Integrated Metabolomic and Transcriptomic Analysis Reveals Differential Mechanism of Flavonoid Biosynthesis in Two Cultivars of Angelica sinensis.

Tiantian Zhu,Mengfei Li,Minghui Zhang,Hongyan Su,Meiling Li,Ling Jin,Yuanyuan Wang

doi:10.3390/molecules27010306

Abstract

Angelica sinensis is a traditional Chinese medicinal plant that has been primarily used as a blood tonic. It largely relies on its bioactive metabolites, which include ferulic acid, volatile oils, polysaccharides and flavonoids. In order to improve the yield and quality of A. sinensis, the two cultivars Mingui 1 (M1), with a purple stem, and Mingui 2 (M2), with a green stem, have been selected in the field. Although a higher root yield and ferulic acid content in M1 than M2 has been observed, the differences of flavonoid biosynthesis and stem-color formation are still limited. In this study, the contents of flavonoids and anthocyanins were determined by spectrophotometer, the differences of flavonoids and transcripts in M1 and M2 were conducted by metabolomic and transcriptomic analysis, and the expression level of candidate genes was validated by qRT-PCR. The results showed that the contents of flavonoids and anthocyanins were 1.5- and 2.6-fold greater in M1 than M2, respectively. A total of 26 differentially accumulated flavonoids (DAFs) with 19 up-regulated (UR) and seven down-regulated (DR) were obtained from the 131 identified flavonoids (e.g., flavonols, flavonoid, isoflavones, and anthocyanins) in M1 vs. M2. A total 2210 differentially expressed genes (DEGs) were obtained from the 34,528 full-length isoforms in M1 vs. M2, and 29 DEGs with 24 UR and 5 DR were identified to be involved in flavonoid biosynthesis, with 25 genes (e.g., CHS1, CHI3, F3H, DFR, ANS, CYPs and UGTs) mapped on the flavonoid biosynthetic pathway and four genes (e.g., RL1, RL6, MYB90 and MYB114) belonging to transcription factors. The differential accumulation level of flavonoids is coherent with the expression level of candidate genes. Finally, the network of DAFs regulated by DEGs was proposed. These findings will provide references for flavonoid production and cultivars selection of A. sinensis.

Highlights

We examined the differences of flavonoids and transcripts based on metabolomic and transcriptomic analysis, and found that the flavonoid and anthocyanin contents were greater in Mingui 1 (M1) than Mingui 2 (M2); 26 flavonoids were differentially accumulated; and 29 genes involved in flavonoid biosynthesis were differentially expressed in M1 vs. M2
26 (19 UR and 7 DR) flavonoids that were differentially accumulated in M1 vs. M2 based on the principal component analysis (PCA) and orthogonal projection to latent structures-discriminant analysis (OPLS-DA) (Figures S1 and S2)
The specific flavonoids and their differential accumulation levels in M1 vs. M2 are shown in Table 1 and Figure S3

Summary

Introduction

Umbelliferae) perennial rhizomatous species and commonly named as Dang gui, Dong quai and Toki [1]. The species is originally native to China, with a population center in Gansu and widely cultivated at altitudes of 2000 to 3000 m [1,2,3]. The roots were first recorded in the earliest known herbal text “Shen Nong Ben Cao Jing”, and have been used as a traditional Chinese medicine for nourishing the blood, regulating female menstrual disorders, relieving pain, and relaxing the bowels, etc., for over 2000 years [4,5]. The roots have been used as potential treatments of acute ischemic stroke, chronic obstructive pulmonary disease with pulmonary hypertension, as well as for its cardiocerebrovascular, immunomodulatory and antioxidant effects [5,6,7]. Phytochemical and pharmacological investigations have demonstrated that these therapeutic properties largely rely on bioactive metabolites including ferulic acid, volatile oils, polysaccharides and flavonoids [1,5,8]

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Results

Conclusion