基于DNA条形码和二级结构鉴定菟丝子及其易混伪品OA

Objective:To identify Cuscutae semen and its miscible counterfeit Cuscuta japonica choisy using DNA barcode ITS2 base sequence and its secondary structure.Methods:Ten samples of Cuscutae semen,five samples of Cuscuta australis R.Br.and five samples of Cuscuta japonica choisy were collected from the Bozhou herbal market in Anhui Province,China.After extracting genomic DNA,ITS2 sequence amplification primers were used for PCR and sequencing;and the ITS2 sequence of Cuscutae semen,Cuscuta australis R.Br.and Cuscuta japonica choisy were downloaded from GenBank.The sequences were compared and analysed using MEGA 11.0,and the intraspecific and interspecific genetic distances were calculated.The neighbor-joining(NJ)method was used to construct the phylogenetic clustering tree,and the ITS2 secondary structure was predicted through the database.Results:The NJ tree was formed by Cuscutae semen,Cuscuta australis R.Br.and Cuscuta japonica choisy,and each of them is clustered into one branch.The interspecific genetic distance based on ITS2 base sequence could accurately identify Cuscutae semen,Cuscuta australis R.Br.and Cuscuta japonica choisy.The secondary structure of Cuscutae semen,Cuscuta australis R.Br.and Cuscuta japonica choisy were quite different on the whole and could be distinguished obviously.Conclusion:Based on ITS2 sequences,Cuscutae semen and its miscible counterfeit can be accurately identified.