Bowers John E, Chapman Brad A, Rong Junkang, Paterson Andrew H
Plant Genome Mapping Laboratory, University of Georgia, Athens, Georgia 30602, USA.
Nature. 2003 Mar 27;422(6930):433-8. doi: 10.1038/nature01521.
Conservation of gene order in vertebrates is evident after hundreds of millions of years of divergence, but comparisons of the Arabidopsis thaliana sequence to partial gene orders of other angiosperms (flowering plants) sharing common ancestry approximately 170-235 million years ago yield conflicting results. This difference may be largely due to the propensity of angiosperms to undergo chromosomal duplication ('polyploidization') and subsequent gene loss ('diploidization'); these evolutionary mechanisms have profound consequences for comparative biology. Here we integrate a phylogenetic approach (relating chromosomal duplications to the tree of life) with a genomic approach (mitigating information lost to diploidization) to show that a genome-wide duplication post-dates the divergence of Arabidopsis from most dicots. We also show that an inferred ancestral gene order for Arabidopsis reveals more synteny with other dicots (exemplified by cotton), and that additional, more ancient duplication events affect more distant taxonomic comparisons. By using partial sequence data for many diverse taxa to better relate the evolutionary history of completely sequenced genomes to the tree of life, we foster comparative approaches to the study of genome organization, consequences of polyploidy, and the molecular basis of quantitative traits.
经过数亿年的分化，脊椎动物基因顺序的保守性十分明显，但将拟南芥序列与其他大约在1.7亿至2.35亿年前拥有共同祖先的被子植物（开花植物）的部分基因顺序进行比较，却得出了相互矛盾的结果。这种差异可能主要是由于被子植物倾向于发生染色体复制（“多倍体化”）以及随后的基因丢失（“二倍体化”）；这些进化机制对比较生物学有着深远的影响。在这里，我们将系统发育方法（将染色体复制与生命之树联系起来）与基因组方法（减少因二倍体化而丢失的信息）相结合，以表明全基因组复制发生在拟南芥与大多数双子叶植物分化之后。我们还表明，推断出的拟南芥祖先基因顺序与其他双子叶植物（以棉花为例）具有更多的共线性，并且额外的、更古老的复制事件影响着更远缘的分类比较。通过使用许多不同分类群的部分序列数据，以便更好地将完全测序基因组的进化历史与生命之树联系起来，我们促进了对基因组组织、多倍体后果以及数量性状分子基础的比较研究方法。
