Upregulation of ginsenoside and gene expression related to triterpene biosynthesis in ginseng hairy root cultures elicited by methyl jasmonate
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In this study, methyl jasmonate (MJ)-induced changes of triterpene saponins in ginseng (Panax ginseng C.A. Meyer) hairy roots and expression profiling of relevant responsive genes were analyzed. The transcription of PgSS (squalene synthase), PgSE (squalene epoxidase), and PNA (dammarenediol synthase-II) genes in hairy root cultures elicited by MJ treatment increased as compared with the controls, whereas that of PNX (cycloartenol synthase) decreased slightly. In order to select candidate genes encoding for cytochrome P450-dependent hydroxylase or glucosyltransferase associated with triterpene biosynthesis, RT-PCR analysis was conducted following MJ elicitation. No differences were observed in any expression among the five genes associated with the cytochrome P450 family, when compared to that of control. For candidates of the glucosyltransferase gene,expression of EST IDs PG07020C06, PG07025D04, and PG07029G02 was upregulated. In an effort to assess the effects of MJ elicitation on the biosynthesis of triterpene saponin, protopanaxadiol saponin (Rb group) and protopanaxatriol saponin (Rg group) contents in hairy roots were evaluated by HPLC analysis. With 7 days of MJ elicitation, levels of all ginseonsides of the two-groups increased much higher than that observed in the control. In particular, protopanaxadiol-type saponin contents increased by 5.5–9.7 times that of the control, whereas protopanaxatriol-type saponin contents were increased by 1.85–3.82-fold. In the case of Rg1 ginsenoside after MJ elicitation, the content was affected negatively in ginseng hairy root cultures.
KeywordsCytochrome P450-depentent hydroxylase Glucosyltransferase Methyl jasmonate Protopanaxadiol Protopanaxatriol
Farnesyl diphosphate synthase