Dalbergia is popularly known as rosewood or Hongmu in Chinese in reference to its fragrance. Rosewoods are renowned for their density, beauty, nonporous nature, and exceptional mechanical and acoustic properties. Many rosewood species experience high extinction threats, because they are among the most heavily trafficked natural resources in the illegal wildlife trade.
Therefore, it is quite important to develop a powerful and universal approach for rosewood identification, so as to conserve rosewood species threatened by illegal logging and help devise effective conservation strategies.
In a study published in Botanical Journal of the Linnean Society, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) established a DNA barcoding approach for rosewoods by utilizing whole-chloroplast genome sequences, either as super-barcodes or as sources to identify short but highly informative DNA barcoding regions.
The researchers generated 81 rosewood plastomes representing 28 Dalbergia species and established a phylogenomic dataset including a total of 110 accessions representing 31 species. A total of 4542 chloroplast microsatellites (SSRs) were identified across the 81 Dalbergia plastomes.
The researchers found that Dalbergia plastomes are highly conserved, with no major gene losses or variations. They revealed three main clades in the phylogenetic tree, each supported by high bootstrap values. They successfully distinguished some closely related and previously ambiguous species that are difficult to differentiate using morphological characters and were not clearly distinguished in earlier studies. They differentiated the rosewood types, with black rosewood forming a sister relationship within the scented rosewood group.
Furthermore, they detected a broad range of long repeats across each Dalbergia sample, ranging from 30 to 287 bp. They identified potential positive selection in specific chloroplast genes within Dalbergia, namely, ycf2, accD, ycf1, and matK.
The results demonstrated that plastome-derived DNA barcodes are powerful tools for species identification within the genus Dalbergia. The approach provides the prospect of developing a highly valuable tool for the conservation of threatened rosewoods by enabling the reliable identification of rosewood fragments in the commercial timber trade.
“Therefore, we propose using the entire plastome as a super-barcode or local mini-barcode for precise species identification, which will facilitate effective management and conservation of rosewoods,”said LIU Hongmei of XTBG.
First published: 26 December 2024
