Ancient DNA from historical and subfossil wood has a great potential to provide new insights into the history of tree populations. However, its extraction and analysis have not become routine, mainly because contamination of the wood with modern plant material can complicate the verification of genetic information. Here, we used sapwood tissue from 22 subfossil pines that were growing c. 13 000 yr bp in Zurich, Switzerland. We developed and evaluated protocols to eliminate surface contamination, and we tested ancient DNA authenticity based on plastid DNA metabarcoding and the assessment of post-mortem DNA damage. A novel approach using laser irradiation coupled with bleaching and surface removal was most efficient in eliminating contaminating DNA. DNA metabarcoding confirmed which ancient DNA samples repeatedly amplified pine DNA and were free of exogenous plant taxa. Pine DNA sequences of these samples showed a high degree of cytosine to thymine mismatches, typical of post-mortem damage. Stringent decontamination of wood surfaces combined with DNA metabarcoding and assessment of post-mortem DNA damage allowed us to authenticate ancient DNA retrieved from the oldest Late Glacial pine forest. These techniques can be applied to any subfossil wood and are likely to improve the accessibility of relict wood for genome-scale ancient DNA studies.

Department of Ecology and Genetics Evolutionary Biology Centre Uppsala University Norbyvägen 18D 75236 Uppsala Sweden

Department of Geography University of Cambridge Downing Place Cambridge CB2 3EN UK

Genetic Diversity Centre ETH Zurich Universitätstrasse 16 CH 8092 Zurich Switzerland

Global Change Research Centre Masaryk University 613 00 Brno Czech Republic

Swiss Federal Institute for Forest Snow and Landscape Research WSL Zürcherstrasse 111 CH 8903 Birmensdorf Switzerland

Citace poskytuje Crossref.org