Genetic polymorphism of medicinally-used Codonopsis species in an internal transcribed spacer sequence of nuclear ribosomal DNA and its application to authenticate Codonopsis Radix

Codonopsis Radix has been prescribed as the roots of Codonopsis pilosula, C. pilosula var. modesta and C. tangshen in Chinese Pharmacopoeia. In order to find out genetic markers for identifying the 3 taxa and to authenticate Codonopsis Radix, the molecular analysis of the internal transcribed spacer sequence of nuclear ribosomal DNA was conducted on Codonopsis plants collected widely from Gansu Prov. and Chongqing city of China, the main producing areas of Codonopsis Radix. Significant genetic polymorphism was observed, represented by 11 types of ITS sequences in C. pilosula, 5 types in C. pilosula var. modesta and 5 types in C. tangshen. Among the determined sequences, 1, 1 and 2 types were thought to be of pure lines of each taxon, respectively, designated as types P0, PM0, T1 and T3, and the rest might be derived from hybridization. Hybrid lines were inferred to be resulting from the combination of these pure lines. The informative sites for discriminating the 3 taxa were detected at the nucleotide positions 122nd, 226th, 441st and 489th from upstream of the ITS sequence. For discrimination of the types of C. tangshen, including one type T0 registered in GenBank, the nucleotides at positions 135th, 489th and 500th were informative. Botanical sources of the crude drugs produced in a wide range of the southeast Gansu Prov. were C. pilosula, just those from Wenxian of Gansu Prov. were C. pilosula var. modesta. The crude drugs produced in Chongqing were derived from C. tangshen.