Data from: 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. Therefore, matK and rbcL should not be used as DNA barcode for species identification of Parnassia. Based on the overall performance, the combination of ITS + trnH-psbA, is proposed as the most suitable DNA barcode for identifying Parnassia species. DNA barcoding is a useful technique to providing a reliable and effective mean for the discrimination of Parnassia species, and in combination with morphology based taxonomy can be a robust approach for tackling taxonomically complex groups. In the light of our findings, we found among the three species not identified a possible cryptic speciation event in Parnassia.

DNA条形码（DNA barcoding）是一项借助标准化DNA序列实现物种鉴定的技术。本研究共采集了代表30个梅花草属（Parnassia）物种的105份样本，以测试4种候选DNA条形码（rbcL、matK、trnH-psbA及ITS）用于物种鉴定的有效性。研究结果显示，4种候选DNA标记均具备最高水平的引物通用性与测序成功率。作为单条DNA标记时，ITS区域的物种分辨率最高，达86.7%，其次为trnH-psbA，分辨率为73.3%。在所有多标记组合中，核心条形码组合matK + rbcL的物种鉴定成功率最低（63.3%），并不适用于梅花草属的DNA条形码鉴定。ITS + trnH-psbA组合的物种分辨能力最高，分辨率达90.0%（30个采样物种中的27个），与四标记组合的分辨能力相当；而ITS分别与matK、rbcL或matK + rbcL组合时，并未提升物种分辨能力。因此，matK与rbcL不适用于梅花草属的物种鉴定DNA条形码。综合各项性能表现，建议将ITS + trnH-psbA组合作为鉴定梅花草属物种的最优DNA条形码。DNA条形码技术可为梅花草属物种的分辨提供可靠且高效的手段，与基于形态学的分类学方法相结合，可成为解决分类学复杂类群问题的可靠方案。基于本研究结果，我们在3个未成功鉴定的物种中发现了梅花草属可能存在的隐种形成事件。