGRP</italic> and antibacterial peptide gene <italic>Attacin</italic> and reduced the resistance of <italic>P. versicolora</italic> to <italic>P. aeruginosa</italic> infection.</p></sec><sec><title>Conclusion</title><p>Our results indicated that <italic>PverOBP18</italic> gene increased the pathogen resistance of <italic>P. versicolora</italic> by cooperating with the immune genes and provided valuable insights into using OBPs as targets to design novel strategies for management of <italic>P. versicolora.</italic></p></sec>