Establishment of a two-tiered molecular identification system for Dracaena species - the source plants of dragon's blood.

BACKGROUND: The unresolved taxonomy of Dracaena species, the botanical sources of the prized traditional medicine Dragon's blood, poses significant challenges to resource conservation, material traceability, and quality control. This study aimed to resolve these taxonomic ambiguities by developing and validating a high-resolution, integrated molecular authentication system. Based on 26 original plant samples from the genus Dracaena, along with relevant DNA barcode loci retrieved from NCBI, five previously reported DNA barcodes were evaluated and assessed. Simple sequence repeat (SSR) sequences from the transcriptome of D. cambodiana were subsequently screened. Finally, the established DNA barcode and SSR molecular marker systems were applied to identify the botanical origin of Dragon's blood.

RESULTS: The trnP-psaJ and psbK-psbI regions were identified as optimal barcodes, effectively distinguishing foreign sources (D. cinnabari and D. draco) from domestic ones. From transcriptomic data, we screened and validated 16 highly polymorphic SSR primers. While DNA barcodes confirmed broad phylogenetic relationships, SSR markers provided superior resolution, clearly delineating the closely related domestic taxa D. cambodiana, D. cochinchinensis, and the "Yanzong" plant into distinct genetic clusters. A key finding was the consistent genetic distinctiveness of Hainan Island populations, supporting the genetic affinity of the Hainan populations with D. cambodiana, indicating that they fall within the genetic variation range of this species based on the available reference samples. Furthermore, cultivation analysis revealed that D. cambodiana is the predominant cultivated species in China; the horticultural variety "Heizhenzhu" was identified as a likely variant of this species, while "Taikongtie" showed ambiguous affinity, possibly involving D. cochinchinensis or Guangxi populations.

CONCLUSIONS: We established a novel, two-tiered molecular identification system that combines the trnP-psaJ barcode for rapid screening with a panel of 16 SSR markers for fine-scale discrimination. This integrated approach successfully clarifies the taxonomy of important Dragon's blood source plants. It provides a reliable, efficient protocol for authenticating Dracaena species and germplasm, offering a critical technical foundation for resource conservation, medicinal material standardization, and targeted breeding programs.