Identification and expression profiles of candidate chemoreceptor genes in the tea leafhopper, Empoasca onukii Matsuda (Hemiptera: Cicadellidae).

The olfactory system of insects regulates the processes of insect feeding, mating, and egg laying through the participation of various olfactory proteins, hence it plays a key role in insect survival and reproduction. The tea leafhopper, Empoasca onukii Matsuda, is one of the most devastating pests in Chinese tea plantations. Transcriptome sequencing experiments were conducted to detect chemoreceptor genes including odorant receptors/co-receptors (ORs/Orco), ionotropic receptors (IRs), N-methyl-D-aspartic acid receptors (NMDAs), gustatory receptors (GRs), and sensory neuron membrane proteins (SNMPs). Phylogenetic analysis of chemoreceptor genes and the expression levels of the identified genes in four different tissues of E. onukii, including antennae, heads, bodies, and legs were also analyzed. In total, 12 ORs, five IRs, three NMDAs, three GRs, and two SNMPs were annotated in the E. onukii transcriptome data. The number of chemoreceptor genes in E. onukii was considerably lower than that in other hemiptera insects. Phylogenetic analysis was conducted to compare ORs, IRs, NMDAs, GRs, and SNMPs among the hemiptera insects, and showed that chemoreceptor genes in E.onukii were clustered into ten clades with other hemiptera insects, respectively. The results of RT-qPCR showed that seven EonuORs, three EonuIRs, and one EonuGRs were highly expressed in the antennae of E. onukii. The function of chemoreceptor genes in E. onukii in sensing the volatile compounds remains to be elucidated. [ABSTRACT FROM AUTHOR]