Functional olfactomics in Lepidoptera: identification and characterization of olfactory receptors in the cotton leafworm Spodoptera littoralis.

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عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
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چکیده
Today, entomology is facing the new era of high-throughput sequencing, with cumulative transcriptomics and genomics data available on a diversity of model and non-model species. Challenges are to exploit this diversity and to develop functional tools, especially in non-model species. Using the crop pest moth Spodoptera littoralis (Lepidoptera; Noctuidae) as a model species in chemical ecology, we developed such tools for the study of olfactory receptors (ORs). These ORs are transmembrane proteins expressed in olfactory sensory neurons, and they are at the core of odorant detection. Each species has evolved a unique repertoire of ORs whose functional properties are expected to meet its ecological needs, though little is known about the molecular basis of olfaction outside Diptera.
Using transcriptomics and genomics, we identified the complete set of olfactory receptors in S. littoralis. Heterologous expression in Drosophila antennae coupled to electrophysiology was used to functionally characterize these receptors. As a complementary tool, we established genome editing in this species via CRISPR/Cas9 to knock-out olfactory receptors.
We report a pioneer functional analysis of a large array of ORs in a Lepidoptera. We demonstrated that most ORs are narrowly tuned to ubiquitous plant volatiles at low, relevant odorant titres. A phylogenetic analysis highlighted a basic conservation of function within the receptor repertoire of Lepidoptera, across the expansive evolutionary radiation of different major clades. We also demonstrate that the CRISPR/Cas9 system is highly efficient for genome editing in this crop pest: knocking-out the olfactory receptor co-receptor Orco gene caused defects in plant odor and sex pheromone olfactory detection in homozygous individuals. Our work opens new routes for gene function analysis and in fine the development of novel pest control strategies.
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