AUTHOR=Dong Jun-Feng , Yang Hai-Bo , Li Ding-Xu , Yu Hong-Qi , Tian Cai-Hong 

TITLE=Identification and expression analysis of chemosensory receptors in the tarsi of fall armyworm, Spodoptera frugiperda (J. E. Smith)

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1177297

DOI=10.3389/fphys.2023.1177297

ISSN=1664-042X

ABSTRACT=<p>Chemosensation of tarsi provides moths with the ability to detect chemical signals which are important for food recognition. However, molecular mechanisms underlying the chemosensory roles of tarsi are still unknown. The fall armyworm <italic>Spodoptera frugiperda</italic> is a serious moth pest that can damage many plants worldwide. In the current study, we conducted transcriptome sequencing with total RNA extracted from <italic>S. frugiperda</italic> tarsi. Through sequence assembly and gene annotation, 23 odorant receptors 10 gustatory receptors and 10 inotropic receptors (IRs) were identified. Further phylogenetic analysis with these genes and homologs from other insect species indicated specific genes, including ORco, carbon dioxide receptors, fructose receptor, IR co-receptors, and sugar receptors were expressed in the tarsi of <italic>S. frugiperda</italic>. Expression profiling with RT-qPCR in different tissues of adult <italic>S</italic>. <italic>frugiperda</italic> showed that most annotated <italic>SfruORs</italic> and <italic>SfruIRs</italic> were mainly expressed in the antennae, and most <italic>SfruGR</italic>s were mainly expressed in the proboscises. However, <italic>SfruOR30</italic>, <italic>SfruGR9</italic>, <italic>SfruIR60a</italic>, <italic>SfruIR64a</italic>, <italic>SfruIR75d</italic>, and <italic>SfruIR76b</italic> were also highly enriched in the tarsi of <italic>S</italic>. <italic>frugiperda</italic>. Especially <italic>SfruGR9</italic>, the putative fructose receptor, was predominantly expressed in the tarsi, and with its levels significantly higher in the female tarsi than in the male ones. Moreover, <italic>SfruIR60a</italic> was also found to be expressed with higher levels in the tarsi than in other tissues. This study not only improves our insight into the tarsal chemoreception systems of <italic>S</italic>. <italic>frugiperda</italic> but also provides useful information for further functional studies of chemosensory receptors in <italic>S. frugiperda</italic> tarsi.</p>