State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.
School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, China.
Plant Cell Environ. 2018 Nov;41(11):2693-2703. doi: 10.1111/pce.13395. Epub 2018 Aug 7.
Ginkgo biloba is one of the oldest extant seed plants and has a number of unique properties and uses. Numerous efforts have characterized metabolites within the ginkgo plant and their corresponding biosynthesis pathways, but spatio-chemical information on ginkgo metabolites is lacking. Mass spectrometry (MS) imaging was used to interrogate the spatio-chemical localization of metabolites with matrix-assisted laser desorption/ionization and laser desorption/ionization Fourier-transform ion cyclotron resonance MS across the ginkgo leaf. Flavonoids, particularly unexpected and rare flavonoid cyclodimers, were detected predominately from leaf epidermis; ginkgolic acids and cardanols were observed exclusively in the secretory cavities. A non-uniform distribution of flavonoids observed between the upper and lower leaf epidermis was verified by liquid chromatography-MS analyses. Other metabolites, such as saccharides, phospholipids, and chlorophylls, occurred mainly in mesophyll cells. Furthermore, organ- and tissue-specific distributions of ginkgolides were revealed in the ginkgo root, young stem, and leaf. The acquired ion images provide important information regarding biosynthesis, transportation, and accumulation of metabolites throughout the ginkgo plant and should help us to understand the physiological roles of several plant secondary metabolites.
银杏是现存最古老的种子植物之一，具有许多独特的特性和用途。人们已经对银杏植物中的代谢物及其相应的生物合成途径进行了大量的研究，但银杏代谢物的时空化学信息却很缺乏。本研究采用基质辅助激光解吸/电离和激光解吸/电离傅里叶变换离子回旋共振质谱法，对银杏叶进行了质谱成像分析，以研究代谢物的时空化学定位。黄酮类化合物，特别是意想不到的罕见黄酮类环二聚体，主要从叶片表皮中检测到；银杏酸和银杏醇则仅在分泌腔中观察到。通过液相色谱-质谱分析验证了在上、下表皮之间观察到的黄酮类化合物的非均匀分布。其他代谢物，如糖、磷脂和叶绿素，主要存在于叶肉细胞中。此外，还揭示了银杏内酯在银杏根、嫩茎和叶中的器官和组织特异性分布。获得的离子图像为银杏植物中代谢物的生物合成、运输和积累提供了重要信息，应该有助于我们理解几种植物次生代谢物的生理作用。
