Identification and Tissue Expression Profiles of Odorant Receptor Genes in the Green Peach Aphid Myzus persicae

SIMPLE SUMMARY: The green peach aphid is a pest that mainly endangers vegetables. It spreads a variety of plant viruses through pricking and sucking plant juice. At the same time, it also secretes honeydew, which causes mildew and pollution and leads to the loss of many crops. Olfaction plays a very important role in the aphids’ search for hosts, avoidance of natural enemies, mating and oviposition. However, the molecular mechanism of olfactory recognition in the green peach aphid is not clear. Odorant receptors (ORs) are a type of olfactory neuron membrane receptor expressed on insect antennae and they play a role in identifying odorants from the environment. We identified 33 OR genes from the genome and transcriptomes of the green peach aphid and analyzed their phylogenetic relationship and genomic structure. We further examined the expression patterns in different tissues by real-time quantitative PCR (RT-qPCR). This study enriches our understanding of the olfactory system of the green peach aphid and will help to better apply it to the integrated control of a variety of pests. ABSTRACT: The green peach aphid Myzus persicae (Hemiptera: Aphididae) relies heavily on its olfactory system to locate plant hosts, find mates, and avoid parasitoids or predators. The insect odorant receptors (ORs) have been proven to play a critical role in the perception of odorants from the environment. In the present study, 33 odorant receptor candidate genes including the Orco gene were identified from the antennal, head, legs and body transcriptomes of M. persicae. Phylogenetic analysis of ORs from seven different orders of insect species suggests that ORs from different insect species are highly divergent and most ORs from the same species formed monophyletic groups. In addition, the aphid ORs were clustered into six different sub-clades in the same clade. Furthermore, the genomic structure of the OR genes also tends to be consistent, suggesting that ORs from the family Aphididae have a relatively close evolutionary relationship. Reads per kilobase per million (RPKM) and tissue expression profiles analyses revealed that 27 out of the 33 MperORs were uniquely or primarily expressed in the antennae, indicating their putative roles in chemoreception. This work provides a foundation to further investigate the molecular and ecological functions of MperORs in the aphid–aphid, aphid–plant and aphid–natural enemy interactions.