Department of Biology, Indiana University, Bloomington, Indiana, United States of America.
PLoS One. 2011 Jan 20;6(1):e16404. doi: 10.1371/journal.pone.0016404.
The mitochondrial genomes of seed plants are exceptionally fluid in size, structure, and sequence content, with the accumulation and activity of repetitive sequences underlying much of this variation. We report the first fully sequenced mitochondrial genome of a legume, Vigna radiata (mung bean), and show that despite its unexceptional size (401,262 nt), the genome is unusually depauperate in repetitive DNA and "promiscuous" sequences from the chloroplast and nuclear genomes. Although Vigna lacks the large, recombinationally active repeats typical of most other seed plants, a PCR survey of its modest repertoire of short (38-297 nt) repeats nevertheless revealed evidence for recombination across all of them. A set of novel control assays showed, however, that these results could instead reflect, in part or entirely, artifacts of PCR-mediated recombination. Consequently, we recommend that other methods, especially high-depth genome sequencing, be used instead of PCR to infer patterns of plant mitochondrial recombination. The average-sized but repeat- and feature-poor mitochondrial genome of Vigna makes it ever more difficult to generalize about the factors shaping the size and sequence content of plant mitochondrial genomes.
植物的线粒体基因组在大小、结构和序列内容上都非常不稳定，重复序列的积累和活性是这种变异的主要原因。我们报告了首例完全测序的豆科植物绿豆（Vigna radiata）的线粒体基因组，并表明尽管其大小（401262nt）并不特殊，但该基因组中重复 DNA 和来自叶绿体及核基因组的“混杂”序列却异常匮乏。尽管 Vigna 缺乏大多数其他种子植物中典型的大型、重组活跃的重复序列，但对其适度的短重复序列（38-297nt）的 PCR 调查仍显示出所有这些重复序列都存在重组的证据。然而，一组新的对照实验表明，这些结果可能部分或全部反映了 PCR 介导的重组的假象。因此，我们建议使用其他方法，特别是高通量基因组测序，来代替 PCR 以推断植物线粒体重组的模式。Vigna 中等大小但重复序列和特征匮乏的线粒体基因组使得我们更难以概括影响植物线粒体基因组大小和序列内容的因素。
