Molecular Mechanisms Underlying Ginsenosides Biosynthesis: Genome-Wide Cloning and Analysis of Genes Involved in Ginsenoside Biosynthesis from Jilin Ginseng, Panax ginseng C.A. Meyer

Ginsenosides are the major components of ginseng that function in human medicine. Although this has been known for years, few genes involved in ginsenosides biosynthesis have been cloned. Here we have cloned 312 genes involved in the ginsenosides biosynthesis from Jilin ginseng using a genome-wide high-throughput gene cloning system and investigated its underlying molecular mechanism by analysis of the cloned genes. These genes were defined as “PgiTS” for Panax ginseng Total Saponins. Of the 312 PgiTS genes, 295 (94.6%) were shared with those involved in the biosynthesis of nine of the monomer saponins. These genes have an effect on total saponins contents in roots varying from 15.2% – 57.3%, of which 166 increased while 146 decreased the contents of total saponins when turned on or up-regulated. Annotation allowed that 126 (40.4%) of the genes were assigned to known proteins or enzymes involved in a variety of biochemical reactions. These annotated genes were categorized into 17 functional categories (Level 2), with seven in Cellular Components, eight in Biological Process and two in Molecular Function. Of the 126 annotated PgiTS genes, 122 were mapped to 55 metabolic pathways, including the pathways of terpenoid biosynthesis. Network analysis showed that the 312 PgiTS genes functioned collaboratively and formed a co-expression network consisting of 312 nodes and 20,533 edges (P ≤ 0.01). These cloned PgiTS genes and novel knowledge of ginsenosides biosynthesis shed great light on ginseng improvement and applications of the process of ginsenoside biosynthesis in agriculture and fermentation industry.