Key Laboratory of Forest Genetics & Biotechnology of Ministry of Education, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
Key Laboratory of Forest Genetics & Biotechnology of Ministry of Education, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
Plant Physiol Biochem. 2021 Sep;166:700-711. doi: 10.1016/j.plaphy.2021.06.052. Epub 2021 Jun 29.
Terpenoids are important secondary metabolites in plants and are involved in stress responses and pollinator attraction. Geranylgeranyl pyrophosphate synthase (GGPPS) is a key synthase in the 2C-methyl-D-erythritol-4-phosphate (MEP) pathway of terpenoid synthesis, catalyzing the synthesis of diterpenoids. Liriodendron tulipifera is a nectar plant in North America. Little is known about the key genes involved in the biosynthetic pathways of terpenoids, the precursors of most compounds related to nectar, fragrance and coloring in flowers in L. tulipifera. In this study, the LtuGGPPS2 gene and its promoter (LtuGGPPS2-pro) were cloned from L. tulipifera. The results of sequence alignment showed that the LtuGGPPS2 gene is highly homologous to GGPPS genes of other plants. Subcellular localization analysis showed that the LtuGGPPS2 protein localizes to chloroplasts, suggesting that the LtuGGPPS2 gene is probably related to carotenoid and chlorophyll synthesis. Based on tissue expression profiles revealed by RT-qPCR, the expression level of the LtuGGPPS2 gene was highest in petals. These results were consistent with the changes in volatile and nonvolatile terpenoids in the flowers of L. tulipifera. GUS staining to examine the LtuGGPPS2 promoter indicated that it is responsive to hormones. Overexpression of the LtuGGPPS2 gene increased the carotenoid content and GGPPS enzyme activity in Arabidopsis thaliana, indicating that LtuGGPPS2 is the key terpenoid synthase in the flowers of L. tulipifera. Our findings lay a foundation for further functional analysis of the LtuGGPPS2 gene and deeper investigation of the terpenoid biosynthetic pathway in L. tulipifera.
萜类化合物是植物中重要的次生代谢物，参与应激反应和传粉者吸引。香叶基香叶基焦磷酸合酶（GGPPS）是萜类化合物合成 2C-甲基-D-赤藓醇-4-磷酸（MEP）途径中的关键合酶，催化二萜类化合物的合成。鹅掌楸是北美的蜜源植物。关于萜类化合物生物合成途径中的关键基因，即鹅掌楸花中与花蜜、香气和颜色有关的大多数化合物的前体，知之甚少。在这项研究中，从鹅掌楸中克隆了 LtuGGPPS2 基因及其启动子（LtuGGPPS2-pro）。序列比对结果表明，LtuGGPPS2 基因与其他植物的 GGPPS 基因高度同源。亚细胞定位分析表明，LtuGGPPS2 蛋白定位于叶绿体，表明 LtuGGPPS2 基因可能与类胡萝卜素和叶绿素合成有关。基于 RT-qPCR 揭示的组织表达谱，LtuGGPPS2 基因在花瓣中的表达水平最高。这些结果与鹅掌楸花中挥发性和非挥发性萜类化合物的变化一致。GUS 染色检查 LtuGGPPS2 启动子表明它对激素有反应。LtuGGPPS2 基因的过表达增加了拟南芥中的类胡萝卜素含量和 GGPPS 酶活性，表明 LtuGGPPS2 是鹅掌楸花中关键的萜类合酶。我们的研究结果为进一步研究 LtuGGPPS2 基因的功能以及鹅掌楸萜类生物合成途径奠定了基础。
