Wood identification with PCR targeting noncoding chloroplast DNA

Wood identification is extremely important in the modern forest industry. It also has significant applications in forensics, as well as in archeology and ecological research. In this study, five universal primer pairs amplifying chloroplast noncoding sequences of 300–1,200 bp were designed. Sequencing these amplicons in combination can lead to reliable identification of logs and wood products to cultivar, ecotype, or even the falling population. These primer pairs work on both gymnosperms and angiosperm trees. They also are potentially applicable to accurately identify shrubs and herbaceous species. In addition, a wood DNA purification method is proposed in which N-phenacylthiazolium bromide (PTB) is used to increase the quality and quantity of extracted DNA. This method was first validated using air-dried timber disks from three different tree species that were felled 4 years ago. The sapwood and outer heartwood provided the best locations for DNA extraction. The method was also successfully applied to extract DNA from the recalcitrant processed white oak wood, randomly selected staves of wine barrels. The single nucleotide polymorphism detected on the oak DNA sequences showed correlation to their geographical origins.