研究采用4种DNA序列,分析了各片段序列特征以及在串珠藻科植物中种属水平的鉴定能力,包括线粒体COI-5P、cox2-3 spacer序列,以及叶绿体rbcL、UPA序列.结果表明,COI-5P、cox2-3 spacer、UPA以及rb-cL序列的PCR扩增成功率分别为96%、100%、96%和98%.其中,COI-5P、cox2-3 spacer和UPA的片段大小符合标准DNA条形码的判定标准,即片段大小在300—800 bp,能够通过单对引物双向测序获得.系统发育分析的结果显示,这4种DNA片段在串珠藻属植物的鉴定中能够鉴定大部分的种类,但COI-5P、cox2-3 spacer以及rbcL序列均不能将两种中国特有种洪洞串珠藻B.hongdongense和长柄串珠藻B.longipedicellatum与弧形串珠藻B.arcuatum分开.在种水平的鉴定中,UPA基因的种间差异最大,显示了较好的分离效果,在串珠藻科植物的鉴定中可以作为一个标准的DNA条形码.%DNA barcoding refers to the application of a small number of DNA fragments to achieve reliable, automatable species-level identification. In this study, the suitability of four candidate sequence regions were assessed-mitochondrial COI-5P andcox2-3 spacer, plastidrbcL and UPA-for species delimitation and dis-crimination in family Batrachospermaceae. The percentage of successful PCR amplifications of COI-5P, cox2-3 spacer, UPA, andrbcL markers was 96%, 100%, 96%, and 98%, respectively. COI-5P, UPA, and cox2-3 spacer sequence lengths were amenable to the acquisition of bidirectional sequencing reads using single primer pairs and met our size criterion of 300—800 bp. Phylogenetic analyses revealed that all four se-quence regions were useful for species-level identification in the genus Batrachospermum except for some al-lied species. The two Chinese endemic speciesB. hongdongense andB. longipedicellatum were unable to dif-ferentiate fromB. arcuatum using COI-5P,cox2-3 spacer, andrbcL markers, excepted for the UPA region. For species-level identification, the UPA locus exhibited the highest interspecific distances. We therefore re-commended the plastid UPA gene as a standard DNA barcode in Batrachospermaceae, but acknowledge that there are no shared alleles between the endemic species.
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