School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, 510006, China; State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700, China.
State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700, China; School of Pharmacy, Henan University of Chinese Medicine, Zhengzhou, 450008, China.
Plant Sci. 2022 Apr;317:111203. doi: 10.1016/j.plantsci.2022.111203. Epub 2022 Feb 1.
Cinnamomum burmannii is a traditional plant that has long been used as a spice, food preservative, and food flavoring. Essential oils in C. burmannii, which mainly consist of mono- and sesquiterpenes such borneol, linalool, and caryophyllene, have impressive pharmaceutical properties. Although the transcriptome-based discovery of (+)-bornyl diphosphate synthase (CbTPS1) from C. burmannii was reported in our previous study, the remaining terpene synthases (TPSs) corresponding to various terpene biosynthesis pathways remain unidentified. In this study, we report the results of RNA-sequencing of a borneol type plant and functional characterization of six additional full-length candidate TPS genes (named CbTPS2-7). Phylogenetic analysis revealed that CbTPS2 and CbTPS3 together with the previously identified CbTPS1 protein belong to the TPS-b subfamily, and enzyme assays using geranyl diphosphate (GPP) and farnesyl diphosphate (FPP) as substrates revealed that CbTPS1, CbTPS2 and CbTPS3 catalyze the formation of monoterpenes. CbTPS4, CbTPS5, and CbTPS6, which belong to the TPS-a clade, generated monoterpenes and sesquiterpenes. CbTPS7, which belongs to the TPS-g clade, showed linalool/nerolidol synthase activity. These CbTPSs identified in C. burmannii produced a total of 10 monoterpenes and 14 sesquiterpenes in an in vitro assay. These findings clarify the biosynthesis pathways of 13 monoterpenoids and 12 sesquiterpenoids in the leaf essential oil of C. burmannii and shed light on terpene biosynthesis in Cinnamomum.
肉桂是一种传统植物，长期以来一直被用作香料、食品防腐剂和食品调味剂。肉桂中的精油主要由单萜和倍半萜组成，如龙脑、芳樟醇和石竹烯，具有令人印象深刻的药用特性。尽管我们之前的研究报告了肉桂中（+）- 龙脑基二磷酸合酶（CbTPS1）的基于转录组的发现，但对应于各种萜类生物合成途径的剩余萜烯合酶（TPS）仍然未被识别。在这项研究中，我们报告了龙脑型植物的 RNA 测序结果，并对另外六个全长候选 TPS 基因（命名为 CbTPS2-7）进行了功能表征。系统发育分析表明，CbTPS2 和 CbTPS3 与之前鉴定的 CbTPS1 蛋白一起属于 TPS-b 亚家族，使用香叶基二磷酸（GPP）和法呢基二磷酸（FPP）作为底物的酶测定表明 CbTPS1、CbTPS2 和 CbTPS3 催化单萜的形成。属于 TPS-a 分支的 CbTPS4、CbTPS5 和 CbTPS6 生成单萜和倍半萜。属于 TPS-g 分支的 CbTPS7 表现出芳樟醇/橙花叔醇合酶活性。在体外试验中，这些在肉桂中鉴定的 CbTPSs 总共产生了 10 种单萜和 14 种倍半萜。这些发现阐明了肉桂叶精油中 13 种单萜和 12 种倍半萜的生物合成途径，并揭示了肉桂属植物中萜类化合物的生物合成。
