Molecular identification of original plants of Spica prunellae based on ITS sequence

The ITS sequences of the original plants of Spica prunellae and its confusable species including 16 individuals belonging to 6 species from 12 localities, were analyzed. The results showed that the length of ITS sequences was 584 bp after alignment and the overhanging terminals were cut. When alignment gaps were treated as missing data, there were 150 variable sites. The percent divergence between species was 10.9%, with a transitions/transversions ratio of 1.53. There were 11 variable and 9 informative sites among the ITS sequences of 4 species in Prunella Linn. There were specific sites at 5, 474 and 525 nt of the ITS sequence of P. grandiflora. There were 122 specific sites between genus Ajugaand genus Prunella. Both phylogenetic trees constructed by Maximum parsimony method and Neighbor-Joining method indicated that Prunella vulgarisLinn., P. asiatica Nakai. and P. hispida Benth. had a very close relationship. The character of ITS sequences can be used for providing the molecular markers for identifying Chinese Prunella (S. prunellae).   Key words: Prunella vulgaris Linn, Prunella asiatica Nakai, ITS sequence, molecular identification.