海三棱藨草及其近缘种的DNA条形码研究

Study on × Bolboschoenoplectus mariqueter and its related species based on DNA barcoding

关键词:  海三棱藨草, 近缘种, DNA条形码, 物种鉴定, 亲缘关系

Key words:  Bolboschoenoplectus mariqueter, related species, DNA barcoding, species identification, genetic relationship

摘要:

海三棱藨草 [× Bolboschoenoplectus mariqueter(Tang & F. T. Wang)Tatanov]的分类学地位至今尚无定论。为明确海三棱藨草的分类学地位并探讨其与近缘种的关系,该研究分别利用1个核基因(ITS)和5个叶绿体基因(matK、ndhF、rbcL、trnL和trnL-trnF)的DNA条形码序列对海三棱藨草及其近缘种的4种21批样品进行扩增和测序,通过采用相似性搜索算法对单一序列和序列组合的物种鉴定效率进行评价,并基于贝叶斯推断方法构建系统发育树进行鉴定分析。结果表明:(1)ITS + matK序列组合的物种鉴定效率最高,为71.4%,可实现海三棱藨草及其近缘种的种间区分、鉴定。(2)基于ITS + matK序列组合构建海三棱藨草及其近缘种的系统发育树,发现同一物种的样品聚集度较好,海三棱藨草与三棱草属 [Bolboschoenus(Asch.)Palla]的物种聚为一支,明显与水葱属 [Schoenoplectus(Rchb.)Palla]物种分开,并且海三棱藨草与海滨三棱草 [Bolboschoenus maritimus(Linnaeus)Palla]形成单系。综上所述,ITS + matK序列组合可作为海三棱藨草及其近缘种物种鉴定的最佳条形码序列,研究结果不支持海三棱藨草为天然杂交种的观点,而应将其归入三棱草属中,海三棱藨草应为海滨三棱草的异名。该研究结果为海三棱藨草及其近缘种的分类学研究提供了分子依据。

Abstract:

The taxonomic status of × Bolboschoenoplectus mariqueter(Tang & F.T.Wang)Tatanov is still up for debate. To clarify this status and explore its genetic relationship with closely related species, the candidate DNA barcode sequences of one nuclear gene(ITS)and five chloroplast genes(matK, ndhF, rbcL, trnL and trnL-trnF)were used for PCR amplification and sequencing of 21 individuals from four species, including × Bolboschoenoplectus mariqueter and its related species. The basic local alignment search tool was then applied to evaluate the identification efficiency of the screened barcode sequences and sequence combinations. Finally, species identification analyses were performed by constructing a phylogenetic tree using the Bayesian inference method. The results were as follows:(1)The ITS + matK sequence combination showed the highest species-resolving degree of 71.4%, which could achieve interspecific differentiation and identification of × Bolboschoenoplectus mariqueter and its closely related species.(2)According to the phylogenetic tree based on ITS + matK sequence combination, samples of the same species showed better aggregation and were mostly monophyletic, with × Bolboschoenoplectus mariqueter clustered together with all Bolboschoenus(Asch.)Palla individuals, rather than Schoenoplectus(Rchb.)Palla species. All × Bolboschoenoplectus mariqueter and Bolboschoenus maritimus(Linnaeus)Palla samples formed a monophyletic clade. In conclusion, ITS + matK sequence combination appears to be the best barcode sequence for interspecific identification of × Bolboschoenoplectus mariqueter and its related species. Furthermore, × Bolboschoenoplectus mariqueter could be a synonym of Bolboschoenus maritimus rather than a natural hybrid. This study establishes a theoretical foundation for the taxonomic research on × Bolboschoenoplectus mariqueter and its closely related species.