Origins and Recombination of the Bacterial-Sized Multichromosomal Mitochondrial Genome of Cucumber
Origins and Recombination of the Bacterial-Sized Multichromosomal Mitochondrial Genome of Cucumber
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DOI：
10.1105/tpc.111.087189
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发表时间：
2011-07-01
期刊：
影响因子：
11.6
通讯作者：
Palmer, Jeffrey D.
中科院分区：
文献类型：
--
作者：
Alverson, Andrew J.;Rice, Danny W.;Palmer, Jeffrey D.
葫芦科的开花植物的成员拥有已知最大的线粒体基因组。在这里，我们报告的1685 kb的黄瓜（黄瓜）线粒体基因组。我们帮助解决了一个30年的谜团，其大尺寸的起源，表明它主要反映了分散的重复序列的增殖，现有内含子的扩展，以及从不同来源，包括黄瓜核和叶绿体基因组，病毒和细菌的序列的收购。黄瓜基因组具有植物线粒体的新结构，映射为三个完全或大部分自主的环状染色体（长度1556，84和45 kb），其相对丰度在两倍范围内变化。这些特性表明，三条染色体的复制是相互独立的。两条较小的染色体缺乏已知的功能基因，但仍然包含诊断线粒体特征。配对末端测序冲突揭示了染色体之间重组动力学的差异，为此开发了一个解释性模型，以及大量的低频基因组构象，其中许多可能是由于跨中等大小的，有时高度发散的重复序列的不对称重组。这些发现突出了基因组测序的承诺，阐明植物线粒体基因组的重组动力学。
Members of the flowering plant family Cucurbitaceae harbor the largest known mitochondrial genomes. Here, we report the 1685-kb mitochondrial genome of cucumber (Cucumis sativus). We help solve a 30-year mystery about the origins of its large size by showing that it mainly reflects the proliferation of dispersed repeats, expansions of existing introns, and the acquisition of sequences from diverse sources, including the cucumber nuclear and chloroplast genomes, viruses, and bacteria. The cucumber genome has a novel structure for plant mitochondria, mapping as three entirely or largely autonomous circular chromosomes (lengths 1556, 84, and 45 kb) that vary in relative abundance over a twofold range. These properties suggest that the three chromosomes replicate independently of one another. The two smaller chromosomes are devoid of known functional genes but nonetheless contain diagnostic mitochondrial features. Paired-end sequencing conflicts reveal differences in recombination dynamics among chromosomes, for which an explanatory model is developed, as well as a large pool of low-frequency genome conformations, many of which may result from asymmetric recombination across intermediate-sized and sometimes highly divergent repeats. These findings highlight the promise of genome sequencing for elucidating the recombinational dynamics of plant mitochondrial genomes.