Phylogenetic relationship of six Glycyrrhiza species based on rbcL sequences and chemical constituents.

The nucleotide sequences of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbcL) of Glycyrrhiza glabra, G. uralensis, G. inflata, G. echinata, G. macedonica and G. pallidiflora have been determined to construct their phylogenetic tree. Based on these sequences, the six Glycyrrhiza species were divided into two groups: three, G. glabra, G. uralensis, and G. inflata, which produce glycyrrhizin as a major saponin, and the others, G. echinata, G. macedonica and G. pallidiflora, which produce macedonoside C as a major saponin. Among the three glycyrrhizin-producing species, only two nucleotide substitutions were observed between the rbcL sequences of G. glabra and G. uralensis, and the sequence of G. uralensis was identical to that of G. inflata, indicating that G. uralensis and G. inflata are closely related. Among the three macedonoside C-producing species, only one nucleotide substitution was observed between those of G. echinata and G. macedonica, indicating that these two species are also closely related.