Identification of putative odorant binding proteins in the peach fruit borer Carposina sasakii Matsumura (Lepidoptera: Carposinidae) by transcriptome analysis and their expression profile

Abstract

The peach fruit borers Carposina sasakii Matsumura (Lepidoptera: Carposinidae) are serious fruit borers in East Asia. Odorants have been reported to elicit their olfactory responses, including sex pheromone and host plant volatiles. However, little is known about their molecular aspects of olfactory perception to these odorants. Odorant binding proteins (OBPs) are believed to play an important role in insect olfaction, which recognize and bind odorants, and transport them to odorant receptors located on olfactory neurons. We identified 12 putative OBPs (CsasOBP1-12) expressed in intact heads (with antennae and mouthparts) of C. sasakii adult males and females by transcriptome analysis, including 4 putative pheromone binding proteins (PBPs) (CsasOBP1-2, 7, 11) and 4 putative general odorant binding proteins (GOBPs) (CsasOBP6, 9–10, 12). A phylogenetic tree was constructed to characterize these OBPs. An analysis using fluorescence quantitative PCR showed that CsasOBP3, 5, 7, 9–12 have the highest expression level in the intact heads, suggesting that among them there may be the OBPs playing key roles in C. sasakii olfaction. In the 7 OBPs, CsasOBP5, 7, 11–12 have higher level of expressions in intact heads of C. sasakii adult males than females, while CsasOBP3, 9–10 are expressed equally in the two sexes. Moreover, CsasOBP2 is expressed dominantly in the intact heads and wings, with an equal level between them. CsasOBP8 expression is highest in the wings, while CsasOBP1, 4, 6 are expressed dominantly in the abdomens. Our study is helpful for understanding C. sasakii OBPs’ functions and C. sasakii olfaction from molecular view.