Sex Differences in Antennal Transcriptome of Hyphantria cunea and Analysis of Odorant Receptor Expression Profiles

Abstract

Insects rely on olfaction for mating, finding oviposition sites, and locating hosts. Hyphantria cunea is a serious pest that severely damages forests. Differential expression analysis of olfactory-related genes between males and females is the basis for elucidating the functions of olfactory-related proteins in H. cunea. In this study, Illumina HiSeqTM 4000 high-throughput sequencing technology was used to perform transcriptome sequencing of the antennal tissues of adult male and female H. cunea. Functional annotation was conducted using the NR, Swiss-Prot, KOG, KEGG, and GO databases, and the results showed that the antennal transcriptome of adult H. cunea contained 50,158 unigenes. Differential expression analysis identified 3923 genes that were significantly differentially expressed between male and female antennae. A total of 221 olfactory-related genes were annotated, and 96 sex-biased genes were identified, including 13 odorant receptors (ORs), 48 odorant binding proteins (OBPs), 7 chemosensory proteins (CSPs), 10 ionotropic receptors (IRs), 10 sensory neuron membrane proteins (SNMPs), 2 gustatory receptors (GRs), and 6 odorant-degrading enzymes (ODEs), indicating that there were differences in olfaction between male and female H. cunea. Quantitative real-time PCR was used to verify the expression levels of 21 putative general odorant receptor genes in male and female antennae. HcunOR4 and HcunOR5 showed female-biased expression; HcunOR48, HcunOR49 and HcunOR50 showed male-biased expression. The results were consistent with the transcriptome differential analysis. The screening of male-biased odorant receptor genes might provide a theoretical basis for the functional characterization of odorant receptors for recognizing sex pheromones in H. cunea.

Keywords: Hyphantria cunea; antennal transcriptome; odorant receptor expression level; sex difference.

Figure 1

Sample relationship analysis. (A) Principal component analysis between female and male antennae samples; (B) correlation analysis of individual biological replicates in males and females; (C) hierarchical clustering between biological replicates of male and female antennae tissues.

Figure 2

(A) Differential gene statistical map. (B) The volcano map of genes for sex difference of H. cunea (female vs. male); the dark blue dots are OR genes with significant DGE. The dashed lines mean FDR < 0.05 or |log2FC| > 1. (C) DGE heat map for gene expression clustering.

Figure 3

GO enrichment bubble plot of the antennal transcriptome of H. cunea (females vs. males).

Figure 4

KO enrichment bubble plot of antennal transcriptome of H. cunea (female vs. male).

Figure 5

PPI network of DGE olfactory receptor genes.

Figure 6

Expression profiles of general odorant receptors in the antennae of male and female H. cunea by qRT-PCR. **: p < 0.01, *: p < 0.05, n.s.: no significant difference.