Identification of Genetic Relationships between Medicinal Licorices Based on ITS2 Sequences / 中国药学杂志

ABSTRACT

OBJECTIVE: To obtain the genetic information of 181 domestic and foreign licorice samples by determining the internal transcribed spacer sequence 2 (ITS2) in order to clarify their phylogenetic relationships and differentiate the medicinal licorice species from the non-medicinal ones. METHODS: Genomic DNA was first extracted from licorice samples of different origins and habitats. Then, the ITS2 sequences were amplified using PCR technique. Next, the ITS2 sequences were subjected to sequence analyses and neighbor-joining(NJ) tree analysis. Finally, the analytical method based on ITS2 DNA barcodes was established for the licorice species discrimination. The method was then applied to the phylogenetic analysis among the suspected domestic mutants, foreign licorice samples and domestic medicinal licorices, in addition to the discriminations of the medicinal and non-medicinal licorices. RESULTS: The medicinal licorice could be explicitly separated from the two commonly encountered non-medicinal licorice species either by using ITS2 sequence analysis or NJ tree analysis; and the suspected domestic mutants and foreign licorice samples converged with the medicinal licorice to form one monophyletic branch in the NJ tree analysis, which indicated unambiguously conspecifics. CONCLUSION: This study establishes a method for discrimination of medicinal and non-medicinal licorices based on ITS2 barcodes; and by the advantage of this method, the conspecific relationships among the suspected domestic mutants, foreign licorice samples and Chinese medicinal licorice are clarified. Thus a theoretical reference to the expansion of medicinal licorice resources and assurance of the safety and efficacy of the clinical licorice medications are provided.