Exploratory application of DNA barcode analysis to aged softwood samples: insights into a robust protocol

Wood identification is an important aspect for understanding the historical and geographical background of ancient wooden materials. One of the major methods for wood identification is the anatomical inspection of its morphological data from a micrograph of the thin section or volumetric X-ray CT data, while another effective method is DNA (deoxyribonucleic acid) barcode analysis. This study aimed to establish a DNA barcode analysis protocol for aged softwoods. For this purpose, we performed a DNA barcode analysis using “authentic” samples deposited in xylarium. Two measures were implemented in this study: (i) polymerase chain reaction (PCR) amplification of a shorter marker region and (ii) physical separation of the rooms for DNA extraction and PCR amplification. Notably, the latter addressed the issue of inconsistent identification results across analyses. However, incorrect identification is sometimes obtained, indicating that further improvements to the protocol are still required. Nonetheless, this study advances the DNA barcode analysis protocol for wood identification by highlighting the need to eliminate external DNA contamination. In summary, our findings clarify the requirements for a reliable wood-identification protocol based on DNA barcodes and lay the foundation for a more robust procedure.