Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, 301617, Tianjin, China.
National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, 100700, Beijing, China.
BMC Plant Biol. 2022 Mar 22;22(1):132. doi: 10.1186/s12870-022-03537-5.
Syringa pinnatifolia Hemsl. is a shrub belonging to the Oleaceae family. The peeled woody stems and roots of S. pinnatifolia are used in Chinese traditional medicine. This plant has been used for centuries, and modern pharmacological research has revealed its medicinal value. However, the wild populations of S. pinnatifolia have been decreasing, and it has been listed as an endangered plant in China. To elucidate the molecular mechanism leading to the synthesis of the major components of S. pinnatifolia for its further development and sustainable use, this study compared peeled stems and twigs at the metabolic and molecular levels.
Peeled stems with the purple substance visible (SSP) and peeled twigs without the purple substance (TSP) were compared at different levels. Microscopic observation showed resin-like fillers in SSP and wood fiber cell walls approximately 1.0 μm thicker than those in TSP (wood fiber cell thickness approximately 2.7 μm). In addition, 104 volatile organic compounds and 870 non-volatile metabolites were detected in the non-targeted and widely-targeted metabolome analyses, respectively. Among the 76 differentially accumulated metabolites (DAMs) detected, 62 were up-accumulated in SSP. Most of these DAMs were terpenes, of which 90% were identified as sesquiterpenes in the volatile organic compound analysis. In the analysis of the non-volatile metabolites, 21 differentially accumulated lignans were identified, of which 18, including five subtypes, were accumulated in SSP. RNA sequencing revealed 4,421 upregulated differentially expressed genes (DEGs) and 5,522 downregulated DEGs in SSP compared with TSP, as well as 33,452 genes that were not differentially expressed. Analysis of the DEGs suggested that sesquiterpenes and lignans were mostly biosynthesized via the mevalonate and phenylpropanoid pathways, respectively. Additionally, in SSP, the enriched Gene Ontology terms included response to biotic stimulus and defense response, while the enriched Kyoto Encyclopedia of Genes and Genomes pathways included plant-pathogen interaction and many other pathways related to plant immunity.
This study provides metabolome and transcriptome information for S. pinnatifolia, suggesting that biotic stimuli, including pathogens, are potential and valuable approaches to promoting the biosynthesis of the metabolites linked to the medicinal properties of this plant.
丁香叶悬钩子是木樨科悬钩子属的灌木。丁香叶悬钩子的去皮木茎和根在中国传统医学中被使用。这种植物已经使用了几个世纪，现代药理学研究揭示了它的药用价值。然而，丁香叶悬钩子的野生种群正在减少，它已被列为中国濒危植物。为了阐明导致丁香叶悬钩子主要成分合成的分子机制，以进一步开发和可持续利用该植物，本研究在代谢和分子水平上比较了去皮的茎和嫩枝。
比较了具有可见紫色物质的去皮茎（SSP）和无紫色物质的去皮嫩枝（TSP）。显微镜观察显示 SSP 中有树脂状填充物，而 TSP 中的木质纤维细胞壁厚度约为 1.0 μm（木质纤维细胞厚度约为 2.7 μm）。此外，非靶向和广泛靶向代谢组学分析分别检测到 104 种挥发性有机化合物和 870 种非挥发性代谢物。在检测到的 76 种差异积累代谢物（DAMs）中，有 62 种在 SSP 中呈上调积累。这些 DAM 大多是萜类化合物，其中 90%在挥发性有机化合物分析中被鉴定为倍半萜。在非挥发性代谢物分析中，鉴定出 21 种差异积累木质素，其中 18 种，包括 5 种亚型，在 SSP 中积累。与 TSP 相比，SSP 中转录组测序显示 4421 个上调的差异表达基因（DEGs）和 5522 个下调的 DEGs，以及 33452 个未差异表达的基因。DEGs 分析表明，倍半萜和木质素主要通过甲羟戊酸和苯丙氨酸途径合成。此外，在 SSP 中，富集的基因本体术语包括对生物刺激的反应和防御反应，而富集的京都基因与基因组百科全书途径包括植物-病原体相互作用和许多其他与植物免疫相关的途径。
本研究为丁香叶悬钩子提供了代谢组和转录组信息，表明生物刺激物，包括病原体，可能是促进与该植物药用特性相关代谢物生物合成的有价值的方法。
