Enhanced Triterpene Accumulation in Panax ginseng Hairy Roots Overexpressing Mevalonate-5-pyrophosphate Decarboxylase and Farnesyl Pyrophosphate Synthase

Abstract

To elucidate the function of mevalonate-5-pyrophosphate decarboxylase (MVD) and farnesyl pyrophosphate synthase (FPS) in triterpene biosynthesis, the genes governing the expression of these enzymes were transformed into Panax ginseng hairy roots. All the transgenic lines showed higher expression levels of <i>PgMVD</i> and <i>PgFPS</i> than that by the wild-type control. Among the hairy root lines transformed with <i>PgMVD</i>, M18 showed the highest level of transcription compared to the control (14.5-fold higher). Transcriptions of F11 and F20 transformed with <i>PgFPS</i> showed 11.1-fold higher level compared with control. In triterpene analysis, M25 of <i>PgMVD</i> produced 4.4-fold higher stigmasterol content (138.95 μg/100 mg, dry weight [DW]) than that by the control; F17 of <i>PgFPS</i> showed the highest total ginsenoside (36.42 mg/g DW) content, which was 2.4-fold higher compared with control. Our results indicate that metabolic engineering in P. ginseng was successfully achieved through Agrobacterium rhizogenes-mediated transformation and that the accumulation of phytosterols and ginsenosides was enhanced by introducing the <i>PgMVD</i> and <i>PgFPS</i> genes into the hairy roots of the plant. Our results suggest that <i>PgMVD</i> and <i>PgFPS</i> play an important role in the triterpene biosynthesis of P. ginseng