Dynamic changes in terpenoids metabolisms of mountain-cultivated ginseng harvested at different months and ages

The quality of mountain-cultivated ginseng (Panax ginseng Meyer; MCG) was closely related to the terpenoids metabolism which was significantly affected by harvest months and cultivation years. In this study, the metabolisms of terpenoids and carbohydrates in the MCG harvested at different months and cultivation years were elucidated using a transcriptomic approach. Based on the RNA-Seq analysis, 42 and 41 genes related to terpenoids metabolism were identified in the MCG of different harvest months (August, September, and October) and cultivation years (5, 10, and 15 years), respectively. In August, the biosyntheses of terpineol, valencene, germacrene, solavetivone, and brassinolide were more active, and those of valencene and brassinolide were less active than in September and October, while those of gibberellin (GA), campesterol, and strigol gradually became active from September through October in the 10 years' MCG. Terpenoids metabolisms in MCG were repressed in October, except for the biosyntheses of neomenthol, stigmasterol, and abscisic acid. Besides, one of the reasons why MCG does not like high temperature or is not suitable for high temperature survival were explained. By comparing the difference in terpenoids metabolism in MCG harvested in September) of different cultivation years, it was found that the biosyntheses of neomenthol, germacrene, GA, and brassinolide were more active in the 5th year. In the 10th year, only the biosyntheses of terpineol, solavetivone, and campesterol were activated. Surprisingly, all these pathways associated with terpenoids metabolisms became inhibited at the 15th year. In addition, in the process of carbohydrates metabolisms, the growth environment has greater influence, whereas there is little correlation between cultivation years and carbohydrates metabolisms. These findings will deepen our understanding of the complicated but important biosynthesis and regulation of terpenoids in the plant species.