Effect of Developmental Stages on the Biosynthesis of Triterpene Saponins and Related Gene Expression in Seedlings of Platycodon grandiflorus

Abstract

Objective: To investigate the impact of developmental stages on triterpene saponin content and expression of key genes in their biosynthetic pathway in Platycodon grandiflorus seedlings. Method: The total saponins were extracted using ultrasonic extraction with methanol as the solvent. The quantification of Platycodin D in 6-month-old and 1-year-old Platycodon grandiflorus seedlings was performed using ultra-performance liquid chromatography tandem mass spectrometry, while the expression of key genes in the biosynthesis of saponins was determined by real-time quantitative polymerase chain reaction. Result: The content of Platycodin D and total saponins in 1-year-old Platycodon grandiflorus roots was significantly higher than that in of 6-month-old. The expression of key genes in saponin biosynthesis, such as PGMVK , PGMVD , PGDXR , PGMCT , PGMDS , PGHDS , PGHDR , PGFPS, and PGSS, was higher in 1-year-old roots compared to 6-month-old seedlings. Conclusion: The medicinal value of 1-year-old Platycodon grandiflorus root was higher than that of 6-month-old seedlings. The difference in medicinal value can be attributed to the variation in the expression of key genes involved in the saponin biosynthesis pathway.