Identification of species and materia medica withinSaussureasubg.Amphilaenabased on DNA barcodes

Abstract

Saussureais one of the most species-rich genera in the family Asteraceae, where some have a complex evolutionary history, including radiation and convergent evolution, and the identification of these species is notoriously difficult. This genus contains many plants with medical uses, and thus an objective identification method is urgently needed.Saussureasubg.Amphilaenais one of the four subgenera ofSaussureaand it is particularly rich in medical resources, where 15/39 species are used in medicine. To test the application of DNA barcodes in this subgenus, five candidates were sequenced and analyzed using 131 individuals representing 15 medical plants and four additional species from this subgenus. Our results suggested that internal transcribed spacer (ITS) +rbcL or ITS +rbcL +psbA-trnH could distinguish all of the species, while the ITS alone could identify all of the 15 medical plants. However, the species identification rates based on plastid barcodes were low, i.e., 0% to 36% when analyzed individually, and 63% when all four loci were combined. Thus, we recommend using ITS +rbcL as the DNA barcode forS.subg.Amphilaenaor the ITS alone for medical plants. Possible taxonomic problems and substitutes for medicinal plant materials are also discussed.