DXS和LIS基因在薰衣草萜类花香成分生物合成中的功能研究

Lavandula is an important crop for distinctive economy，as known as“Queen of fragrance”，the essential oils of lavandula have health and economic value. The main floral components identified were linalool (terpenoids) and linalyl acetate (acetic ester compounds), but it is not clear the analysis functions and molecular mechanisms of metabolic regulation in lavandula at present. In precious study, comparative analysis of oil components was conducted by Gas Chromatography-Mass Spectrometer(GC-MS), “701” variety with high oil content could be considered good materials for extracting lavandula oil and breeding new cultivars. In this study, two genes encoding 1-deoxy-n-xylulose-5-phosphate synthase (DXS) and linalool synthase (LIS) involved in the terpene biosynthesis pathways were isolated from “701”. Based on these, the expression patterns of these genes in different flower development stages and different parts of floral organs will have determined by real-time quantitative fluorescence PCR, differential expression analysis of gene in different strains, subcellular localization of DXS and LIS gene and detection of enzyme activity. A comprehensive analysis was carried out into the relationship between expression of two terpene synthesis genes and accumulation of main volatile terpenes and their acetic acid ester derivatives, and , enzyme activity of floral biosynthesis. Cloning DXS and LIS gene and identify its function by transforming the model plant and lavandula. Analysis functions and molecular mechanisms of DXS and LIS genes in biosynthesis, and provide a clear function candidate genetic resources for lavandula production and quality improvement.

薰衣草是新疆重要的特色经济作物，素有“芳香女王”的美誉，其花穗中提取的精油具有很高的保健和经济价值。芳樟醇（萜类化合物）及乙酸芳樟酯（芳樟醇的酯类化合物）是薰衣草精油的主要芳香成分，但它们在薰衣草中代谢调控的分子机制目前尚不清楚。通过前期对新疆薰衣草种质资源精油产量及品质的评价结果，选定高油品种“701”为供体，克隆了薰衣草萜类花香成分生物合成关键酶基因DXS和LIS基因。在此基础上，本研究拟对DXS和LIS基因在薰衣草花器官中的时空表达模式及不同薰衣草品系中的表达量差异进行分析，结合基因的亚细胞定位及目的蛋白酶的活性检测，初步探讨它们与薰衣草萜类花香成分生物合成的调控关系；进一步转化模式植物和薰衣草，比较转基因植株和对照植株的花香、芳樟醇和乙酸芳樟酯含量等性状的变化情况，探明DXS、LIS基因在薰衣草萜类花香成分生物合成中的功能，为培育精油高产、优质的薰衣草新品系提供候选基因。

萜类花香物质是薰衣草精油的主要成分，获取调控萜类花香物质合成的关键基因可为改良薰衣草精油性状提供优异基因资源。本项目研究结果表明:（1）DXS、LIS1、LIS2基因在薰衣草高油品系和低油品系花器官中的表达模式存在差异, 基因表达规律与薰衣草花器官萜类物质含量变化情况具有一定的相关性；DXS、LIS1蛋白均位于叶绿体中，LIS1、LIS2蛋白具有单萜合酶活性；（2）转DXS、LIS1、LIS2基因拟南芥、薰衣草株中萜类物质含量增加，基因沉默植株的萜类物质含量下降；（3）验证了DXS、LIS1、LIS2基因具有调控薰衣草萜类物质合成的功能，同时已获得的转基因薰衣草株系可作为新品种选育的候选品系。