Polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP) and Amplification Refractory Mutation System (ARMS) analyses of medicinally used Rheum species and their application for identification of Rhei rhizoma

Previously, we have determined marker nucleotides on the chloroplast matK gene to identify Rheum palma-tum, R. tanguticum and R. officinale used as Rhei Rhizoma officially. In the present study, we further developed a convenient and efficient identification method on the basis of marker nucleotides with Amplification Refractory Mutation System analysis. On the basis of the nucleotide substitutions at positions 367 and 937 among the three species on the matK gene, at each position two kinds of reverse primers with complementary 3'-terminal nucleotides were designed. Upon PCR amplification using three sets of primers and template DNA from each species, one or two fragments (202 bp or/and 770 bp) were detected. As the resultant three fragment profiles were species-specific, the procedure enabled us to classify the botanic origins of 22 drug samples of Rhei Rhizoma.