鉴别元宝草和贯叶金丝桃DNA条形码的筛选研究OA

Objective:To screen and determine the DNA barcode sequences suitable for the identification of Hypericum sampsonii and Hypericum perforatum and seek feasible molecular identification method to help solve the morphological identification difficulties of Hypericum sampsonii and Hypericum perforatum.Methods:Twenty samples of Hypericum sampsonii and Hypericum perforatum were col-lected from various places.Genomic DNA was extracted.DNA barcoding universal primers ITS2,matK,psbA-trnH and rbcL were select-ed.Each sample was amplified according to the standard procedure.The genetic distances within and between species were calculated u-sing the Kimura-2-Parameter model(K2P),and the phylogenetic tree was constructed by the Neighbor-joining method.The ViennaRNA Web Services database was applied to predict the secondary structure of the candidate sequence.Results:The rbcL,psbA-trnH and ITS2 sequences were all amplified successfully and the sequencing success rate reached 100%.After comparison,it was found that the ITS2 sequence had the most variant sites and a higher interspecific K2P distance,which could distinguish between Hypericum sampsonii and Hypericum perforatum.In addition,there were significant differences in the secondary structures of ITS2,psbA-trnH and rbcL sequences between Hypericum sampsonii and Hypericum perforatum.Conclusion:ITS2 sequence is the preferred DNA barcode for the identification of Hypericum sampsonii and Hypericum perforatum,while psbA-trnH sequence can be used as an auxiliary identification barcode.The combination of two can effectively achieve the authenticity identification of the species of Hypericum sampsonii and Hypericum perfora-tum.