DNA barcoding research and its application on medicinal plants of Bletilla H. G. Reichenbach

To identify adulterants from medicinal plants of Bletilla H. G. Reichenbach, the suitable candidate DNA barcoding of Bletilla was evaluated. In this study, the internal transcribed spacer (ITS) of nuclear ribosomal DNA, the LFY homologous gene intron 2 and chloroplast ycf1 gene were amplified and sequenced from forty-one samples. The intra-specific and inter-specific divergences of Bletilla were calculated, and the identification efficiency was assessed using Barcoding Gap, NJ tree by K2P distance and BLAST1 method. The result showed the intra-specific divergence of nrDNA ITS and ycf1 (0.022-0.106 and 0.017-0.106) were obviously higher than the inter-specific divergence (0-0.012 and 0-0.015), and four species of Bletilla were also accurately distinguished in NJ trees. Whereas, there was no Barcoding Gap on LFY homologous gene intron 2, thus it cannot effectively identify species of Bletilla. Using NJ tree of nrDNA ITS and ycf1 gene, powdery medicine and the adulterants of Bletilla were successfully unidentified. In conclusion, nrDNA ITS and ycf1 can be used as a potential DNA barcoding to identify the medicinal plants in Bletilla and its adulterants. There were only three basic differences on nrDNA ITS between "Jujing baiji" and Bletilla striata of Lu'an in Anhui province, and two basic differences in ycf1. Based on morphological and molecular data, "Jujing baiji" could be recognized as the species of Bletilla striata.