Metabolome and transcriptome analyses reveal the colouring mechanism of red honeysuckle (Lonicera japonica Thunb.)

Abstract

Honeysuckle has been widely used as a medicinal herb and food additive in China for a long time. However, little is known about the pigment composition and colouring mechanism of red honeysuckle, which is a rare germplasm resource. This study aims to investigate the anthocyanin components and colouring mechanism of red honeysuckle, and to identify potential regulatory genes in the anthocyanin biosynthesis pathway. ‘Yujin 1’ and ‘Yujin 2’, with yellow-white and red flower buds, respectively, were selected for the study. Using a metabolomics method, we identified the anthocyanin components, while transcriptomics analysis was used to mine the structural and regulatory genes of the anthocyanin biosynthesis pathway. Additionally, protein-protein interaction analysis was employed to predict the regulation mechanism of anthocyanin biosynthesis. The results revealed that cyanidin-3,5-O-diglucoside, peonidin-3,5-O-diglucoside, and cyanidin-3-O-glucoside were the main pigment components of red honeysuckle. We also constructed a possible anthocyanin biosynthetic pathway and identified MYB and bHLH transcription factors that may play regulatory roles in this pathway. Furthermore, our findings suggest that bHLH23 may regulate anthocyanin biosynthesis by binding to the DFR gene promoter. These findings have significant implications for breeding new honeysuckle varieties and developing functional foods and medicines.