Supplementary information files for Fourier transform infrared spectroscopy as a non-destructive method for analysing herbarium specimens

Supplementary files for article Fourier transform infrared spectroscopy as a non-destructive method for analysing herbarium specimensDried plant specimens stored in herbaria are an untapped treasure chest of information on environmental conditions, plant evolution and change over many hundreds of years. Owing to their delicate nature and irreplaceability, there is limited access for analysis to these sensitive samples, particularly where chemical data are obtained using destructive techniques. Fourier transform infrared (FTIR) spectroscopy is a chemical analysis technique which can be applied non-destructively to understand chemical bonding information and, therefore, functional groups within the sample. This provides the potential for understanding geographical, spatial and species-specific variation in plant biochemistry. Here, we demonstrate the use of mid-FTIR microspectroscopy for the chemical analysis of Drosera rotundifolia herbarium specimens, which were collected 100 years apart from different locations. Principal component and hierarchical clustering analysis enabled differentiation between three main regions on the plant (lamina, tentacle stalk and tentacle head), and between the different specimens. Lipids and protein spectral regions were particularly sensitive differentiators of plant tissues. Differences between the different sets of specimens were smaller. This study demonstrates that relevant information can be extracted from herbarium specimens using FTIR, with little impact on the specimens. FTIR, therefore, has the potential to be a powerful tool to unlock historic information within herbaria.

补充文件，文章标题为《傅里叶变换红外光谱作为分析植物标本的无损检测方法》。保存在标本馆中的干燥植物标本是关于环境条件、植物演化和数百年来变化的无尽宝藏。鉴于其脆弱性和不可替代性，对这些敏感样本的分析访问有限，特别是在使用破坏性技术获取化学数据的情况下。傅里叶变换红外光谱（FTIR）是一种化学分析技术，可无损应用于理解化学键合信息，从而识别样本中的官能团。这为理解植物生物化学在地理、空间和物种特异性方面的变异提供了可能性。在此，我们展示了使用中红外微光谱法对捕蝇草（Drosera rotundifolia）标本馆标本进行化学分析的应用，这些标本分别来自相隔100年的不同地点。主成分分析和层次聚类分析使得对植物三个主要区域（叶片、触手柄和触手头）以及不同标本之间的区分成为可能。脂质和蛋白质光谱区域是特别敏感的组织区分器。不同标本集之间的差异较小。这项研究表明，使用FTIR可以从植物标本中提取相关信息，而对标本的影响微乎其微。因此，FTIR具有成为解锁标本馆中历史信息的强大工具的潜力。