基于叶绿体psbA-trnH基因间区序列鉴定肉苁蓉属植物

肉苁蓉的干燥肉质茎是常用中药材, 药典收录基源植物有管花肉苁蓉和荒漠肉苁蓉两种, 但是市场上经常会与黄花列当、草苁蓉、盐生肉苁蓉及沙苁蓉等混用。本文对不同类群肉苁蓉及混淆品的叶绿体psbA-trnH基因间区进行PCR扩增并测序, 获得了该区间的完整序列, 用K-2P法建立了系统进化树, 聚类结果与形态分类相符。所得结果显示, psbA-trnH片段序列在肉苁蓉及混淆品种间存在丰富的变异, 肉苁蓉属各种的种间遗传距离从0.077% 到0.743%, 种内遗传距离从0% 到0.007%, 种内和种间存在明显的“barcoding gap”。肉苁蓉属各种与黄花列当的遗传距离为0.979% 至1.149%, 与草苁蓉的遗传距离为1.066% 至1.224%。研究结果表明psbA-trnH基因间区可以作为条形码来鉴定肉苁蓉及其混淆品。

Identification of Cistanche species (Orobanchaceae) based on sequences of the plastid psbA-trnH intergenic region

The dried succulent stems of Cistanche (Cistanche deserticola Y. C. Ma and Cistanche tubulosa Wight.) are one of the most widely used components of traditional Chinese medicines.  However, it is often confused and substituted with the roots of Orobanche pycnostachya, Boschniakia rossica (Cham. & Schltdl.) Standl., Cistanche sinensis Beck, and Cistanche salsa (C. A. Mey.) Beck.  In this study, we identified psbA-trnH regions from species and tested their suitable for the identification of the above mentioned taxa.  The psbA-trnH sequences showed considerable variations between species and thus were revealed as a promising candidate for barcoding of Cistanche species.  Additionally, the average genetic distance of psbA-trnH ranging from 0.077% to 0.743%.  In contrast, the intra-specific variation among Cistanche species was found to be  significantly different from those of other species, with percentages of variation studied ranged from 0% to 0.007%.  The sequence difference between the psbA-trnH sequences of Cistanche species and Orobanche pycnostachya ranged from 0.979% to 1.149%.  The distance between the Cistanche species and Boschniakia rossica ranged from 1.066% to 1.224%.  Our results suggest that the psbA-trnH intergenic spacer region represent a barcode that can be used to identify Cistanche species and other morphologically undistinguishable species.