基于DNA条形码技术探讨板蓝根及大青叶基原物种问题

Discussion on the botanical origin of Isatidis Radix and Isatidis Folium based on DNA barcoding

本文对我国板蓝根及大青叶原植物的物种进行了探讨,以澄清分类上的混乱现象。利用PCR直接测序法对采集的全国22份样本,测定了核基因ITS2区和叶绿体matK基因片段,所得序列经CodonCode Aligner拼接后,用软件MEGA4.0进行相关数据分析,并构建NJ(邻接)树。结果表明,所研究样本ITS2片段长度为191 bp,测序峰图显示不同研究样本间具有多个单核苷酸多态性(SNP)位点,部分样本具有杂合位点;从构建的NJ树图可以看出,基于核ITS2片段,所研究样本被分成两大支,其中一支与欧洲菘蓝相聚。基于叶绿体matK序列,所研究样本也被明显分成两支。因此本研究支持板蓝根及大青叶的原植物为菘蓝(Isatis indigotica Fortune),与欧洲菘蓝(Isatis tinctoria L.)是独立的两个物种,不支持Flora of China中将二者合并的观点。

This paper aimed to investigate the botanical origins of Isatidis Radix and Isatidis Folium, and clarify the confusion of its classification. The second internal transcribed spacer （ITS2） of ribosomal DNA, the chloroplast marK gene of 22 samples from some major production areas were amplified and sequenced. Sequence assembly and consensus sequence generation were performed using the CodonCode Aligner. Phylogenetic study was performed using MEGA 4.0 software in accordance with the Kimura 2-Parameter （K2P） model, and the phylogenetic tree was constructed using the neighbor-joining methods. The results showed that the length of ITS2 sequence of the botanical origins of Isatidis Radix and Isatidis Folium was 191 bp. The sequence showed that some samples had several SNP sites, and some samples had heterozygosis sites. In the NJ tree, based on ITS2 sequence, the studied samples were separated into two groups, and one of them was gathered with lsatis tinctoria L. The studied samples also were divided into two groups obviously based on the chloroplast matK gene. In conclusion, our results support that the botanical origins of Isatidis Radix and Isatidis Folium are 1saris indigotica Fortune, and 1saris indigotica and Isatis tinctoria are two distinct species. This study doesn＇t support the opinion about the combination of these two species in Flora of China.