Phylogenetic utility of the external transcribed spacer (ETS) of 18S-26S rDNA:: Congruence of ETS and ITS trees of Calycadenia (Compositae)
Phylogenetic utility of the external transcribed spacer (ETS) of 18S-26S rDNA:: Congruence of ETS and ITS trees of Calycadenia (Compositae)
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DOI：
10.1006/mpev.1998.0545
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发表时间：
1998-12-01
影响因子：
4.1
通讯作者：
Markos, S
中科院分区：
文献类型：
--
作者：
Baldwin, BG;Markos, S
测定了19个Calycadenia/Osmadenia属植物和2个外类群菊科植物的18 S-26 S核核糖体DNA外转录间隔区（ETS）3'端序列，并与rDNA内转录间隔区（ITS）数据进行比较，以评估ETS 3'端序列在重建植物遗传学中的应用价值。根据植物、真菌和动物基因组序列设计通用引物扩增基因间间隔区（IGS），并构建被子植物引物对向日葵族（Heliantheae）成员ETS的3'端进行测序。基于这些序列，设计了一个在Heliantheae sensu late中有用的内部ETS引物，以直接扩增和测序研究分类群中的3' ETS区域，这是基于ITS序列的早期系统发育研究的对象。扩增的ETS区域的大小变化从大约350到700 bp不等，部分归因于大约200 bp的串联重复在一个共同的祖先Calycadenia/Osmadenia的向日葵属的分类群。系统发育分析的200 bp的亚重复序列和检查的apomorphic重复区域的变化表明，在Calycadenia/Osmadenia的亚重复序列已经发展分歧-整个扩增ETS区域的系统发育分析产生了一个高度解析的严格的共识树，几乎是相同的拓扑结构的ITS树，具有强大的引导和衰减的支持，在大多数分支。结合ETS和ITS数据的简约分析产生了一个严格的共识树，更好地解决和一般更好地支持比树的基础上，无论是数据集分别分析。我们计算出在ETS区域中核苷酸取代的序列进化速率比ITS-1 + ITS-2高约1.3至2.4倍。在内组中观察到变量（1.3 ETS：1 ITS）和潜在信息（1.5 ETS：1 ITS）位点比例的相似差异。ETS和ITS数据的同质性水平相似。我们的结论是，ETS持有很大的希望，增加ITS数据的系统发育研究的年轻血统。(C)北京：科学出版社.
The 3' region of the external transcribed spacer (ETS) of 18S-26S nuclear ribosomal DNA was sequenced in 19 representatives of Calycadenia/Osmadenia and two outgroup species (Compositae) to assess its utility for phylogeny reconstruction compared to rDNA internal transcribed spacer (ITS) data. Universal primers based on plant, fungal, and animal sequences were designed to amplify the intergenic spacer (IGS) and an angiosperm primer was constructed to sequence the 3' end of the ETS in members of tribe Heliantheae. Based on these sequences, an internal ETS primer useful across Heliantheae sensu late was designed to amplify and sequence directly the 3' ETS region in the study taxa, which were the subjects of an earlier phylogenetic investigation based on ITS sequences. Size variation in the amplified ETS region varied across taxa of Heliantheae sensu late from approximately 350 to 700 bp, in part attributable to an approximately 200-bp tandem duplication in a common ancestor of Calycadenia/Osmadenia. Phylogenetic analysis of the 200-bp subrepeats and examination of apomorphic changes in the duplicated region demonstrate that the subrepeats in Calycadenia/Osmadenia have evolved divergently Phylogenetic analyses of the entire amplified ETS region yielded a highly resolved strict consensus tree that is nearly identical in topology to the ITS tree, with strong bootstrap and decay support on most branches. Parsimony analyses of combined ETS and ITS data yielded a strict consensus tree that is better resolved and generally better supported than trees based on either data set analyzed separately. We calculated an approximately 1.3- to 2.4-fold higher rate of sequence evolution by nucleotide substitution in the ETS region studied than in ITS-1 + ITS-2. A similar disparity in the proportion of variable (1.3 ETS:1ITS) and potentially informative (1.5 ETS:1 ITS) sites was observed for the ingroup. Levels of homoplasy are similar in the ETS and ITS data. We conclude that the ETS holds great promise for augmenting ITS data for phylogenetic studies of young lineages. (C) 1998 Academic Press.