Terpenoids are one of the main components of plant aromas. In the present study we investigated these compounds in Osmanthus fragrans Lour., which is a fragrant plant widely used for the production of essential oils. Quantitative real-time PCR (qRT-PCR) results of enzymes associated with the 2-C-methylerythritol-4-phosphate pathway confirmed that the TPS is a key enzyme for terpenoid synthesis in O. fragrans. In a series of experiments, we identified the TPS candidate genes in O. fragrans and revealed the underlying catalytic activity and subcellular localisation of the encoded proteins. Because there is no available O. fragrans reference genome, we sequenced and analysed its transcriptome and identified two putative TPS genes, OfTPS1 and OfTPS2. According to qRT-PCR analysis, both genes were most highly expressed at the full-bloom stage, suggesting that OfTPS1 and OfTPS2 contribute to O. fragrans terpenoid synthesis. To verify this hypothesis, we constructed prokaryotic expression vectors to obtain protein. In order to study the function of OfTPS1 and OfTPS2 in the synthesis of monoterpenes, the obtained proteins were reacted with geranyl pyrophosphate. As a result, two kinds of monoterpenes, (E)-β-ocimene and linalool, were detected from reaction products, respectively. In conclusion, OfTPS1 and OfTPS2 are both monoterpene synthases.

中文翻译：

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结合转录组测序和原核表达研究桂花2-C-甲基赤藓糖醇-4-磷酸途径中的关键酶

萜类化合物是植物香气的主要成分之一。在本研究中，我们研究了桂花中的这些化合物，桂花是一种广泛用于生产精油的芳香植物。与 2-C-methylerythritol-4-phosphate 途径相关的酶的定量实时 PCR (qRT-PCR) 结果证实，TPS 是 O. fragrans 中萜类化合物合成的关键酶。在一系列实验中，我们鉴定了 O. fragrans 中的 TPS 候选基因，并揭示了编码蛋白质的潜在催化活性和亚细胞定位。因为没有可用的 O. fragrans 参考基因组，我们对其转录组进行了测序和分析，并确定了两个推定的 TPS 基因，OfTPS1 和 OfTPS2。根据 qRT-PCR 分析，两个基因在盛花期表达最高，表明 OfTPS1 和 OfTPS2 有助于 O. fragrans 萜类化合物的合成。为了验证这一假设，我们构建了原核表达载体以获得蛋白质。为了研究OfTPS1和OfTPS2在单萜合成中的作用，将所得蛋白质与焦磷酸香叶基反应。结果，从反应产物中分别检测到两种单萜，(E)-β-罗勒烯和芳樟醇。总之，OfTPS1和OfTPS2都是单萜合酶。(E)-β-罗勒烯和芳樟醇，分别从反应产物中检测到。总之，OfTPS1和OfTPS2都是单萜合酶。(E)-β-罗勒烯和芳樟醇，分别从反应产物中检测到。总之，OfTPS1和OfTPS2都是单萜合酶。