基于居群DNA条形码的药用植物黄芩的产地鉴别研究

目的:利用居群DNA条形码阐明不同产地(居群)黄芩的遗传分化程度,对其进行产地鉴别。方法:应用进化速率快和母系遗传的叶绿体DNA基因间序列,基于分子谱系地理学理论筛选出居群间遗传分化明显的片段,构建单倍型网状进化树,根据单倍型在网状进化树中的位置、出现的频率和地理分布范围的大小,划分出不同层次的居群DNA条形码,以用于地理分布范围宽窄不同的产地鉴别。结果:本实验筛选出3个叶绿体DNA基因间序列atpB-rbcL,trnL-trnF和psbA-trnH对17个黄芩野生居群进行分子谱系地理学分析,得到13个多态位点,共20个单倍型,其中3个分布最广、频率最高的单倍型可用于较广地域的产地鉴别,称为区域居群DNA条形码;3个分布次之、只存在于2～3个邻近居群的单倍型可用于较窄地域的产地鉴别,称为地区居群DNA条形码;另有8个仅局限在某一个居群的单倍型可用于特定居群的鉴别,称为居群特有DNA条形码。结论:叶绿体基因间序列在居群间存在明显遗传分化,可用于地理分布范围宽窄不同的黄芩产地鉴别。

Locality identification of Chinese medicinal plant Scutellaria baicalensis (Lamiaceae) population-level DNA barcoding

Scutellaria baicalensis is an important traditional Chinese medicine and Scutellaria flavonoids have received worldwide attention in recent years. It is the basis of controlling quality of S. baicalensis to develop a reliable genetic marker system used to identify locality of origin. Because of the characteristics of maternal inherited and high-rate of evolution, the cpDNA intergenic spacer can effectively elucidate the degree of genetic variation in different areas of the same species (populations), which can be used as the population-level DNA barcoding to locality identify. In this study, we have used the molecular phylogeography analysis for the three cpDNA intergenic spacers atpB-rbcL, trnL-trnF and psbA-trnH of 17 wild populations from different localities, which reveals the 20 haplotypes, including 13 polymorphic sites and constitutes a shallow gene tree. The authers have divided the haplotypes of S. baicalensis into three grades of population-level DNA barcoding according to the frequence and geographic distribution: 3 highest-frequency haplotypes as area-population-level DNA barcoding, 3 haplotypes were mainly shared by 2-3 adjacent populations as region-population-level DNA barcoding, and there are also 8 unique-population haplotypes as unique-population-level DNA barcoding. The result of this study reveals that population-level DNA barcoding is a reliable genetic marker used to locality identify of S. baicalensis.