Novel perspectives in wood certification and forensics: dry wood as a source of DNA

The importance of wood for human societies can hardly be understated. If dry wood were amenable to molecular genetic investigations, this could lead to major applications in wood forensics, certification, archaeology and palaeobotany. To evaluate the potential of wood for molecular genetic investigations, we have attempted to isolate and amplify, by PCR, DNA fragments of increasing size corresponding to all three plant genomes from different regions of 10 oak logs. Stringent procedures to avoid contamination with external DNA were used in order to demonstrate the authenticity of the fragments amplified. This authenticity was further confirmed by demonstrating genetic uniformity within each log using both nuclear and chloroplast microsatellites. For most wood samples DNA was degraded, and the sequences that gave the best results were those of small size and present in high copy number (chloroplast, mitochondrial, or repeated nuclear sequences). Both storage conditions and storage duration play a role in DNA conservation. Overall, this work demonstrates that molecular markers from all three plant genomes can be used for genetic analysis on dry oak wood, but outlines some limitations and the need for further evaluation of the potential of wood for DNA analysis.