Strategies for increasing saikosaponins accumulation in Bupleurum: insights from environmental and microbial regulation.

Main conclusion: Suitable environments (low light, drought, adequate nutrients, moderate salinity, low temperature) and microorganisms (endophytic fungi, AMF, Trichoderma) promote saikosaponins accumulation by regulating key enzymes and transcription factors in biosynthetic pathways. Saikosaponins (SSs) are the principal bioactive constituents and crucial quality control markers in the genus Bupleurum. They possess diverse pharmacological activities, such as sedation, antipyretic, anticonvulsant, anti-inflammation, antitumor, antiviral, and hepatoprotection. The biosynthesis and accumulation of SSs are influenced by multiple factors, including abiotic environmental conditions (e.g., water, soil, light, and temperature) and microbial factors (such as endophytic fungi, mycorrhizal fungi, Trichoderma fungi and bacteria). Enzymes involved in SSs biosynthesis (e.g., HMGR, FPPS, IPPI, β-AS, P450, UGT) and transcription factors (e.g., ERF1-1, bHLH14, NAC53, WRKY6, WRKY16, WRKY32, WRKY40, etc.) play a key role in promoting the accumulation of SSs by these abiotic factors and microorganisms. This paper summarizes the regulation of SSs accumulation by environmental factors and microbial factors, aiming to provide a scientific basis for increasing SSs content in the genus Bupleurum and for formulating effective regulatory strategies to utilize high-quality medicinal materials.