Zhao Che, Xu Tianhui, Liang Yanlong, Zhao Shoujing, Ren Luquan, Wang Qian, Dou Bo
College of Biological and Agricultural Engineering, Jilin University, Changchun, 130022, China.
Plant Cell Rep. 2015 Aug;34(8):1307-15. doi: 10.1007/s00299-015-1788-7. Epub 2015 Apr 22.
Down-regulation of β-amyrin synthase gene expression by RNA interference led to reduced levels of β-amyrin and oleanane-type ginsenoside as well as up-regulation of dammarane-type ginsenoside level. In the biosynthetic pathway of ginsenosides, β-amyrin synthase catalyzes the reaction from oxidosqualene to β-amyrin, the proposed aglycone of oleanane-type saponins. Here, RNAi was employed to evaluate the role of this gene in ginsenoside biosynthesis of Panax ginseng hairy roots. The results showed that RNAi-mediated down-regulation of this gene led to reduced levels of β-amyrin and oleanane-type ginsenoside Ro as well as increased level of total ginsenosides, indicating an important role of this gene in biosynthesis of ginsenoside. Expression of key genes involved in dammarane-type ginsenoside including genes of dammarenediol synthase and protopanaxadiol and protopanaxatriol synthases were up-regulated in RNAi lines. While expression of squalene synthase genes was not significantly changed, β-amyrin oxidase gene was down-regulated. This work will be helpful for further understanding ginsenoside biosynthesis pathway.
RNA干扰导致β-香树脂醇合酶基因表达下调，进而使β-香树脂醇和齐墩果烷型人参皂苷水平降低，同时达玛烷型人参皂苷水平上调。在人参皂苷的生物合成途径中，β-香树脂醇合酶催化氧化鲨烯生成β-香树脂醇，β-香树脂醇是齐墩果烷型皂苷推测的苷元。在此，采用RNA干扰技术评估该基因在人参毛状根人参皂苷生物合成中的作用。结果表明，RNA干扰介导的该基因下调导致β-香树脂醇和齐墩果烷型人参皂苷Ro水平降低，同时总人参皂苷水平升高，表明该基因在人参皂苷生物合成中起重要作用。在RNA干扰株系中，参与达玛烷型人参皂苷生物合成的关键基因表达上调，包括达玛烯二醇合酶基因、原人参二醇和原人参三醇合酶基因。虽然鲨烯合酶基因表达没有显著变化，但β-香树脂醇氧化酶基因表达下调。这项工作将有助于进一步了解人参皂苷生物合成途径。
