title: UPLC/Q-TOF MS-based metabolomics and qRT-PCR in enzyme gene screening with key role in triterpenoid saponin biosynthesis of Polygala tenuifolia.
abstract: BACKGROUND
  The dried root of Polygala tenuifolia, named Radix Polygalae, is a well-known traditional Chinese medicine. Triterpenoid saponins are some of the most important components of Radix Polygalae extracts and are widely studied because of their valuable pharmacological properties. However, the relationship between gene expression and triterpenoid saponin biosynthesis in P. tenuifolia is unclear.
  
  
  RESULTS
  In this study, ultra-performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (Q-TOF MS)-based metabolomic analysis was performed to identify and quantify the different chemical constituents of the roots, stems, leaves, and seeds of P. tenuifolia. A total of 22 marker compounds (VIP>1) were explored, and significant differences in all 7 triterpenoid saponins among the different tissues were found. We also observed an efficient reference gene GAPDH for different tissues in this plant and determined the expression level of some genes in the triterpenoid saponin biosynthetic pathway. Results showed that MVA pathway has more important functions in the triterpenoid saponin biosynthesis of P. tenuifolia. The expression levels of squalene synthase (SQS), squalene monooxygenase (SQE), and beta-amyrin synthase (β-AS) were highly correlated with the peak area intensity of triterpenoid saponins compared with data from UPLC/Q-TOF MS-based metabolomic analysis.
  
  
  CONCLUSIONS
  This finding suggested that a combination of UPLC/Q-TOF MS-based metabolomics and gene expression analysis can effectively elucidate the mechanism of triterpenoid saponin biosynthesis and can provide useful information on gene discovery. These findings can serve as a reference for using the overexpression of genes encoding for SQS, SQE, and/or β-AS to increase the triterpenoid saponin production of P. tenuifolia.
authors.affiliation: Modern Research Center for Traditional Chinese Medicine Shanxi University, Taiyuan, Shanxi, China.
authors.forename: Fusheng
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Modern Research Center for Traditional Chinese Medicine Shanxi University, Taiyuan, Shanxi, China; College of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, Shanxi, China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Li
authors.affiliation: Modern Research Center for Traditional Chinese Medicine Shanxi University, Taiyuan, Shanxi, China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Li
authors.affiliation: Modern Research Center for Traditional Chinese Medicine Shanxi University, Taiyuan, Shanxi, China; College of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, Shanxi, China.
authors.forename: Xiaoshuang
authors.initials: X
authors.lastname: Xu
authors.affiliation: Beijing Institute of Traditional Chinese Medicine, Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, Beijing, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Peng
authors.affiliation: Modern Research Center for Traditional Chinese Medicine Shanxi University, Taiyuan, Shanxi, China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Qin
authors.affiliation: Modern Research Center for Traditional Chinese Medicine Shanxi University, Taiyuan, Shanxi, China; Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Guanhua
authors.initials: G
authors.lastname: Du
mesh_terms: D005786:Gene Expression Regulation / Q000502:physiology*; D055432:Metabolomics; D031801:Polygala / Q000378:metabolism*; D012503:Saponins / Q000096:biosynthesis*; D014315:Triterpenes / Q000378:metabolism*
chemical_list: D012503:Saponins; D014315:Triterpenes