黄花蒿开花诱导与青蒿素合成关键酶基因的关系研究

Study on the Relationship between the Flowering Induction in vitro and Genes Encoding the Key Enzyme of Artemisinin Biosynthesis in Artemisia annua L.

青篙素是重要的抗疟药物,青篙素合成量在黄花篙的成花期显著提高。本研究以试管开花为研究体系,探讨黄花篙开花的诱导因子与青篙素生物合成的关系。结果表明:外源细胞分裂素是黄花篙试管开花形成的必需因子,2 mg/L玉米素(ZT)对茎段外植体分化花芽效果最好。在ZT作用下赤霉素(GA3)较显著地提高了黄花篙花芽的分化率。在诱导培养基中只加1/2 NH_4NO_3或不加NH_4NO_3,也有利于花芽的分化和发育。花期植株脱氧木酮糖磷酸合酶(DXS)、脱氧木酮糖磷酸还原酶(DXR)、3-轻基-3-甲基戊二单酞辅酶A还原酶(HMGR)、法呢基焦磷酸合成酶(FPP)基因表达水平显著高于营养期植株,具有成花诱导活性的外源激素组合如ZT、GA3和叫哚丁酸(IBA)可促进植株中青篙素生物合成下游途径中紫穗槐二烯合酶(ADS)和细胞色素P450单氧酶(CYP)基因表达提高青篙素的合成量。本研究为探讨成花物质对青篙素生物合成的影响和利用花器官诱导青篙素高产植株提供了基础和方法。

Artemisinin is an effective antimalarial drug.Its content is increased significantly during flowering period of Artemisia annua L.In this study we used in vitro flowering plantlets to explore the relationship between the flowering induction and biosynthesis of artemisin.Our results demonstrated that cytokinin is a decisive factor for flowering in vitro.Among the used regulators zeatin（ZT） at 2 mg/L was the best one for the differentiation of vegetative explants to flower buds.With the combination of gibberellin GA3,the differentiation was promoted markedly.The frequencies of flowering induction was enhanced in the modified MS medium with 1/2 NH_4NO_3 content or without NH_4NO_3.During the flowering period the expression of HMG-CoA reductase（HMGR）,1- deoxy-D-xylulose- 5- phosphate synthase（DXS）,1-deoxy-D-xylulose-5-phosphate reductoisomerase（DXR） and farnesyl diphosphate synthase（FPS） genes in earlier step of artemisinin biosynthetic pathway were enhanced significantly when compared to that of control during vegetative period.The phytohormones of flowering induction activity including ZT,GA3 and 3-indolebutyric acid（IBA） could stimulte the expression levels of amorpha-4,11-diene synthase（ADS） and amorpha-4,11-diene monooxygenase（CYP） genes in the end of artemisinin biosynthetic pathway,then improved the artemisnin content in flowering plants.Our results are helpful for exploring the effects of flowering inductive regulators on artemisinin biosynthesis and provided a potential strategy for obtaining A.annua plants with higher yields of artemisinin from flower organs.