Omics map of bioactive constituents in Lonicera japonica flowers under salt stress

Lonicera japonica flowers (LJF) is a member of the Caprifoliaceae family and is used in traditional Chinese medicine (TCM). There is growing evidence that moderate salinity can stimulate the accumulation of bioactive constituents in LJF; however, the molecular mechanism underlying this accumulation remains unclear. In this study, a quantitative proteomic analysis of LJF after salt stress for 35 days was performed, and differentially expressed proteins (DEPs) in LJF during salt stress were mapped. Protein-protein interaction (PPI) networks based on DEPs in LJF during salt stress showed that energy metabolism and carbohydrate metabolism were the top items in terms of biological function. In addition, the expression of genes involved in phenylpropanoid, flavonoid, and iridoid synthesis was mostly upregulated, albeit dynamically, under salt stress. Furthermore, the associated protein expression was essentially consistent with the trends of the main bioactive constituent profiles in LJF during salt stress. Finally, parallel reaction monitoring (PRM) was performed to validate the abundance of candidate proteins. Overall, this study provided novel clues into the research of secondary metabolite synthesis in LJF in response to salt stress.