Novel aspects of understanding molecular working mechanisms of salivary glands of worker honeybees (Apis mellifera) investigated by proteomics and phosphoproteomics.

Unlabelled: Honeybee salivary glands (SGs) are important exocrine glands. However, the molecular basis of how SGs fulfill their biological duty is still elusive. Proteomics and phosphoproteomics of cephalic SG (HSG) and thoracic SG (TSG) were compared between normal and single-cohort honeybee colonies. Of 113 and 64 differentially regulated proteins and phosphoproteins, 86 and 33 were identified, respectively. The SGs require a wide spectrum of proteins to support their multifaceted functions and ensure normal social management of the colony. Changes of protein expression and phosphoproteins are key role players. The HSG triggers labor transition from in-hive work to foraging activities via the regulation of juvenile hormone and ethyl oleate levels. The stronger expression of proteins involved in carbohydrate and energy metabolism, protein folding, protein metabolism, cellular homeostasis and cytoskeleton in TSG, supports the gland to efficiently enhance honey processing by synthesis and secretion of saliva into nectar. The age structure of the colony is vital for increased production efficiency. This data reveals the molecular underpinning of SGs to accomplish their biological missions and provides new knowledge for the beekeeping industry for enhancing the management and production efficiency of the colony and honey quality through manipulation of potential target proteins.

Biological Significance: This study comprehensively analyses the characteristic of the proteome and phosphoproteome of honeybee salivary glands (SGs) between normal and single-cohort honeybee colonies. The SGs need a wide spectrum of proteins to support their multifaceted functions and ensure normal social management of the colony. The cephalic SG triggers labor transition from in-hive work to foraging behavior via the regulation of juvenile hormone and ethyl oleate titer. The thoracic SG stronger expressed of proteins related to carbohydrate and energy metabolism, protein folding, protein metabolism, cellular homeostasis and cytoskeleton to support the gland to efficiently enhance honey processing by synthesis and secretion of saliva into nectar. This data reveals the molecular underpinning of SGs to accomplish their biological missions and provides new knowledge for the beekeeping industry for enhancing the maintenance and production efficiency of the colony and honey quality through manipulation of potential target proteins.