基于ITS2序列鉴定川贝母及其混伪品基原植物

摘要

To discriminate original plants of Fritillariae Cirrhosae Bulbus and its adulterants using ITS2 sequence as a DNA barcode. Fritillaria specimens of Fritillariae Cirrhosae Bulbus were collected. Their ITS2 sequences were extracted, amplified by PCR, and sequenced bidirectionally. Sequences were assembled by CodonCode Aligner. ITS2 sequences of adulterants were downloaded from CenBank. The intra-specific and inter-specific K-2-P distances of ITS2 sequences of the original plants were calculated, and N-J tree was constructed by MEGA V 4.1. Besides that, with the web tool established by Schultz etc., ITS2 secondary structures were predicted. The maximum intra-specific K-2-P distance was 0.0276, while the minimum inter-specific K-2-P distance was 0.0583. Different samples of Fritillariae Cirrhosae Bulbus and their original plants were gathered together and could be distinguished from their adulterants by N-J tree. Furthermore Fritillariae Cirrhosae Bulbus could also be differentiated obviously from its adulterants by their ITS2 secondary structure. ITS2 sequences exhibit their ability to discriminate Fritillariae Cirrhosae Bulbus and its adulterants. This barcode is an efficient molecular identification method.%本研究对川贝母5种不同基原植物ITS2序列进行PCR扩增和测序；同时扩大研究范围,从GenBank上下栽川贝母及其常见混伪品共10个物种13个样本的ITS2序列.用MEGA4.1计算其种间、种内的K-2-P距离,并分析各样本间ITS2序列二级结构的差异,最后利用ITS2序列重构其系统发育树.结果显示川贝母基原植物种内最大K-2-P距离为0.0276,与混伪品的种间最小K-2-P距离为0.0583:川贝母及其混伪品的ITS2二级结构存在明显差异；重构的系统发育树显示川贝母不同基原物种聚为一支,能较好与混伪品区分.研究结果表明ITS2条形码序列能够成功鉴定川贝母及其混伪品的原植物,为川贝母混伪鉴别提供了新工具.