Wan Lingyun, Huang Qiulan, Li Cui, Yu Haixia, Tan Guiyu, Wei Shugen, El-Sappah Ahmed H, Sooranna Suren, Zhang Kun, Pan Limei, Zhang Zhanjiang, Lei Ming
Guangxi Key Laboratory for High-Quality Formation and Utilization of Dao-Di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China.
National Center for Traditional Chinese Medicine (TCM) Inheritance and Innovation, Guangxi Botanical Garden of Medicinal Plants, Nanning, China.
Front Plant Sci. 2024 Jan 12;14:1295186. doi: 10.3389/fpls.2023.1295186. eCollection 2023.
(L.) Urban is a well-known medicinal plant which has multiple pharmacological properties. Notably, the leaves of contain large amounts of triterpenoid saponins. However, there have only been a few studies systematically elucidating the metabolic dynamics and transcriptional differences regarding triterpenoid saponin biosynthesis during the leaf development stages of Here, we performed a comprehensive analysis of the metabolome and transcriptome to reveal the dynamic patterns of triterpenoid saponin accumulation and identified the key candidate genes associated with their biosynthesis in leaves. In this study, we found that the key precursors in the synthesis of terpenoids, including DMAPP, IPP and β-amyrin, as well as 22 triterpenes and eight triterpenoid saponins were considered as differentially accumulated metabolites. The concentrations of DMAPP, IPP and β-amyrin showed significant increases during the entire stage of leaf development. The levels of 12 triterpenes decreased only during the later stages of leaf development, but five triterpenoid saponins rapidly accumulated at the early stages, and later decreased to a constant level. Furthermore, 48 genes involved in the MVA, MEP and 2, 3-oxidosqualene biosynthetic pathways were selected following gene annotation. Then, 17 CYP450s and 26 UGTs, which are respectively responsible for backbone modifications, were used for phylogenetic-tree construction and time-specific expression analysis. From these data, by integrating metabolomics and transcriptomics analyses, we identified and as the candidate genes associated with DMAPP and IPP synthesis, respectively, and as the one regulating β-amyrin synthesis. Two genes from the CYP716 family were confirmed as and . We also selected two UGT73 families as candidate genes, associated with glycosylation of the terpenoid backbone at C-3 in . These findings will pave the way for further research on the molecular mechanisms associated with triterpenoid saponin biosynthesis in .
（L.）Urban是一种著名的药用植物，具有多种药理特性。值得注意的是，其叶子含有大量三萜皂苷。然而，关于Urban叶子发育阶段三萜皂苷生物合成的代谢动力学和转录差异，仅有少数研究进行了系统阐明。在此，我们对代谢组和转录组进行了全面分析，以揭示三萜皂苷积累的动态模式，并鉴定了与其叶子生物合成相关的关键候选基因。在本研究中，我们发现萜类化合物合成的关键前体，包括二甲基烯丙基焦磷酸（DMAPP）、异戊烯基焦磷酸（IPP）和β-香树脂醇，以及22种三萜和8种三萜皂苷被视为差异积累代谢物。DMAPP、IPP和β-香树脂醇的浓度在叶子发育的整个阶段均显著增加。12种三萜的含量仅在叶子发育后期下降，但5种三萜皂苷在早期迅速积累，随后降至恒定水平。此外，在基因注释后，选择了48个参与甲羟戊酸（MVA）、2-C-甲基-D-赤藓糖醇-4-磷酸（MEP）和2,3-氧化角鲨烯生物合成途径的基因。然后，分别负责骨架修饰的17个细胞色素P450（CYP450）和26个尿苷二磷酸葡萄糖基转移酶（UGT）用于构建系统发育树和时间特异性表达分析。基于这些数据，通过整合代谢组学和转录组学分析，我们分别鉴定出与DMAPP和IPP合成相关的候选基因 和 ，以及调控β-香树脂醇合成的基因 。来自CYP716家族的两个基因被确认为 和 。我们还选择了两个UGT73家族作为候选基因，与Urban中萜类骨架C-3位的糖基化相关。这些发现将为进一步研究Urban中三萜皂苷生物合成的分子机制铺平道路。
