Can biochemical phenotype, obtained from herbarium samples, help taxonomic decisions? - A case study using Gentianaceae

With the emergence of metabolomics, small quantities of plant material can be used to generate chemical fingerprints with high throughput for comparative analyses without the need for tedious and in-depth classical phytochemical investigation of large amounts of plant material. Here, we tested the hypothesis that herbarium samples themselves could be used as suitable material for untargeted metabolomic analysis and taxon discrimination based on biochemical phenotypes. We employed mass-spectrometry-based metabolite profiling to classify given species of chemotaxonomical relevance from the Gentianaceae family based on their biochemical phenotypic differences. Our dataset consisted of 605 accessions each with 910 mass spectral features, representing 59 species from 23 genera that extend over 6 tribes of the family. We found that minute amounts of herbarium specimens (less than 50 mg) were sufficient to obtain comprehensive fingerprints for all investigated individuals. Morphologically or genetically distinct species were differentiated using metabolite profiles, confirming taxon distinctions and validating the utility of this method for identification and differentiation. Overall, our results suggest that metabolite profiling of herbarium specimens may be suitable for taxonomic studies and also opens new ground for detailed investigations of their specialised metabolite contents.