Objective: To explore the formation mechanism of genuineness of Glycyrrhiza uralensis. Method: Searching for beta-amyrin synthase(β-AS) gene in Genbank and finding out the conserved region by sequence alignment

then primers were designed by primer premier 5.0 software. β-AS genes of G. uralensis from 3 different origins were amplified and sequenced

which were analysed by MegAlign software. In the differential expression experiment

the total RNA of G. uralensis from 3 different origins were extracted

then cDNA were obtained by reverse transcription. Using 18S gene of G. uralensis as internal reference

relative expression of β-AS genes of G. uralensis from 3 different origins were detected and analysed. Result: The gene polymorphism experiment showed that 108 variable sites were expresent in the nine samples

and the quantity of variable sites of intron was twice than that of exon. The differential expression experiment showed that the average relative expression of β-AS gene of G. uralensis from different origins was significantly different. Conclusion: The differences of gene polymorphism and expression of β-AS gene in G. uralensis from different origins may be one of the important reasons to result in the genuineness of G. uralensis.