A DNA barcode reference library for CITES listed Malagasy Dalbergia species

Abstract

On Madagascar, the illegal and unsustainable exploitation and illegal international trade of Dalbergia (rosewood) precious woods remain a serious conservation problem.Members of this genus are at high risk of extinction as a consequence of logging, mining, and slash and burn agriculture. Morphological identification of these Malagasy species is difficult in the absence of flowers and fruits, especially in the case of cut trees, sawn wood, and finished product. In this study, we use molecular barcoding to identify the Dalbergia species with the intent to contribute to the control of their illegal trade. Thirty-six Dalbergia samples representing 12 Malagasy species of which 11 have high commercial value, were collected to test the efficacy of a region of the plastid genome (rbcL) and a nuclear-transcribed ITS for barcoding. These widely used markers, as well as DNA barcoding gaps, "best match" and "best close match" approaches, and the neighbor-joining method were employed. All samples were amplified and sequenced using the two markers. Using a single locus, the "best match" and "best close match" approaches revealed that ITS has high discriminatory power within the tested Malagasy species. The combination of rbcL + ITS revealed 100% species discrimination. This study confirms that ITS alone and in combination with chloroplast barcode rbcL allow non-ambiguous identification for the 12 species studied. The results contribute to the development of DNA barcoding as a useful tool to identify Malagasy Dalbergia and suggest that the approach developed should be expanded to all 56 potentially exploited species in reference to international CITES requirements and the sustainable management of valuable resources.

The DNA barcode identification of Dalbergia odorifera T. Chen and Dalbergia tonkinensis Prain

“…In the study of Dalbergia species, Yu et al analyzed 8 barcode sequences and their combinations of 9 species of this genus and found that the combined sequences had higher identification power than any single sequence [ 26 ]. Similarly, other researchers also proposed the combined sequence as the DNA barcodes for this genus [ 25 , 40 , 44 ]. However, the combination of sequences as DNA barcodes did not attract much attention in the studies of D. odorifera and D. tonkinensis , and the researchers tested only the identification abilities of single sequences in the studies of the two species [ 15 ].…”

Identification and validation of ITS2-specific universal primers for DNA barcoding in plants

“…ITS2 F -GGGGCGGATATTGGCCTCCCCTTG ITS2 R -GACGCTTCTCCAGACTACAAT (Saidon et al, 2023) 3. ITS2 F -ATGCGATACTTGGTGTGAAT ITS2 R -TCCTCCGCTTATTGATATGC (Rakotonirina et al, 2023) 4. ITS2 F -ATGCGATACTTGGTGTGAAT ITS2 R -GACGCTTCTCCAGACTACAT (Nasarodin et al, 2023) 5.…”