Investigating the Regulation of Hypopharyngeal Gland Activity in Honeybees Under Nutrition and Brood Pheromone Conditions through RNA-seq Transcriptomics

The hypopharyngeal gland (HG) is the main site of the synthesis and secretion of royal jelly protein (RJP), and shows high plasticity. To identify differentially expressed genes (DEGs) that affect the development of HG and the synthesis and secretion of RJP, we performed a digital gene expression analysis of 9 d Apis mellifera under different conditions of nutrition and exposure to brood pheromone.Six RNA-seq libraries were generated using RNA extracted from 9 d bee HGs. A total of 2801 DEGs were identified on the basis of at least one pairwise comparison, among which 205, 1617 and 2328 genes were differentially expressed in comparisons between the Pollen group and the Honey group, the Brood group and Pollen group and the Brood group and Honey group respectively. The Brood group exhibited the highest number of DEGs, suggesting that brood pheromone plays a key role in the HG ontogeny. A total of 1991 genes were mapped to 129 canonical signaling pathways found in the Kyoto Encyclopedia of Genes and Genomes (KEGG), and the pathways associated with ribosome function and protein processing were significantly enriched. Overall design: Hypopharyngeal gland mRNA profiles of 9-day old honeybees under three conditions (one control and two treatments) were generated by deep sequencing, in duplicate, using Illumina Hiseq 2500 platform.

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