Applying plant DNA barcodes to identify species of Parnassia (Parnassiaceae)

DNA barcoding is a technique to identity species by using standardized DNA sequences. In the present study, a total of 105 samples, representing 30 Parnassia species were collected to test the effectiveness of four proposed DNA barcodes (rbcL, matK, trnH-psbA and ITS) for species identification. Our results demonstrated that all four candidate DNA markers have a maximum level of primer universality and sequencing success. As single DNA marker, ITS region provided the highest species resolution with 86.7%, followed by trnH-psbA with 73.3%. The combination of the core barcode, matK + rbcL, gave the lowest species identification success (63.3%) among any combination of multiple markers, and was found unsuitable as DNA barcode for Parnassia. The combination of ITS + trnH-psbA achieved the highest species discrimination with 90.0% resolution (27 out of 30 sampled species), equal to the four-marker combination; ITS combined with matK, rbcL or matK + rbcL did not improve species discrimination...