Integrated metabolomic and transcriptomic analyses of flavonoid accumulation in different cultivars of Platostoma palustre.

backgroundPlatostoma palustre is a kind of plant resource with medicinal and food value, which has been differentiated into many different varieties after a long period of breeding. The cultivars of Taiwan(TW) and Pingyuan(PY) are widely grown in Guangdong, but a clear basis for species differentiation has not yet been established, resulting in the mixing of different species which limits their production and application.

resultsRegarding leaf surface morphology, the TW exhibited greater leaf area, non-glandular hairs, and the number of stomata than the PY. Regarding chemical activities, the TW exhibited higher total flavonoid content and antioxidant activity than the PY. In metabolomics, a total of 85 DAMs were detected, among which four flavonoid DAMs were identified, all of which were up-regulated in TW expression. Transcriptome analysis identified 2503 DEGs, which were classified according to their functional roles. The results demonstrated that the DEGs were primarily involved in amino acid metabolism, carbohydrate metabolism, sorting and degradation. A total 536 transcription factors (TFs) were identified, of which bHLH and MYB were the top two most abundant TFs families. Combined analysis of metabolome and transcriptome indicated that the phenylpropanoid pathway plays a significant role in flavonoid synthesis. Furthermore, real-time fluorescence qrt-PCR validation demonstrated that the expression trend of 10 DEGs was consistent with the transcriptomics data.

conclusionThe phenylpropanoid pathway affects the synthesis of secondary metabolites, resulting in functional differences. In this study, metabolomic and transcriptomic analyses were performed to elucidate the regulatory mechanisms of flavonoid synthesis in P. palustre and to provide a theoretical basis for the identification, differentiation and breeding cultivation of different cultivars of P. palustre.