DNA条形码在黄精属药用植物鉴定与遗传多样性分析中的应用

Application of DNA barcodes in identification and genetic diversity analysis of medicinal plants of the genus Polygonatum

黄精属(Polygonatum)的许多物种具有重要的药用价值,但目前缺乏能够准确、高效地鉴定黄精属药用植物的DNA条形码。本研究通过对ITS、trnK-matK、rbcL、psbA-trnH和psbK-psbI序列进行扩增和测序,并从ITS序列中提取ITS2序列,共获得黄精属7个药用物种23份样品的138条序列。进一步比较6个DNA条形码对黄精属药用植物的鉴定效率,并验证所筛选条形码的可靠性。结果显示:trnK-matK的种内和种间变异重合少且有较明显的条形码间隙,其他5个序列的种内和种间变异重合多且无条形码间隙;BLAST结果表明trnK-matK的鉴定效率最高(85.7%),系统发育树显示trnK-matK的鉴定能力最强,能将全部12个多花黄精样品聚在一支,并能区分黄精、滇黄精、玉竹、点花黄精和湖北黄精;AMOVA分析结果揭示trnK-matK的群体遗传分化指数(F_(st))最高,适用于区分黄精属物种间差异。因此,trnK-matK最适用于黄精属药用植物的分子鉴定。

Many species of the genus Polygonatum have important medicinal value,but there is currently a lack of DNA barcodes that can effectively identify medicinal plants within Polygonatum.In the present study,based on the amplification and sequencing of ITS,trnK-matK,rbcL,psbA-trnH,and psbK-psbI,and the extraction of the ITS2 sequences,138 sequences were obtained from 23 samples of seven Polygonatum medicinal species.Similarity search algorithm(BLAST)and neighbor-joining(NJ)analysis were used to compare the efficacy of sequences for identifying medicinal species and analysis of molecular variance(AMOVA)was applied to verify the reliability of the screened barcodes.Results demonstrated that the intra-and inter-specific genetic variation of trnK-matK showed less overlap and an obvious barcoding gap,while the other five sequences showed considerable overlap and no barcoding gaps.The BLAST search results showed that trnK-matK had the highest identification efficiency(85.7%).The phylogenetic trees also showed that trnK-matK had the most efficient identification ability,clustering all 12 samples of P.cyrtonema together and distinguishing P.sibiricum,P.kingianum,P.odoratum,P.punctatum,and P.zanlanscianense.AMOVA revealed that trnK-matK had the highest population genetic differentiation index(F_(st))and was the most suitable for distinguishing differences between Polygonatum species.Therefore,among the six candidate barcodes,trnK-matK is the most suitable for molecular identification of medicinal plants of Polygonatum.