Identification of the genes in tea leafhopper, Empoasca onukii (Hemiptera: Cicadellidae), that encode odorant-binding proteins and chemosensory proteins using transcriptome analyses of insect heads

Empoasca onukii Matsuda is a serious pest affecting tea production throughout China. Chemosensory behaviors are important in the life cycle of E. onukii, especially for detecting plant odorants during host localizations. In this process, odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) mediate the initial biochemical recognition steps. We used a transcriptomics-based approach to identify 40 putative E. onukii OBP genes and 11 CSP genes. The encoded OBPs comprised 19 classic OBPs and 21 plus-C OBPs. A phylogenetic analysis revealed that the plus-C OBPs formed monophyletic groups, and most of the classic OBPs and CSPs were distributed among other orthologous groups. Additionally, there were significant differences between the sexes regarding the expression of five OBP genes and two CSP genes. Moreover, 36 OBP genes and six CSP genes were most highly expressed in the heads. Two CSP genes were most highly expressed in the thoraxes, while four OBP genes and three CSP genes exhibited high expression levels in the heads and thoraxes. Our data may represent a valuable resource for future functional characterizations of the E. onukii OBPs and CSPs.