Immune-related genes of the larval Holotrichia parallela in response to entomopathogenic nematodes Heterorhabditis beicherriana LF

Abstract

Background Entomopathogenic nematodes (EPNs) emerge as compatible alternatives to conventional insecticides in controlling Holotrichia parallela larvae (Coleoptera: Scarabaeidae). However, the immune responses of H. parallela against EPNs infection remain unclear. Results In present research, RNA-Seq was firstly performed. A total of 89427 and 85741 unigenes were achieved from the midgut of H. parallela larvae treated with Heterorhabditis beicherriana LF for 24 and 72 h, respectively; 2545 and 3156 unigenes were differentially regulated, respectively. Among those differentially expressed genes (DEGs), 74 were identified potentially related to the immune response. Notably, some immune-related genes, such as peptidoglycan recognition protein SC1 (PGRP-SC1), pro-phenoloxidase activating enzyme-I (PPAE-I) and glutathione s-transferase (GST), were induced at both treatment points. Bioinformatics analysis showed that PGRP-SC1, PPAE-I and GST were all involved in anti-parasitic immune process. Quantitative real-time PCR (qRT-PCR) results showed that the three immune-related genes were expressed in all developmental stages; PGRP-SC1 and PPAE-I had higher expressions in midgut and fat body, respectively, while GST exhibited high expression in both of them. Moreover, in vivo silencing of them resulted in increased susceptibility of H. parallela larvae to H. beicherriana LF. Conclusion These results suggest that PGRP-SC1, PPAE-I and GST could be used as target genes to disturb the immune system of H. parallela. This study provides the first comprehensive transcriptome resource of H. parallela exposure to nematode challenge that will help to support further comparative studies on host-EPN interactions.

Insect Defense System and Immunosuppression Strategies of Entomopathogenic Nematodes - An Overview

“…Physiological defenses in chrysomelid beetles and mosquitoes frequently result in encapsulation and melanization of infective juveniles after penetrating the hemocoel . Haemocytes in presence of foreign targets are activated by the presence of PAMPs and /or endogenous soluble factors and initiate complex mechanisms such as intracellular signal transduction which activate the specific immune genes and initiates defense mechanisms such as phagocytosis, nodulation ,encapsulation , synthesis of antimicrobial peptides and cell-mediated melanization ( Chapman,1998;Schmidt et al, 2001;Williams ,2007;Strand 2008;Krzemien et al,2011;Li et al,2021).…”