Species identification of licorice using nrDNA and cpDNA genetic markers

For the accurate identification of medicinal licorice species, nucleotide sequences of four types of DNA regions were researched for 205 specimens, including three species used as licorice: Glycyrrhiza uralensis, Glycyrrhiza glabra, and Glycyrrhiza inflata. The four DNA regions were the internal transcribed spacer (ITS) on nuclear ribosomal DNA, the rbcL gene, the matK gene, and the trnH-psbA intergenic region on chloroplast DNA (cpDNA). Ten genotypes were consequently recognized as combinations of the sequence data obtained from the four DNA regions. Species-specific genotypes were defined from the frequency of the appearance of species in each genotype and from the phylogenetic relationships of the 10 genotypes. This revealed the possibility of identifying licorice species based on the 10 genotypes. Next, comparison of species identifications by each DNA region suggested that efficient identification of licorice species is possible using the genetic information obtained from the ITS and trnH-psbA intergenic region. Additionally, concerning the phylogenetic relationships of the Glycyrrhiza species used as licorice, it is suggested from the genetic information of the four types of DNA regions that G. glabra is more closely related to G. inflata than to G. uralensis. In the G. uralensis examined, four genotypes were recognized as intra specific variations. The appearance frequency of each genotype in G. uralensis differed according to the area in China. G. uralensis may have expanded its distribution areas from western to eastern China because many licorices with the phylogenetic ancestral genotype were observed in western areas, while many with the derivative genotype were observed in eastern areas.