紫薇属香叶醇生物合成途径关键基因分离与功能分析

项目名称： 紫薇属香叶醇生物合成途径关键基因分离与功能分析

项目编号： No.31500574

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 农业科学

项目作者： 蔡明

作者单位： 北京林业大学

项目金额： 20万元

中文摘要： 培育香花紫薇品种一直是紫薇育种的重要目标。尾叶紫薇是香花种质资源，但由于缺少对其花香性状的深入研究，紫薇香花育种进展缓慢。课题组前期研究发现尾叶紫薇与紫薇主要挥发成分差异为香叶醇和其氧化产物橙花醛、柠檬醛。因此，香叶醇的合成与代谢可能是二者花香差异的关键环节。为探索紫薇属香叶醇生物合成途径，本研究以尾叶紫薇与紫薇品种‘白云映霞’为材料，一方面，研究花中香叶醇挥发量和时空挥发情况，比较花中香叶醇内源含量，分析紫薇对外源底物的催化效果；另一方面，克隆香叶醇合酶基因，进行生物信息学分析，开展原核表达与酶催化底物筛选，分析基因时空表达情况，筛选香叶醇生物合成关键基因，转化模式植物进行功能验证，通过酵母单杂交探索该基因的调控因子。最终揭示紫薇花香缺失的原因，明确紫薇属香叶醇生物合成的分子机理。研究结果将对阐明观赏植物香叶醇生物合成与调控机制有重要意义，为紫薇香花分子育种奠定基础。

中文关键词： 紫薇；花香；单萜；基因克隆；基因调控

英文摘要： Breeding fragrant cultivars is one of the most important goals of Lagerstroemia indica (crape myrtle) breeding. L. caudata is the fragrant germplasms in the genus of Lagerstroemia. The lack of depth study of its fragrant traits resulted in the slow progress of aroma crape myrtle breeding. Our previous study found that the main different flower volatiles between L. caudata and crape myrtles were geraniol, neral and citral. Neral and citral are the oxidation products of geraniol. Therefore, geraniol synthesis and metabolism may be the key part, which led to the difference of flower odor. To explore the biological pathways of geraniol synthesis in Lagerstroemia, L. caudata and ‘Baiyun Yingxia’ were used as materials. On metabolic level, geraniol volatilization and temporal volatile in flowers were analyzed using semi-quantitative methods. Endogenous quantity of geraniol was determined by GC-MS. The catalytic efficiency of flowers was analyzed by adding GPP and geraniol to crape myrtle as exogenous substrates. On gene level, genes related to geraniol synthase (GES) were isolated based on the known sequences. Analysis of gene structure and phylogeny, expression of GES in Escherichia coli, enzyme assays, alternative substrate analysis, real-time PCR were studied gradually to found the key GES genes. Then, Arabidopsis thaliana and Nicotiana benthamiana were used as model plant for functional verification. Yeast one-hybrid method was also used to detect transcription factors (TFs) of GES. The results will finally explain the reason of the lack of aroma and elucidate the molecular mechanism of geraniol biosynthesis in Lagerstroemia, which have an important effect on geraniol biosynthesis and regulatory mechanisms of ornamentals and lay the foundation for aroma molecular breeding in Lagerstroemia.

英文关键词： Lagerstroemia indica;volatile organic compounds;monoterpene;gene cloning;Gene regulation