Molecular Identification of Tibetan Herbs and Their Closely Related Species in Family Compositae

OBJECTIVE To evaluate the ability of ITS2(internal transcribed spacer 2) sequence as a DNA barcode to identify Tibetan herbs and their closely related species in family Compositae.METHODS A total of 50 plant samples of 26 species distributed in 8 genera of family Compositae were collected from Tibet Autonomous Region and other places.Most of these plant species were Tibetan herbs.The Distance-Based Method and Tree-Based Method were used to evaluate the identification ability of ITS2 sequence.First,the genomic DNAs were extracted by kit.The ITS2 sequences were amplified and bi-directional sequenced.The rDNA sequences containing the ITS2 regions of 26 species were downloaded from the GenBank database.After these sequences were spliced and assembled by CodonCode Aligner v.9.0.1 software,MEGA 11.0.10 software was used to construct the NJ phylogenetic tree,and TaxonGap v.2.4.1 software was used to analyze the intra-species and inter-species variation.RESULTS Using the Distance-Based Method and the Tree-Based Method,ITS2 sequence could successfully identify Artemisia sieversiana from 3 species in Artemisia genus,Aster poliothamnus from 6 species in Aster genus,Cremanthodium ellisii and Cremanthodium lineare from 2 species in Cremanthodium genus,Saussurea superba from 3 species in Saussurea genus.It could also distinguish Ixeridium chinense from Ixeridium gramineum,identify Leontopodium stracheyi and Parasenecio deltophyllus from other species.ITS2 sequence could distinguish 9 species from 26 Compositae species with 34.6% identification efficiency.CONCLUSION ITS2 can be used for the rapid and accurate identification of Tibetan herbs and related species in family Compositae.