Biochemical and molecular analysis of Ginsenoside biosynthesis in Panax ginseng during flower and berry development

Abstract

Panax ginseng produces a large number of ginsenosides throughout the parts of the ginseng plant. Several genes in the ginsenoside biosynthesis pathway were cloned, including those encoding farnesyl diphosphate synthase, squalene synthase, squalene epoxidase, dammarenediol-II synthase, lanosterol synthase, β- amyrin synthase, and cycloartenol synthase. The expression levels of these seven genes were examined in the roots and different developmental stages of the flowers and berries of 4-year-old ginseng plants using quantitative real-time polymerase chain reaction. The levels of ten ginsenosides (Rb1, Rb2, Rb3, Rc, Rd, Re, Rf, Rg1, Rg2, and Rh1) were determined by high performance liquid chromatography analysis. Gene expression varied during flower and berry development. Total saponin levels were highest in the early berry stage and correlated well with those in the ginseng root. Therefore, berries should be harvested at the early berry stage to ensure optimal ginsenoside levels for pharmaceutical interest.