中国秋海棠属(秋海棠科)植物的DNA条形码评价

Evaluating Candidate DNA Barcodes among Chinese Begonia( Begoniaceae) Species

秋海棠属植物种类繁多,形态变异多样,导致种类的系统放置混乱,近缘种类鉴定困难。利用DNA条形码实现物种快速准确的鉴定技术具有不受形态特征约束的优势,为秋海棠属植物的分类鉴定提供了新的方法。本研究选择4个DNA条形码候选片段(rbcL,matK,trnH-psbA,ITS)对中国秋海棠属26种136个个体进行了分析。结果显示:叶绿体基因rbcL,matK和trnH-psbA种内和种间变异小,对秋海棠属植物的鉴别能力有限;ITS/ITS2种内和种间变异大,在本研究中物种正确鉴定率达到100%/96%,可考虑作为秋海棠属DNA条形码鉴定的候选片段。研究结果支持中国植物条形码研究组建议将核基因ITS/ITS2纳入种子植物DNA条形码核心片段中的观点。

Begonia is the biggest genus in the Begoniaceae and exhibits high morphological and ecological diversity, making intrageneric classification and species delimitation difficult, especially in the case of closely related species. In this respect, DNA barcoding has the advantage of achieving rapid species identification without relying on mor- phological characteristics, once a database containing species-specific sequences is established. In this study, we tested four candidate plant barcoding regions, including three chloroplast loci （ rbcL, matK, trnH-psbA） and one nuclear locus （ ITS）, in 136 samples representing 26 species of Begonia. The results demonstrated that species i- dentification based on rbcL, matK and trnH-psbA sequences was poor due to low interspecific variation. Conversely, ITS/ITS2 sequences showed significant intra- and interspecific divergence enabling a high level of species discrimi- nation （96%-100% ）. Consequently, ITS/ITS2 could be considered as a potential bircode for identifying Begonia species, which supports the proposal by the China Plant BOL Group that ITS/ITS2 should be incorporated into the core barcode for seed plants.