Identification and preliminary characterization of chemosensory-related proteins in the gall fly, Procecidochares utilis by transcriptomic analysis

Abstract

Background: Chemoreception is critical for insect behaviors such as foraging, host searching and oviposition, and finding mating partners. The process of chemoreception is mediated by a series of proteins, including odorant-binding proteins (OBPs), gustatory receptors (GRs), odorant receptors (ORs), ionotropic receptors (IRs), chemosensory proteins (CSPs) and sensory neuron membrane proteins (SNMPs). The tephritid stem gall fly, Procecidochares utilis Stone, is a type of egg parasitic insect, which is an effective biological control reagent for the invasive weed Ageratina adenophora in many countries. However, the study of molecular components related to the olfactory system of P. utilis has not been investigated. Here, we report the developmental transcriptome (egg, first-third instar larvae, pupae, fame and male adult) of P. utilis using next-generation sequencing technology and identified the major chemosensory related genes. Results: In this study, a total of 133 chemosensory genes in P. utilis transcriptomes were identified by bioinformatics analysis, including 40 OBPs, 29 GRs, 24 ORs, 28 IRs, 6 CSPs, and 6 SNMPs in P. utilis. The sequences of these candidate chemosensory genes were confirmed by BLAST, and phylogenetic analysis was performed. The expression profiles of all candidate genes at different developmental stages were analyzed by differentially expressed genes (DEGs) analysis and then the expression profiles of the OBPs in the seven developmental stages were confirmed by real-time quantitative RT-PCR (qPCR). The results showed that the expression of candidate OBP genes across different developmental stages was consistent with the differentially expressed genes (DEGs) analysis using the fragments per kilobase per million fragments (FPKM) value. Conclusions: A large number of chemosensory genes were identified. This study will provide a significant contribution to the molecular mechanism of chemoreception and help advance the use of P. utilis as biological control agents. Introduction: The chemosensory system is essential for the survival and reproduction of insects. Insects rely on the chemosensory system to identify and analyze volatiles, as well as to distinguish unique chemical signals in their living environment, which play vital roles in their ecological adaptations, host plant location, mate selection, reproductive behavior and other important physiological processes [1, 2]. The system is mediated by several important chemosensory proteins, including odorant-binding proteins (OBPs), chemosensory proteins (CSPs), olfactory receptors (ORs), ionotropic receptors (IRs), and sensory neuron membrane proteins (SNMPs) [2]. OBPs are small, globular, and water-soluble proteins that are recognized as playing an important role in the first step of olfactory recognition [3-5]. Insect OBPs bind and transport hydrophobic odorant molecules through the aqueous lymph within its sensilla to the olfactory receptors (ORs) and activate ORs in the dendritic membranes of the olfactory neurons [6, 7]. Generally, insect...

Transcriptome analysis and identification of chemosensory genes in the larvae of Plagiodera versicolora

“…Two special PverOBPs ( OBP33 and 37 ) were highly expressed in pupae which were also consistent with the results obtained in other species. For example, five OBPs in Procecidochares utilis , OBP44a in Bactrocera dorsalis , and three OBPs ( OBP15 , 17 , and 25 ) in Galeruca daurica were found to be abundantly expressed in the pupal stage, respectively [ 79 – 81 ]. In addition, PverOR42 was highly expressed in pupae, the same as three ORs in P. utilis and eight ORs in Chlorops oryzae [ 79 , 82 ].…”

“…For example, five OBPs in Procecidochares utilis , OBP44a in Bactrocera dorsalis , and three OBPs ( OBP15 , 17 , and 25 ) in Galeruca daurica were found to be abundantly expressed in the pupal stage, respectively [ 79 – 81 ]. In addition, PverOR42 was highly expressed in pupae, the same as three ORs in P. utilis and eight ORs in Chlorops oryzae [ 79 , 82 ]. These results suggest that these OBPs and ORs in P. versicolora may be related to the beginning of the development of chemosensory tissue during pupation.…”

Comparative Transcriptomic Analysis of Riptortus pedestris (Hemiptera: Alydidae) to Characterize Wing Formation across All Developmental Stages

“…The domain distribution of all translated amino acid sequences was determined using the SMART server ( , accessed on 10 November 2020), TMHMM 2.0 ( , accessed on 10 November 2020) and SignalP 4.0 ( , accessed on 10 November 2020). Finally, the molecular weight and theoretical isoelectric point of all the proteins were estimated with the Expasy ProtParam tool ( , accessed on 10 November 2020) [ 26 , 27 ].…”

Role of Genes in Regulating Host Plants Expansion in Tephritid Fruit Flies (Diptera) and Potential for RNAi-Based Control

“…Volatile chemicals stimulate chemosensory (olfactory and gustatory) receptors in tephritid flies when assessing a potential novel host and trying to expand (Li et al 2020). Therefore, chemosensory-related genes are involved in the initial process of host plant expansion for tephritids.…”

“…OBP genes play an important role in the first step of chemosensory identification of insects, including tephritids (Song et al 2018 (Campanini et al 2017) to related olfactory receptors that are bound to olfactory receptor neurons (ORNs) in antennae (Ono et al 2021). CSP genes are regarded as playing a similar role as OBP genes involved in the initial process of chemosensory signal transmission to corresponding receptors (Li et al 2020). OBP and CSP genes are major gene types that lead tephritid flies to respond to different chemosensory chemicals, including volatile chemicals of host plants (Xu et al 2019).…”