DNA barcoding for identification of the endangered species Aquilaria sinensis: comparison of data from heated or aged wood samples

Aquilaria sinensis (Lour.) Gilg is an evergreen tree and produces agarwood used for incense and as a uniquely precious medicine. It is in danger of disappearing due to illegal logging and its identification and protection is crucial. However, it is difficult or impossible to distinguish A. sinensis from other species of the genus Aquilaria Lam. and its closely related genus Gyrinops Gaertn. based on wood anatomical characteristics. Probably, DNA barcoding technology might provide an improvement in species identification. In this study, wood samples were tested, which were submitted to high-temperature drying and were stored for a long period in a xylarium. The factors should be identified that hinder the efficiency of wood DNA extraction from this species. The results indicate that the DNA from the wood tissues could be successfully amplified, apart from some DNA regions from the heartwood of the dried samples and the xylarium samples. The DNA sequences from the wood tissues mostly matched with the sequences of A. sinensis deposited in the GenBank. Moreover, analyses of phylogenetic trees based on trnL-trnF and ITS1 regions indicated that the wood tissues in the tests clustered together with the A. sinensis species from the GenBank, with bootstrap values of 74% and 94%, respectively. Consequently, it is feasible to identify A. sinensis wood on a species level based on the DNA barcoding technology.