[Identification of medicinal plants used as Tibetan traditional medicine Chuan-Bu based on nrDNA markers].

Objective: To identify the common Tibetan herb Chuan-Bu.

Method: Local herbalists were visited to observe which plants were being used as Chuan-Bu. Samples of the indigenous plants were collected at the same time. Leaf materials were collected from field surveys. Total genomic DNA was extracted from silica gel-dried leaf samples. The PCR products were purified and directly sequenced.

Result: As the origin of Chuan-Bu in Tibet autonomous region was authenticated, two species were determined, i. e. Euphorbia stracheyiand E. wallichii. Also, based on our earlier research, the origin of Chuan-Bu in Gansu province, is from E. kansuensis. The sequences of ITS1 for E. stracheyi and E. wallichii were 261 bp in size, and 221 bp in ITS2, respectively. The size of the 5.8S coding region was 164 bp for all species examined in the genus. Especially, there was a heterozygous locus in ITS1 (C/G; position 72) for E. stracheyi. The nucleotide divergence between sequences of the 6 species in pairwise comparisons was calculated and the result showed that the variable site could be detected in each pairwise comparison of sequences. Also, there were 8 point mutations in the 5.8S coding region.

Conclusion: nrDNA ITS sequences can be used as the molecular markers to identify the Tibetan herb Chuan-Bu and such Traditional Chinese Medicines from the same genus Euphorbia as E. lathyris, E. humifusa and E. pekinensis.