Involvement of miRNAs regulation on both flower development and secondary metabolism in Lonicera japonica Thunb.

Lonicera japonica Thunb. is a famous healthy resource of both medicine and food. The flower of L. japonica is widely used in health tea and beverages industries. Although the accumulation mechanism of active ingredients during the flowering process has attracted numerous studies, the regulatory function of miRNAs, at post transcriptional modification level, has not been deeply investigated. In this study, miRNAs from floral stages were sequenced and functionally analyzed by means of obtained transcriptomic and metabolomic data. Totally 234 differentially expressed miRNAs were identified and significant expression correlation was observed between 182 target genes and 83 associated miRNAs. The constructed correlation network demonstrated Car-miRN777 might perform broad regulation effects on RNA, protein, lipid metabolism, transport, and secondary metabolism. The target genes belonging to RNAs showed a gradual decrease during the flower development. It was further proved that Car-miRN777 and miR319a targeted ELF7/CPK33 and MYB33/TCP4, respectively, regulating the flowering process. Additionally, miR160I and miR482d targeting ADT and MYB1, respectively, might mediate the upstream and downstream fluxes of phenylalanine for anthocyanin formation. Taken together, this study identified potential miRNAs regulating flowering process and secondary metabolic accumulation during floral stages, which could promote the industrial development of high-quality food resources of L. japonica.