基于ITS2序列鉴定苗药金铁锁及其混伪品

目的：本研究利用ITS2序列对苗药金铁锁及其混伪品进行鉴定研究，从而确保药材质量，保障临床用药安全。方法：提取金铁锁药材及其混伪品基因组DNA，PCR扩增并双向测序获得ITS2序列。所有序列经过CodonCode Aligner V3.7.1拼接后，采用MEGA5.1软件进行序列比对，计算种内和种间Kimura2-Parameter（K2P）遗传距离，并构建系统发育树。采用相似性搜索法、最近距离法、邻接（NJ）树法对ITS2序列鉴定能力进行评估。结果：金铁锁药材的ITS2序列长度为229 bp，其ITS2序列种内最大K2P遗传距离小于与混伪品的最小种间K2P遗传距离；应用相似性搜索法表明ITS2序列能够准确鉴定金铁锁药材及其混伪品；基于ITS2序列构建NJ树，金铁锁及其混伪品均表现出良好单系性，均能明显区分。结论：ITS2序列能够稳定、准确地鉴定金铁锁药材及其混伪品，DNA 条形码技术可为金铁锁药材及其混伪品的鉴定提供新的方法。

Identification of Psammosilene Radix and Its Adulterants by ITS2 Sequence

Psammosilene Radix is a famous miao national herb and it is rare and endangered nowadays. However, it is often confused with the root of Silene viscidula. In this study, the ITS2 regions was used to identify Psammosilene Radix and its adulterants. All DNA samples of Psammosilene Radix and its adulterants were extracted. The ITS2 regions were amplified and sequenced, and the final sequences were assembled using the CondonCode Aligner. The genetic distances were calculated by kimura 2-parameter (K2P) model and the Neighbor-Joining (NJ) phylogenetic trees were constructed using MEGA5.1.BLAST 1, the nearest distance and phylogenetic tree (NJ-tree)methods were used to assess the identification efficiency of the ITS2 region. Results indicated that the length of ITS2 sequences of Psammosilene Radix w 229 bp, the identification effficiency of ITS2 region using BLAST 1 was 100%;and the maximum intra-specific K2P distance were lower than the minimum inter-specific K2P distance. Additionally, the NJ tree based on ITS2 sequence indicated that Psammosilene Radix and its adulterants could be distinguished clearly. In conclusion, the ITS2 region as DNA barcodes could identify Psammosilene Radix and its adulterants stably and accurately. Furthermore, the application of ITS2 barcode in the identification of TCM has a good prospective.