Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany.
Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
Sci Rep. 2016 Oct 31;6:36074. doi: 10.1038/srep36074.
High-resolution atmospheric-pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI) at 10 μm pixel size was performed to unravel the spatio-chemical distribution of major secondary metabolites in the root of Paeonia lactiflora. The spatial distributions of two major classes of bioactive components, gallotannins and monoterpene glucosides, were investigated and visualized at the cellular level in tissue sections of P. lactiflora roots. Accordingly, other primary and secondary metabolites were imaged, including amino acids, carbohydrates, lipids and monoterpenes, indicating the capability of untargeted localization of metabolites by using high-resolution MSI platform. The employed AP-SMALDI MSI system provides significant technological advancement in the visualization of individual molecular species at the cellular level. In contrast to previous histochemical studies of tannins using unspecific staining reagents, individual gallotannin species were accurately localized and unequivocally discriminated from other phenolic components in the root tissues. High-quality ion images were obtained, providing significant clues for understanding the biosynthetic pathway of gallotannins and monoterpene glucosides and possibly helping to decipher the role of tannins in xylem cells differentiation and in the defence mechanisms of plants, as well as to investigate the interrelationship between tannins and lignins.
采用 10μm 像素大小的高分辨率常压扫描微探针基质辅助激光解吸/电离质谱成像（AP-SMALDI MSI）技术，揭示了芍药根中主要次生代谢物的空间化学分布。在芍药根组织切片中，研究并可视化了两类主要生物活性成分——鞣花单宁和单萜糖苷——在细胞水平上的空间分布。此外，还对包括氨基酸、碳水化合物、脂质和单萜在内的其他初级和次级代谢物进行了成像，表明该高分辨率 MSI 平台具有对代谢物进行非靶向定位的能力。所采用的 AP-SMALDI MSI 系统在细胞水平上对单个分子物种的可视化提供了重要的技术进步。与使用非特异性染色试剂的单宁的先前组织化学研究相比，单个鞣花单宁种类被准确定位，并与根组织中的其他酚类成分明确区分开来。获得了高质量的离子图像，为理解鞣花单宁和单萜糖苷的生物合成途径提供了重要线索，并可能有助于解析单宁在木质部细胞分化和植物防御机制中的作用，以及研究单宁和木质素之间的相互关系。
