Phylogeny of seed plants based on all three genomic compartments: Extant gymnosperms are monophyletic and Gnetales' closest relatives are conifers
Phylogeny of seed plants based on all three genomic compartments: Extant gymnosperms are monophyletic and Gnetales' closest relatives are conifers
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DOI：
10.1073/pnas.97.8.4092
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发表时间：
2000-04-11
影响因子：
11.1
通讯作者：
dePamphilis, CW
中科院分区：
文献类型：
--
作者：
Bowe, LM;Coat, G;dePamphilis, CW
努力解决达尔文的“可憎之谜”-被子植物的起源-导致的结论是买麻藤目和各种化石群是姐妹被子植物，形成“花植物。“然而，形态学上的同源性很难解释，分子数据也没有提供种子植物主要群体之间关系的清晰解析。我们介绍了两个序列数据集从缓慢演变的线粒体基因，cox 1和atpA，这毫不含糊地拒绝anthophyte假说，而不是买麻藤和针叶树之间的密切关系。吝啬和可能性为基础的分析质体rbcL和核18 S rDNA单独和cox 1和atpA也强烈支持买麻藤针叶树分组。令人惊讶的是，四个基因中的三个（除了核rDNA）和组合的三个基因组分析也表明或强烈支持买麻藤属作为松科的姐妹植物。分析与外群筛选，以避免长分支一致确定所有裸子植物作为一个单系姐妹群被子植物，结合三个和四个基因的根分析解决了分支顺序为其余的主要群体苏铁类从其他裸子植物分离第一，其次是银杏，然后（买麻藤+松科）姐妹与所有其他针叶树家庭的单系组。这种分子遗传学与目前对种子植物形态学的解释强烈冲突，并意味着买麻藤和被子植物之间的许多相似之处，如“花状”生殖结构和双受精，是独立产生的，而其他特征可能是作为一个扩展的针叶树群（包括买麻藤目）的突触形态出现的，最初的被子植物，裸子植物分裂意味着一个长干血统之前的爆炸性中生代辐射的显花植物，并建议被子植物的起源和同源性，应寻求灭绝的种子植物群。
Efforts to resolve Darwin's "abominable mystery"-the origin of angiosperms-have led to the conclusion that Gnetales and various fossil groups are sister to angiosperms, forming the "anthophytes." Morphological homologies, however, are difficult to interpret, and molecular data have not provided clear resolution of relationships among major groups of seed plants. We introduce two sequence data sets from slowly evolving mitochondrial genes, cox1 and atpA, which unambiguously reject the anthophyte hypothesis, favoring instead a close relationship between Gnetales and conifers. Parsimony- and likelihood-based analyses of plastid rbcL and nuclear 18S rDNA alone and with cox1 and atpA also strongly support a gnetophyte-conifer grouping. Surprisingly, three of four genes (all but nuclear rDNA) and combined three-genome analyses also suggest or strongly support Gnetales as derived conifers, sister to Pinaceae. Analyses with outgroups screened to avoid long branches consistently identify all gymnosperms as a monophyletic sister group to angiosperms, Combined three- and four-gene rooted analyses resolve the branching order for the remaining major groups-cycads separate from other gymnosperms first, followed by Ginkgo and then (Gnetales + Pinaceae) sister to a monophyletic group with all other conifer families. The molecular phylogeny strongly conflicts with current interpretations of seed plant morphology, and implies that many similarities between gnetophytes and angiosperms, such as "flower-like" reproductive structures and double fertilization, were independently derived, whereas other characters could emerge as synapomorphies for an expanded conifer group including Gnetales, An initial angiosperm-gymnosperm split implies a long stem lineage preceding the explosive Mesozoic radiation of flowering plants and suggests that angiosperm origins and homologies should be sought among extinct seed plant groups.