Influence of RNA interference-mediated reduction of Or11 on the expression of transcription factor Kr-h1 in Apis mellifera drones

Abstract

9-Oxo-2-decenoic acid (9-ODA, the predominant component of honeybee queen mandibular pheromones) acts as a sex pheromone attracting drones during mating flights in midair. Odorant receptor 11 (Or11), which is located on the membrane of antennal olfaction receptor neurons in bees, can specifically recognize 9-ODA. At present, the molecular pathway of honeybee drones responding to 9-ODA is still unclear. Studies have demonstrated that 9-ODA could downregulate the expression of Kruppel-homolog1 (Kr-h1, a transcription factor related to the regulation of reproduction and division of labor mediated by juvenile hormone) gene in the mushroom of honeybee brain. We speculate that Kr-h1 may be the downstream gene of Or11, which is involved in the pathway of drones responding to 9-ODA. Therefore, we analyzed the influence of 9-ODA on the expression of Or11 and Kr-h1 in the antennae of sexually immature (4 days) and mature (14 days) male honeybees (Apis mellifera) by quantitative polymerase chain reaction (qPCR). The results demonstrated that 9-ODA significantly downregulated the expression of Or11 and Kr-h1 in the antennae of sexually immature and mature drones. Additionally, siRNA-Or11 was injected into the antennae and brain tissues of 8-day-old drone pupae, and the expression patterns of Or11, Kr-h1 and Broad-Complex (Br–c, downstream gene of Kr-h1) were determined by qPCR at 72 h. The RNAi-induced knockdown of Or11 significantly decreased the expression of Or11, Kr-h1 and Br–c in the antennae and brains of drones. This study suggests that the transcription factor Kr-h1 is downstream of Or11, Kr-h1, which may play an important role in the signal transduction process of drones responding to 9-ODA.