RNA sequencing of antennae and comparative analysis of key gene families in Apis mellifera workers exhibiting drastic differences in propolis yield

Background Propolis is a composite substance that Apis mellifera worker bees produce from plant resins they collect and blend with their own secretions. The antennae detect signals from nectar, pollen, and propolis sources during the foraging process, thereby regulating foraging behavior. However, the relationship between resin collection behavior and olfaction in worker bees from different colonies remains unclear. We compared the antennal morphology and RNA-seq profiles of foragers from high propolis-producing and ordinary colonies of A. mellifera worker bees, comprehensively characterized three gene families (OBPs, CSPs, and ORs), and validated expression patterns by qRT-PCR. Results We found that the total length of both the left and right antennae, as well as the lengths of flagellomeres FL7 and FL10, were significantly shorter in high-yield colonies than in ordinary colonies. We analyzed the FPKM heatmaps, chromosomal locations, and conserved domains of six CSPs, 19 OBPs, and 34 ORs, and performed phylogenetic analyses with Apis cerana , Chouioia cunea , Nasonia vitripennis , and Bombus . qRT-PCR expression levels of these 58 genes were consistent with the RNA-seq expression patterns. We report for the first time the differences in antennal morphology and RNA-seq results between colonies with differential propolis yield, as well as differences in gene expression of these three gene families between the two colony types. Conclusions Results not only provide a molecular basis for further research into how worker bee antennae function in honeybee colonies, but also offer new perspectives on the molecular mechanisms underlying the interaction between worker bee behavioral differentiation and the olfactory system.