Potential participants and regulatory factors in ginsenoside biosynthesis of Panax ginseng C.A. Meyer: The role of endophytic fungus PBF-08

Panax ginseng C.A. Meyer was recognized as a precious traditional Chinese medicine with a long history of application. It is widely used due to its high medicinal value. Ginsenosides were identified as a group of triterpenoid secondary metabolites in ginseng and were considered the main active ingredients of ginseng. Plant endophytes were recognized as microorganisms that resided within plant tissues, coexisting with the host plant for part or all of their life cycle and interacting with the external environment together. Ginseng endophytes, as symbiotic microorganisms with ginseng, possess various functions such as enhancing yield, increasing resistance, and improving quality, making them an important microbial resource for potential utilization. In this study, we screened and identified an endophytic fungus PBF-08, which has the ability to produce ginsenosides Rg2, Rg3, and Re. By optimizing its fermentation conditions using the response surface methodology, the total ginsenoside yield was significantly increased. Additionally, ginseng adventitious roots were treated with strain PBF-08 as an elicitor, which significantly increased the ginsenoside content by regulating the expression of key enzyme genes in the ginsenoside biosynthesis pathway under optimal treatment concentration and time. Widely targeted metabolomic analysis revealed that strain PBF-08 not only possesses a complete and active terpenoid biosynthesis pathway but also synthesizes various metabolites that influence plant growth and metabolism. In summary, the strain PBF-08 was found to have potential application value in exploring new methods for obtaining ginsenosides and in developing microbial elicitors for regulating ginsenoside biosynthesis.