Plantago sect. Coronopus contains our two focal species (P. coronopus L., P. crassifolia Forssk.), both with an overall conspicuous bi-hemispheric distribution range (Mediterranean and Middle Eastern regions in the Northern Hemisphere and South Africa in the Southern Hemisphere). We have evaluated up to 27 morphological characters from 96 herbarium specimens representing five out of seven species of that section that are currently recognised using principal coordinate analysis, linear discriminant analyses, agglomerative clustering, and classification tree analyses, in order to test the current taxonomic concepts of our two focal species. Furthermore, we used 54 individuals representing six out of those seven species of P. sect. Coronopus to construct molecular phylogenetic hypotheses by sequencing nuclear ribosomal DNA from the internal transcribed spacer region (ITS), the plastid trnL-F region, the plastid intergenic spacer region trnH-psbA and adopting maximum likelihood and Bayesian inference analyses. In the Northern Hemisphere, an Irano-Arabian clade initially identified as P. coronopus and shown as distinct in both morphological and phylogenetical terms fits a wider circumscription of P. crypsoides Boiss. due to lack of the prominent short and thick inflorescence scape following Boissier's description. The morphological differences between P. crassifolia from the Mediterranean region and P. crassifolia from South Africa (often named P. carnosa Lam.) were marginal, yet the molecular phylogenetic analyses of both nuclear and plastid markers clearly separated these evolutionary entities. Therefore, we re-instated the name P. carnosa as the correct name for South African P. crassifolia. Plantago carnosa differs from P. crassifolia by the combination of having stronger woody rootstocks, which are more often branched, by broader leaves (≥1.6 mm wide) and the fact that specimens more often turn brown when dried. Our dataset provides the best sampled phylogenetic hypothesis for P. sect. (and subg.) Coronopus to date, and reveals discordance between nuclear and plastid genealogies within P. sect. Maritima, which requires further investigation.Supporting Information may be found online in the Supporting Information section at the end of the article.
Herbarium specimens have become a major source of information in molecular biodiversity research, framing the term "herbarium genomics". However, obtaining good DNA from old herbarium specimens is still a challenge. Currently, DNA extraction methods from old herbarium material often yield highly degraded and fragmented DNA. A number of studies have discussed such methods, especially how to avoid further DNA fragmentation. This study aims to compare different DNA extraction methods applied to old herbarium material from Veronica subg. Pseudolysimachium. One such method is a CTABbased DNA extraction followed by a clean-up with paramagnetic beads that is used in the Jodrell Laboratory, Royal Botanic Gardens Kew, UK. This method was compared to a modified NucleoSpin Plant II protocol, based on silica columns, as used at the Technical University Munich-Freising, which was already successfully used for extracting DNA from a Linnean type specimen. Further tests were conducted on the influence of incubation time on the CTAB DNA extraction protocol with a subsample of specimens. Our preliminary results suggest that CTAB DNA extraction might have some advantages in specific cases but also that silica column-based methods have fewer problems with contamination by polysaccharides and polyphenolic compounds. Regarding the incubation time, we did not observe a clear pattern, but we developed several ideas on how to proceed with tests to find an optimal DNA extraction protocol to deal with highly fragmented DNA. Taking practical considerations into account, the column-based method proves to be preferable, especially when trying to reduce the amount of leaf tissue used, but further modifications of both methods should be explored.
Herbarium specimens have become a major source of information in molecular research of biodiversity. However, getting good DNA samples from old herbarium specimens is still a challenge. The purpose of this project is to test different DNA extraction methods for old material from herbaria that often exhibit high DNA fragmentation. We compared a CTAB-based DNA extraction that is followed by a clean-up with paramagnetic beads with a modified NucleoSpin Plant II protocol, based on silica columns. Our results demonstrate that silica column-based methods have less problems with contamination by polysaccharide and polyphenolic compounds. Taking practical considerations into account, the columnbased method is better especially when trying to reduce the amount of leaf tissue used since handling with a tiny pellet makes CTAB difficult.
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