Abstract
In this study, we addressed the sex- and tissue-specific expression patterns of odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) in Hylamorpha elegans (Burmeister), an important native scarab beetle pest species from Chile. Similar to other members of its family, this scarab beetle exhibit habits that make difficult to control the pest by conventional methods. Hence, alternative ways to manage the pest populations based on chemical communication and signaling (such as disrupting mating or host finding process) are highly desirable. However, developing pest-control methods based on chemical communication requires to understand the molecular basis for pheromone recognition/chemical perception in this species. Thus, with the aim of discovering olfaction-related genes, we obtained the first reference transcriptome assembly of H. elegans. We used different tissues of adult beetles from males and females: antennae and maxillary palps, which are well known for embedded sensory organs. Then, the expression of predicted odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) was analyzed by qRT-PCR. In total, 165 transcripts related to chemoperception were predicted. Of these, 16 OBPs, including one pheromone-binding protein (PBP), and four CSPs were successfully amplified by qRT-PCR. All of these genes were differentially expressed in the sensory tissues with respect to the tibial tissue that was used as a control. The single predicted PBP found was highly expressed in the antennal tissues, particularly in males, while several OBPs and one CSP showed male-biased expression patterns, suggesting that these proteins may participate in sexual recognition process. In addition, a single CSP was expressed at higher levels in female palps than in any other studied condition, suggesting that this CSP would participate in oviposition process. Finally, all four CSPs exhibited palp-biased expression while mixed results were obtained for the expression of the OBPs, which were more abundant in the palps than in the antennae. These results suggest that these chemoperception proteins would be interesting novel targets for control of H. elegans, thus providing a theoretical basis for further studies involving new pest control methods.
Highlights
Chemical perception in insects relies on olfaction and gustation, which enable insects to accomplish important tasks such as mating, host finding and predator avoidance in their environment (Sánchez-Gracia, Vieira & Rozas, 2009)
A recent report revealed an olfactory protein linked to the ability to perceive volatiles commonly used in chemical communication by Scarabaeidae species (Venthur et al, 2014; González-González et al, 2016), which suggests that a similar mechanism could be involved in chemical communication in H. elegans. Considering this information, our goals were to identify the repertoire of proteins related to taste and olfaction in adults of Hylamorpha elegans by performing a transcriptome analysis and comparing the relative expressions of odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) in different tissues of both sexes; we hypothesized that OBPs and CSPs are highly expressed in the antennae and palps compared to their expression in a nonsensory tissue, and there are differential expression patterns of these transcripts between males and females
An additional BUSCO analysis against Arthropoda and Endopterygota is shown in Table 4, with similar completeness values
Summary
Chemical perception in insects relies on olfaction and gustation, which enable insects to accomplish important tasks such as mating, host finding and predator avoidance in their environment (Sánchez-Gracia, Vieira & Rozas, 2009). The most important insect carrier proteins are chemosensory proteins (CSPs) and odorant-binding proteins (OBPs), both of which are responsible for recognizing (Leal, 2013; Li et al, 2013) and transporting volatiles, typically hydrophobic molecules (Gadenne, Barrozo & Anton, 2016), from the sensillar pores to the membrane receptors located in the dendrites of the neuron (Pelosi et al, 2018). These proteins are the first step in the cascade of events that compromise the olfactory and gustatory processes (Leal, 2013)
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