Medicinal Plant Research 2025, Vol.15, No.6, 264-273 http://hortherbpublisher.com/index.php/mpr 267 aglycone forms, as in converting scopolin into scopoletin in other related Angelica species (Han et al. 2022; Wang et al., 2024; 2025) (Figure 2). CoA-dependent processes are required for hydroxycinnamic acid activation in order to enable further modifications and the assembly of the coumarin backbone (Roy et al., 2016; Xu et al., 2019). Figure 2 Cumarin biosynthesis inAngelica sinensis (Adopted from Han et al., 2022) 3.4 Downstream modifications and structural diversification Through hydroxylation by CYPs, methylation by COMT/CCoAOMT, glycosylation mediated by UDP-glycosyltransferases, and acylation, the structural diversification of phenylpropanoids is achieved. More specifically, glycosylation controls solubility, stability, and biological activity and hence is one of the major regulatory points for phenylpropanoid homeostasis (Roy et al., 2016). Various such modifications contribute to coumarin, flavonoid, and lignin diversity in A. sinensis (Xu et al., 2019; Li et al., 2023). 3.5 Interactions and metabolic flux partitioning between polyphenols and coumarins Metabolic flux of the phenylpropanoid pathway is branched in different directions, partitioned between polyphenols, including flavonoids and lignins, and coumarins. Partitioning of metabolic flux is influenced by pathway gene expression and regulatory factors, in addition to environmental and developmental cues. As such, higher expression of PAL, C3H, and CQT in root tails favors ferulic acid and coumarin biosynthesis, whereas methylation status can shift flux toward either lignin or coumarin production (Xu et al., 2019; Li et al., 2023). Gene family expansions and transcriptional regulation are at the heart of this metabolic flexibility, as highlighted by multi-omics analyses (Han et al., 2022). 4 Genes and Regulatory Networks in Phenylpropanoid Biosynthesis of Angelica sinensis 4.1 Identified key genes The key genes in the phenylpropanoid biosynthesis pathway of A. sinensis are PAL, 4CL, HCT, and several members of the CYP450 family. Multi-omics and transcriptomic studies on these enzymes also revealed that most of them have multiple isoforms and gene copies, among which PAL, C3H, and CQT exhibit high expression in root tails to promote the biosynthesis of ferulic acid and coumarin (Xu et al., 2019; Yang et al., 2020; Li et al., 2023). The expansion of other gene families, such as PTs and CYPs, also supported the metabolic diversity in A. sinensis (Han et al., 2022; Li et al., 2023). 4.2 Transcription factors These include MYB, bHLH, WRKY, and AP2/ERF transcription factor families, which have been identified as playing basic roles in the transcriptional activation of genes in the phenylpropanoid pathway. The R2R3-MYB TFs are considered master regulators that regulate the transcription of structural genes responsible for flavonoid, anthocyanin, and lignin biosynthesis (Du et al., 2022). MYB3 was identified to be a key regulator of flavonoid and anthocyanin synthesis in coexpression network analyses with positive correlation to key biosynthetic enzymes
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