title: Alteration of Panax ginseng saponin composition by overexpression and RNA interference of the protopanaxadiol 6-hydroxylase gene (CYP716A53v2).
abstract: BACKGROUND
  The roots of Panax ginseng contain noble tetracyclic triterpenoid saponins derived from dammarenediol-II. Dammarene-type ginsenosides are classified into the protopanaxadiol (PPD) and protopanaxatriol (PPT) groups based on their triterpene aglycone structures. Two cytochrome P450 (CYP) genes (CYP716A47 and CYP716A53v2) are critical for the production of PPD and PPT aglycones, respectively. CYP716A53v2 is a protopanaxadiol 6-hydroxylase that catalyzes PPT production from PPD in P. ginseng.
  
  
  METHODS
  We constructed transgenic P. ginseng lines overexpressing or silencing (via RNA interference) the CYP716A53v2 gene and analyzed changes in their ginsenoside profiles.
  
  
  RESULTS
  Overexpression of CYP716A53v2 led to increased accumulation of CYP716A53v2 mRNA in all transgenic roots compared to nontransgenic roots. Conversely, silencing of CYP716A53v2 mRNA in RNAi transgenic roots resulted in reduced CYP716A53v2 transcription. HPLC analysis revealed that transgenic roots overexpressing CYP716A53v2 contained higher levels of PPT-group ginsenosides (Rg1, Re, and Rf) but lower levels of PPD-group ginsenosides (Rb1, Rc, Rb2, and Rd). By contrast, RNAi transgenic roots contained lower levels of PPT-group compounds and higher levels of PPD-group compounds.
  
  
  CONCLUSIONS
  The production of PPD- and PPT-group ginsenosides can be altered by changing the expression of CYP716A53v2 in transgenic P. ginseng. The biological activities of PPD-group ginsenosides are known to differ from those of the PPT group. Thus, increasing or decreasing the levels of PPT-group ginsenosides in transgenic P. ginseng may yield new medicinal uses for transgenic P. ginseng.
authors: Department of Forest Resources, College of Forest and Environmental Sciences, Kangwon National University, Chunchon, Republic of Korea.
authors: Seong-Bum
authors: SB
authors: Park
authors: Department of Forest Resources, College of Forest and Environmental Sciences, Kangwon National University, Chunchon, Republic of Korea.
authors: Ju-Hyeon
authors: JH
authors: Chun
authors: Department of Forest Resources, College of Forest and Environmental Sciences, Kangwon National University, Chunchon, Republic of Korea.
authors: Yong-Wook
authors: YW
authors: Ban
authors: Department of Forest Resources, College of Forest and Environmental Sciences, Kangwon National University, Chunchon, Republic of Korea.
authors: Jung Yeon
authors: JY
authors: Han
authors: Department of Forest Resources, College of Forest and Environmental Sciences, Kangwon National University, Chunchon, Republic of Korea.
authors: Yong Eui
authors: YE
authors: Choi
keywords: genetic transformation; ginsenoside; protopanaxadiol 6-hydroxylase; saponins; triterpene