Protein baits, volatile compounds and irradiation influence the expression profiles of odorant-binding protein genes in Bactrocera dorsalis (Diptera: Tephritidae)

Abstract

Chemical communication in insects is based on odorant-binding proteins (OBPs), but the molecular mechanisms by which these OBPs allow the perception of volatiles and host chemicals remain unclear. Bactrocera dorsalis (Hendel) is one of the most economically important pests of fruits and vegetables. In this study, the OBPs of B. dorsalis (BdorOBPs) were evaluated in response to different attractive protein baits, brewer’s yeast volatile compounds and irradiation. The expression of 10 genes encoding OBPs in the antennae of B. dorsalis during three adult physiological life stages (pre-mating, post-mating and post-oviposition) were analysed. All selected BdorOBP genes were found to contain one conserved pheromone-binding protein/general-odorant-binding protein domain (PBP-GOBP), except OBP8, which contained two of these conserved domains. An unrooted phylogenetic tree was constructed to show the relationships among these 10 BdorOBPs and the OBPs belonging to the same OBP family in other insects. We found significantly different transcript expression profiles in each OBP gene at each stage in response to different treatments; these results revealed that OBP2 expression was significantly increased in response to baits at each adult physiological stage, while OBP2, OBP5 and OBP1 were highly expressed in response to combined-volatiles treatment at all tested physiological stages. OBP3, OBP5 and OBP10 showed high expression in response to irradiation at all tested physiological stages. Thus, we infer that protein baits, brewer’s yeast volatiles and irradiation significantly influence the transcript levels of OBP genes, which may act in olfactory perception.