Duplicated genes evolve independently after polyploid formation in cotton
Duplicated genes evolve independently after polyploid formation in cotton
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DOI：
10.1073/pnas.96.25.14406
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发表时间：
1999-12-07
影响因子：
11.1
通讯作者：
Wendel, JF
中科院分区：
文献类型：
--
作者：
Cronn, RC;Small, RL;Wendel, JF
在产生基因复制的许多过程中，多倍性是独特的，因为整个基因组都是复制的。这一过程在许多真核生物的进化中非常重要，在植物中也经常发生。最近的证据表明，多倍化可能伴随着快速的基因组变化，但最近加倍的多倍化（同源）的离散位点的进化命运还没有研究。在这里，我们使用基因座特异性分离技术与比较映射的特点同源同源基因座在异源多倍体棉花（陆地棉）和代表其二倍体祖先的物种的演变。我们从异源多倍体的两个基因组、两个祖先二倍体基因组和适当的外群中分离并测序了16个位点。系统发育分析所得到的73.5 kb的序列数据表明，对于16个位点（14.7 kb/基因组），从生物体的历史预期的拓扑结构被恢复。与棉花中重复DNA的观察相反，在异源多倍体中没有重复基因之间相互作用的证据。多倍体并不伴随着一个明显的增加，突变指示假基因形成。此外，同源同源多倍体和直向同源二倍体之间的分歧率的差异是难以区分的基因座，与显着的率偏差仅限于两个假定的假基因。我们的研究结果表明，异源多倍体棉花中大多数重复基因的进化彼此独立，并以相同的速度为他们的二倍体祖先。这些基因停滞伴随多倍体化的迹象提供了一个鲜明的对比，最近的例子，在异源多倍体基因组的快速进化。
Of the many processes that generate gene duplications, polyploidy is unique in that entire genomes are duplicated. This process has been important in the evolution of many eukaryotic groups, and it occurs with high frequency in plants. Recent evidence suggests that polyploidization may be accompanied by rapid genomic, changes, but the evolutionary fate of discrete loci recently doubled by polyploidy (homoeologues) has not been studied. Here we use locus-specific isolation techniques with comparative mapping to characterize the evolution of homoeologous loci in allopolyploid cotton (Gossypium hirsutum) and in species representing its diploid progenitors. We isolated and sequenced 16 loci from both genomes of the allopolyploid, from both progenitor diploid genomes and appropriate outgroups. Phylogenetic analysis of the resulting 73.5 kb of sequence data demonstrated that for an 16 loci (14.7 kb/genome), the topology expected from organismal history was recovered. In contrast to observations Involving repetitive DNAs in cotton, there was no evidence of interaction among duplicated genes in the allopolyploid. Polyploidy was not accompanied by an obvious increase in mutations indicative of pseudogene formation. Additionally, differences in rates of divergence among homoeologues in polyploids and orthologues in diploids were indistinguishable across loci, with significant rate deviation restricted to two putative pseudogenes. Our results indicate that most duplicated genes in allopolyploid cotton evolve independently of each other and at the same rate as those of their diploid progenitors. These indications of genic stasis accompanying polyploidization provide a sharp contrast to recent examples of rapid genomic evolution in allopolyploids.