Dalbergia, colloquially known as rosewood or Hongmu in Chinese due to its fragrance, is esteemed for its density, aesthetic appeal, nonporous structure, and superior mechanical and acoustic attributes. Numerous rosewood species face heightened risks of extinction, as they are among the most frequently trafficked natural resources in the illegal wildlife trade.
Consequently, devising a robust and universal method for rosewood identification is imperative to aid in the conservation of these endangered species and to formulate effective preservation strategies.
In a study published in Botanical Journal of the Linnean Society, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences introduced a DNA barcoding technique for rosewoods, employing whole-chloroplast genome sequences either as super-barcodes or as sources for pinpointing concise yet richly informative DNA barcoding regions.
The researchers assembled 81 rosewood plastomes from 28 Dalbergia species and created a phylogenomic dataset comprising 110 accessions from 31 species. Across these 81 Dalbergia plastomes, they identified 4542 chloroplast microsatellites (SSRs).
Their observations indicated that Dalbergia plastomes exhibited high conservation, devoid of significant gene losses or variations. Phylogenetic analysis unveiled three primary clades, each bolstered by robust bootstrap values.
The researchers adeptly distinguished several species that were previously challenging to differentiate based on morphological traits and were not distinctly addressed in prior studies. Notably, they clarified the classification of rosewood types, with black rosewood emerging as a sister branch within the scented rosewood grouping.
In addition, they discovered a wide variety of long repeats in each Dalbergia sample, with lengths ranging from 30 to 287 base pairs. They also found evidence of potential positive selection in certain chloroplast genes specific to Dalbergia, including ycf2, accD, ycf1, and matK.
The findings indicated that DNA barcodes derived from plastome are effective tools for species identification within the Dalbergia genus. This methodology presents the potential for creating an invaluable tool for the preservation of endangered rosewoods, by ensuring the accurate identification of rosewood fragments in commercial timber trade.
“Therefore, we suggest utilizing the entire plastome as a comprehensive barcode or localized mini-barcode for precise species identification, thereby promoting effective management and conservation of rosewoods,”said LIU Hongmei of XTBG.
Published： 26 December 2024
