Differential transcriptome analysis and functional validation of genes associated with the biosynthesis of paeoniflorin in tree peony (Paeonia suffruticosa Andr.).

Tree peony (Paeonia suffruticosa Andr.), known as a woody plant of the genus paeonia in the peony family, is widely cultivated for ornamental and medicinal purposes. In tree peony, its roots have high medicinal values, and a number of active ingredients can be found in the root bark. Among those ingredients, paeoniflorin is of the greatest valuable medicinal ingredient. While there is still no understanding of the gene regulatory pathways on the production of paeoniflorin. In this study, three varieties of tree peony with different paeoniflorin content levels were selected as the experimental materials, and their root transcriptomic comparative analysis were conducted. Through transcriptome sequencing analysis, we identified 114,043 genes, belonging to 34 transcription factor families. By differential gene analysis and functional gene annotation, PsMVK, which encodes a key biosynthetic enzyme of paeoniflorin, was chosen and identified. Its function was verified by virus induced gene silencing (VIGS) assay in both roots and leaves. In addition, it was evidenced that the expression levels of PsMVK was positively correlated with paeoniflorin content. Therefore, this study would be useful in providing genetic resources and theorizing about paeoniflorin metabolism.