Identification of cortex herbs using the DNA barcode nrITS2.

To discriminate the cortex herbs of Chinese Pharmacopoeia, the second internal transcribed spacer (ITS2) of ribosomal DNA of 51 samples belonging to 19 kinds of cortex herbs were analyzed in this paper. Sequence assembly was performed using the CodonCode Aligner. Phylogenetic study was performed using the molecular evolutionary genetics analysis (MEGA) 4.0 software in accordance with the Kimura 2-Parameter (K2P) model. Phylogenetic tree was constructed using the neighbor-joining (NJ) method. We found that the ITS2 sequences of the studied samples ranged from 207 to 256 bp in length and easy to be amplified. The intraspecific genetic distance of the cortex herbs was between 0 and 0.073, which was lower than their interspecific genetic distance (mean, 0.868; minimum, 0.101). In the cluster dendrogram, all the studied medicinal materials with several samples, were monophyletic. It is concluded that ITS2 barcode is suitable for the identification of cortex herbs of Chinese Pharmacopoeia, and it will play an important role in the field of identification of traditional Chinese medicine (TCM).