Identification and sex expression profiles of olfactory-related genes in Mythimna loreyi based on antennal transcriptome analysis

Abstract

• 138 olfactory-related genes were identified by transcriptome analysis in M. loreyi. • 22 olfactory-related genes showed sex-biased expression in adult antennae. • Some olfactory-related genes were highly biased in tissues other than antennae. To better understand the olfactory mechanism of Mythimna loreyi , a worldwide migratory pest, we for the first time conducted a large scale identification of olfactory-related genes and investigation of their sex expression profiles by transcriptomic analysis. A total of 42,832 unigenes were obtained by transcriptome sequencing, assembly and annotation, with an average length of 1,229 bp and N50 of 2,086 bp. In particular, 138 olfactory-related genes were identified by homologous blasting, including 33 odorant binding proteins (OBPs), 16 chemosensory proteins (CSPs), 63 odorant receptors (ORs), 24 ionotropic receptors (IRs) and two sensory neuron membrane proteins (SNMPs). Further, by using differential gene expression (DGE) and fragments per kilobase per million fragments (FPKM) values to compare the transcript levels between female and male antennae, we found that 22 olfactory-related genes (9 OBPs, one CSP and 12 ORs) were sex biased, with 10 genes being male biased and 12 genes female biased. In addition, sex and tissue expression profiles determined by qPCR of 15 selected genes confirmed the reliability of sex expression profiles obtained by the transcriptomic analysis, and demonstrated that most olfactory-related genes were specifically or primarily expressed in antennae, suggesting their roles in olfaction, while a few genes were highly expressed in other tissues, implying their non-olfaction functions. This study provides an important basis for further functional study of olfactory genes in M. loreyi .