Methyl Jasmonate Enhances Saponin Accumulation in Cultured Panax notoginseng Adventitious Roots

<i>Panax notoginseng</i> is a valuable medicinal herb, but its sustainable production is constrained by long cultivation cycles and continuous cropping obstacles. Adventitious root culture presents a viable alternative. This study establishes a robust and sustainable platform for the efficient production of ginsenosides in <i>P. notoginseng</i> adventitious root cultures. We first systematically optimized the culture system, identifying leaf segments as the optimal explant due to their high callus induction rate (95.77%), low contamination, and renewable nature. Combined with optimized bioprocess parameters (3 g/L inoculation density, 50 g/L sucrose), this strategy addressed key practical bottlenecks. Beyond methodological advancement, our research provides novel mechanistic insights into the action of methyl jasmonate (MeJA). A key finding is the discovery that MeJA functions as a 'precision metabolic switch,' differentially regulating a critical branch point in the saponin pathway. It coordinately upregulates the protopanaxadiol (PPD)-type gene <i>CYP716A47</i> while downregulating the protopanaxatriol (PPT)-type gene <i>CYP716A53v2</i> that genetically explains the directed enrichment of specific ginsenosides. This integrated approach not only advances the fundamental understanding of elicitor action but also provides a scalable and controllable system for the industrial production of <i>P. notoginseng</i> phytopharmaceuticals with tailored saponin profiles.