ACCELERATED EVOLUTION OF PLANT MITOCHONDRIAL DNA

植物线粒体 DNA 的加速进化

• 批准号: 2518871
• 负责人: CHRISTOPHER L PARKINSON
• 金额: $ 2.62万
• 依托单位: TRUSTEES OF INDIANA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-27 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/2518871
• 关键词: biochemical evolution; introns; mitochondrial DNA; molecular genetics; plant genetics; plant proteins; posttranscriptional RNA processing

Mitochondrial genomes have undergone massive reductions in size and gene content since their endosymbiotic origin. Furthermore, compared with the genomes of their bacterial ancestors, most mitochondrial DNA lineages evolve rapidly in sequence. Land plants are apparently the one exception to this, but we have very recently identified two independent lineages of plants (Pelargonium and Plantago) whose substitution rates for four mitochondrial protein and two rRNA genes are at least 5-30 times higher than those of typical, slowly-evolving plant mitochondrial genomes. Hypotheses for the mechanisms underlying these major and recent increases in mitochondrial DNA mutation rate include: 1) deficient DNA repair, 2) error-prone DNA replication, and 3) error-prone retroprocessing. Although virtually all plant mitochondrial mRNAs are subject to extensive RNA editing, our data indicate that mitochondrial RNA editing does not occur in either Pelargonium or Plantago, that in fact their genomes are already edited as a consequence of unusually extensive retroprocessing. These data support the hypothesis of intense, error-prone retroprocessing, i.e., mutagenic reverse transcription followed by recombination back into the genome. Experiments are proposed to test among the various hypotheses and to determine the mechanisms responsible for the observed acceleration in mitochondrial DNA evolution in Pelargonium and Plantago.

线粒体基因组的大小和基因都发生了巨大的减少 自其内共生起源以来的含量。 此外，与 其细菌祖先的基因组，大多数线粒体 DNA 谱系按顺序快速演化。 陆地植物显然是其中之一 例外，但我们最近发现了两个独立的 植物谱系（天竺葵和车前草）的替代率 四个线粒体蛋白和两个 rRNA 基因至少为 5-30 比典型的、缓慢进化的植物线粒体高出几倍 基因组。 对这些主要和潜在机制的假设 最近线粒体 DNA 突变率的增加包括：1) DNA 修复缺陷，2) DNA 复制容易出错，3) 容易出错 后处理。 尽管几乎所有植物线粒体 mRNA 都是 经过广泛的 RNA 编辑，我们的数据表明线粒体 RNA 编辑不会在天竺葵或车前草中发生， 事实上，由于不寻常的原因，他们的基因组已经被编辑过 广泛的后处理。 这些数据支持以下假设 强烈的、容易出错的逆处理，即诱变逆转 转录后重组回基因组。 提出实验来测试各种假设并 确定导致观察到的加速的机制 天竺葵和车前子的线粒体 DNA 进化。