Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 310008, PR China; Graduate School of Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China; Key Laboratory of Tea Quality and Safety Control, Ministry of Agriculture and Rural Affairs, Hangzhou, 310008, PR China; College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, PR China.
Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 310008, PR China; Graduate School of Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China; Key Laboratory of Tea Quality and Safety Control, Ministry of Agriculture and Rural Affairs, Hangzhou, 310008, PR China.
J Plant Physiol. 2021 Mar-Apr;258-259:153358. doi: 10.1016/j.jplph.2020.153358. Epub 2021 Jan 5.
Silk tree, Albizia julibrissin Duraz, is an old ornamental plant and extensively cultivated in Asia. Previous works have discovered that the terpenoids were the dominating compounds in the floral VOC of A. julibrissin, however the biosynthesis of these terpenoids was poorly understood so far. Here, 11 terpene synthase genes (TPSs) were identified by transcriptome sequencing that fell into TPS-a, TPS-b and TPS-g subfamilies. The enzymatic activity tests showed that five genes were functional: AjTPS2 was a sesquiterpene synthase and produced α-farnesene and (Z, E)-β-farnesene; AjTPS5 was able to catalyze the formation of five monoterpenes and nine sesquiterpenes; AjTPS7, AjTPS9 and AjTPS10 were dedicated monoterpene synthases, as AjTPS7 and AjTPS10 formed the single product β-ocimene and linalool, respectively, and AjTPS9 produced γ-terpinene with other three monoterpenes. More importantly, the main catalytic products of the characterized AjTPSs were consistent with the terpenoids observed in A. julibrissin volatiles. Combining terpene chemistry, TPSs biochemical activities and gene expression analysis, we demonstrate that AjTPS2, AjTPS5, AjTPS7, AjTPS9 and AjTPS10 are responsible for the volatile terpenoids biosynthesis in A. julibrissin.
丝棉木，合欢树 Albizia julibrissin Duraz，是一种古老的观赏植物，在亚洲广泛种植。先前的研究发现萜类化合物是合欢花挥发性有机化合物（VOC）中的主要化合物，但到目前为止，这些萜类化合物的生物合成还知之甚少。本研究通过转录组测序鉴定了 11 个萜烯合酶基因（TPSs），它们分为 TPS-a、TPS-b 和 TPS-g 亚家族。酶活性测试表明，有 5 个基因具有功能：AjTPS2 是一种倍半萜合酶，可产生α-法呢烯和（Z，E）-β-法呢烯；AjTPS5 能够催化形成 5 种单萜和 9 种倍半萜；AjTPS7、AjTPS9 和 AjTPS10 是专一的单萜合酶，AjTPS7 和 AjTPS10 分别形成单产物β-罗勒烯和芳樟醇，AjTPS9 与其他三种单萜一起产生γ-松油烯。更重要的是，表征的 AjTPSs 的主要催化产物与合欢花挥发物中的萜类化合物一致。结合萜类化学、TPSs 生化活性和基因表达分析，我们证明了 AjTPS2、AjTPS5、AjTPS7、AjTPS9 和 AjTPS10 负责合欢花挥发性萜类化合物的生物合成。
