Purpose To investigate the biosynthetic mechanism of benzylisoquinoline alkaloids (BIAs) in the medicinal plant Stephania epigaea, and to identify key regulatory genes, providing a theoretical basis for the biosynthesis of antiviral compounds.
Methods Different organs of the aboveground and underground parts of S. epigaea during flowering stage were collected as materials. Metabolomic and transcriptomic analysis were performed using ultra-performance liquid chromatography-tandem mass spectrometry and high-throughput RNA sequencing, respectively. Weighted gene co-expression network analysis (WGCNA) was employed to mine transcription factors (TFs) related to the BIA biosynthetic pathway, and the transcription levels of key genes were validated via qRT-PCR.
Results A total of 518 metabolites, including 86 alkaloids, were detected in the roots, stems, and flowers of S. epigaea. Transcriptomic and gene functional enrichment analysis revealed that differentially expressed genes were enriched in the isoquinoline alkaloid biosynthesis pathway. Combined with WGCNA, 80 TFs were screened for co-expression with 41 BIA synthase genes, among which, the myeloblastosis (MYB) gene family was the most abundant, followed by the NAC (NAM, ATAF1/2, and CUC2) family. qRT-PCR analysis showed that the expression of 10 BIA biosynthesis-related genes varied significantly across different organs, which was generally consistent with the transcriptomic trends.
Conclusion Five key genes (Sep12G014210|TYDC, Sep09G020110|TAT, Sep03G018560|TAT, Sep03G018950|TAT, and Sep10G011210|CYPN3) involved in the BIA biosynthetic pathway are discovered, initially revealing the biological basis for the synthesis of BIAs in S. epigaea.
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