Transcriptomics and targeted metabolomics profilings for elucidation of pigmentation in Lonicera japonica flowers at different developmental stages

Abstract To explore the molecular and metabolic bases of pigmentation in Lonicera japonica flowers at different developmental stages, we profiled the transcriptome at six developmental stages (S1–S6) and constructed regulatory networks of anthocyanin biosynthesis, chlorophyll metabolism, and carotenoid biosynthesis by weighted gene co-expression network analysis (WGCNA). The transcriptomics results demonstrated that the early flower colors were caused by anthocyanins and chlorophylls, and the late golden flower (S6) by carotenoids rather than anthocyanins. To identify the carotenoids responsible for the golden flowers, targeted metabolomics profiling of the flowers at S1, S4, and S6 was performed. The results showed that the golden flowers contained the highest contents of 11 of the 14 detectable carotenoids, and the total content of α-carotene, γ-carotene, and zeaxanthin accounted for 79.6% of the content of the 13 carotenoids detected at S6, indicating that they are major contributors to the golden flowers.