党参及其易混伪品的ITS2分子鉴定

摘要

目的:对中药党参及其易混伪品进行ITS2条形码鉴定,探讨ITS2条形码序列对党参及其伪品鉴定的可行性.方法:对党参样品进行DNA提取、PCR扩增和双向测序,用CodonCode Aligner3.7.1进行序列拼接,MEGA4.1计算党参基原植物及其易混伪品的种间、种内的K2P距离,并采用P距离法建立N-J树,利用Koetschan等建立的ITS2数据库预测ITS2二级结构.结果:党参基原植物种内平均K2P距离均值为0.0339,与易混伪品的种间平均K2P距离为0.2688,党参的3个基原聚在一起,与易混伪品明显区分.党参与其易混伪品的ITS2二级结构Helix Ⅰ和Ⅲ区存在明显差异.结论:ITS2条形码序列能够鉴定党参及其易混伪品,为党参及其混伪品的鉴定提供了新思路.%This study aimed to discriminate between Codonopsis Radix and its adulterants by using ITS2 barcode sequence. DNA was extracted from Codonopsis Radix specimens. The ITS2 barcode was amplified by PCR and sequenced bidirectionally. Sequence assembly and generation of consensus sequence were conducted by using the CodonCode Aligner. The interspecific divergence and intraspecific variation of 'and its adulterants were computed.And then N-J tree was constructed by MEGA V4. 1. The ITS2 secondary structures were predicted by database which was established by Koetschan et al. Results showed that the average interspecific K2P distance of Codonopsis Radix was 0.2688, while the intraspecific was 0.0339. N-J tree revealed that different sources of Codonopsis Radix clustered and its adulterants were obviously distinguished. Codonopsis Radix was differentiated from its adulterants in helix I and helix III of the ITS2 secondary structure. It is concluded that ITS2 barcode sequence can be used to distinguish Codonopsis Radix from its adulterants.