Molecular characterization and differential expression of two duplicated dorant receptor genes, AcerOr1 and AcerOr3, in Apis cerana cerana

Insects use olfaction to recognize a wide range of volatile cues, to locate food sources, mates, hosts and oviposition sites. These chemical volatiles are perceived by odorant receptors (ORs) expressed on the dendritic membrane of olfactory neurons, most of which are housed within the chemosensilla of antennae. Most insect ORs are tandemly arrayed on chromosomes and some of them are formed by gene duplication. Here, we identified a pair of duplicated Or genes, AcerOr1 and AcerOr3, from the antennae of the Asian honeybee, Apis cerana cerana, and reported their molecular characterization and temporal expression profiles. The results showed that these two genes shared high similarity both in sequence and the gene structure. Quantitative real-time PCR analysis of temporal expression pattern indicated that in drones the expression pattern of these two genes were very similar. The transcripts expressed weakly in larvae and pupae, then increased gradually in adults. In workers, the expression level of AcerOr1 changed more drastically and expressed higher than that of AcerOr3. However, both reached their highest expression level in one-day-old adults. In addition, the expression profiles between different sexes revealed that AcerOr3 appear to be expressed biased in male antennae. These results suggest that AcerOr1 may perceive odours of floral scents, while AcerOr3 may detect odours critical to male behaviour, such as the queen substance cues.