Chemosensory Gene Families in Adult Antennae of Anomala corpulenta Motschulsky (Coleoptera: Scarabaeidae: Rutelinae)

Abstract

BackgroundThe metallic green beetle, Anomala corpulenta (Coleoptera: Scarabaeidae: Rutelinae), is a destructive pest in agriculture and horticulture throughout Asia, including China. Olfaction plays a crucial role in the survival and reproduction of A. corpulenta. As a non-model species, A. corpulenta is poorly understood, and information regarding the molecular mechanisms underlying olfaction in A. corpulenta and other scarab species is scant.Methodology/Principle FindingsWe assembled separate antennal transcriptome for male and female A. corpulenta using Illumina sequencing technology. The relative abundance of transcripts with gene ontology annotations, including those related to olfaction in males and females was highly similar. Transcripts encoding 15 putative odorant binding proteins, five chemosensory proteins, one sensory neuron membrane protein, 43 odorant receptors, eight gustatory receptors, and five ionotropic receptors were identified. The sequences of all of these chemosensory-related transcripts were confirmed using reverse transcription polymerase chain reaction (RT-PCR), and direct DNA sequencing. The expression patterns of 54 putative chemosensory genes were analyzed using quantitative real time RT-PCR (qRT-PCR). Antenna-specific expression was detected for many of these genes, suggesting that they may have important functions in semiochemical detection.ConclusionsThe identification of a large number of chemosensory proteins provides a major resource for the study of the molecular mechanism of odorant detection in A. corpulenta and its chemical ecology. The genes identified, especially those that were expressed at high levels in the antennae may represent novel molecular targets for the development of population control strategies based on the manipulation of chemoreception-driven behaviors.

Odorant receptors and antennal lobe morphology offer a new approach to understanding olfaction in the Asian longhorned beetle

“…This cluster may thus be under active selection in A. glabripennis , although no members were prominent in the transcriptomes. Group 2 is recovered with strong statistical support in other studies (Engsontia et al 2008; Andersson et al 2013; Li et al 2015; RFM unpub. data), so its poor support in the present study is questionable, but it may reflect a division that will become evident as additional beetle genomes are sequenced.…”

“…data). Some authors have even gone so far as to entirely remove them from analyses (Andersson et al 2013; Li et al 2015). It is possible TcasOR71-72 are remnants of a separate, diminished group of receptors in Tribolium that are lost in Anoplophora and the other beetle families included in our analyses.…”

“…ORs of A. glabripennis were separately aligned with the three functionally characterized ORs from M. caryae , the OR genes available from the genome of T. castaneum , and published ORs from transcriptomes of three other major beetle families: Chrysomelidae ( Ambrostoma quadriimpressum Motchulsky; Wang et al 2016), Scarabaeidae ( Anomala corpulenta Motchulsky; Li et al 2015), and Curculionidae ( D. ponderosae ). Only genes longer than 100 amino acids were included in this analysis.…”

“…), six of which were annotated from the genome of T. castaneum (Engsontia et al 2008). The final subfamily in the scheme, Group 7, was subsequently identified from several other beetle families (Mitchell et al 2012; Andersson et al 2013; Li et al 2015) but apparently is absent in T. castaneum .…”

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“…Insects of different orders usually have a large number of antennal-expressed ORs. For example, in Lepidoptera: Helicoverpa assulta (64 ORs) (Zhang et al, 2015b), Helicoverpa arminera (60 ORs) (Zhang et al, 2015b), and Bombyx mori (66 ORs) (Wanner & Robertson, 2008;Tanaka et al, 2009); in Coleoptera: Rhynchophorus ferrunineus (77 ORs) (Antony et al, 2016) and Anomala corpulenta (43 ORs) (Li et al, 2015a); in Hymenoptera: Chouioia cunea (80 ORs) (Zhao et al, 2016) and Atta vollenweiteri (70 ORs) (Koch et al, 2013); in Diptera: Bactrocera torsalis (43 ORs) (Jin et al, 2017); and in Neuroptera: Chrysoperla sinica (37 ORs) (Li et al, 2015b). As a receptor that is strikingly different from all other insect olfactory receptors, Orco is highly conserved in insect species and widely expressed.…”