ITS2 sequence analysis of 5 medicinal plants of Cirsium
OBJECTIVE To identify the ITS2 sequences of 58 samples from 5 species of medicinal plants of Cirsium by DNA barcode technology,and to discuss the genetic relationship of medicinal plants of Cirsium.METHODS The total DNA was extracted from 58 samples of 5 species of Cirsium using the plant genome DNA extraction kit,and the ITS2 sequence was amplified by PCR and sequenced.The interspecific and intraspecific Kimura 2-parameter distances were calculated with Mega 7.0 to construct its neighbor-joining phylogenetic tree.RESULTS The ITS2 sequence length of five species of Cirsium medicinal plants was 227-228 bp,and the GC%content ranged from 59.65%to 63.60%.The maximum intraspecific genetic distance was 0.0089,and the interspecific genetic distance was 0.0179-0.0796.Through the secondary structure of ITS2 sequence,the number and size of stem rings in region Ⅰ and region Ⅲ can be effectively distinguished.NJ phylogenetic tree analysis showed that the genetic relationship between Cirsium esculentum and Cirsium vlassovianum is close.CONCLUSION ITS2 sequence can be used as DNA barcode sequence for identification of five medicinal materials of Cirsium.