DNA isolation from century-old specimens of Fucus virsoides for the valorization of the historical collections of the Herbarium Patavinum

In recent years, herbaria and historical collections have become important tools for dissemination, historical and scientific research, resources with numerous applications in various fields such as teaching, open communication among scholars, taxonomic stability and studies in different disciplines (botanical, ecological, anatomical and morphological, evolutionary, paleobotanical research). Particularly important is the discipline of herbariomics that allows, through the process of DNA extraction from herbarium specimens, followed by high-throughput DNA sequencing and bioinformatics analysis, to conduct investigations about several topics such as pollution, habitat change, invasive species and climate change. However, DNA damage caused by time and conservation methods in old herbarium samples, in addition to external DNA contamination, makes nucleic acid extraction and amplification difficult. Here we present the results of DNA extraction (CTAB method) and amplification (PCR) conducted on six samples of the endemic Adriatic alga Fucus virsoides J.Agardh, 1868, collected between 1908 and 1932 and now conserved in the Padua Botanical Garden Herbarium. Furthermore, since the amplification failed, the study focused on the analysis of the putative problems that led to this result. Although DNA amplification failed, the adopted protocol has allowed the extraction of a more than adequate amounts of DNA with a concentration between 113.75 and 565.20 ng/µL. Our results highlight the possibility of applying this extraction method to these specimens, so that it will be feasible in the near future to sequence their DNA. A future study comparing the DNA of ancient and fresh samples may verify the presence of deleterious mutations accumulated during the demographic decline that the species has suffered along the northern Adriatic coast in recent years, possibly due to climate change.