咖啡碱是茶叶中的重要特征成分、品质成分和功能成分，一直为茶树育种改良的重要目标。TCS1是茶树咖啡碱合成途径中的关键基因，前期研究发现其在少量特异资源中存在着数种酶活性或表达水平显著不同的等位变异，但目前TCS1等位基因尚未得到充分挖掘,TCS1的表达调控和遗传机制也不明确，这些限制了特异资源的有效利用。本项目拟在丰富的茶树资源中分离更多的特异TCS1等位基因，利用体外融合表达明确其编码蛋白功能。通过构建不同TCS1等位基因启动子的含GUS基因的表达载体，转基因拟南芥研究启动子活性差异。利用2个由父母本均含有特异TCS1等位基因的资源构建的F1分离群体研究TCS1的遗传效应，明确决定特异种质咖啡碱性状的基因型。本研究将深入解析TCS1等位变异在茶树咖啡碱合成代谢中的作用机制，对特异咖啡碱育种具有重要的科学意义和应用价值。

Caffeine is an important characteristic component and makes important contribution to the quality and function of tea, which has been the important goal of tea breeding. TCS1 is a key gene involved in caffeine biosynthesis pathways of tea plant. In previous studies, alleles with different catalysis function or expression levels have been found in few special germplasms. While more rare alleles have not been isolated in other germplasms, the transcription regulation and genetic mechanism of TCS1 is not clear yet, these limit the effective utilization of specific tea germplasms. In this study, we will mine special TCS1 alleles in more tea germplasms. Special TCS1 alleles will be introduced into the E. coli cells and induced to express the functional proteins. To analyze the transcriptional mechanism of TCS1, different promoters will be fused to the GUS reporter gene in a plant expression vector and transferred into Arabidopsis thaliana. In addition, TCS1 genetic effects and the genotype of special germplasms with extraordinary caffeine content will be evaluated by using two F1 segregating populations which created by parents with special alleles. This study will help us understand the function and genetic mechanism of TCS1 allelic variations involved in caffeine biosynthesis of tea plant more deeply, which has important scientific significance and application value for tea breeding.