Insights into the Evolution of Mitochondrial Genome Size from Complete Sequences of Citrullus lanatus and Cucurbita pepo (Cucurbitaceae)
Insights into the Evolution of Mitochondrial Genome Size from Complete Sequences of Citrullus lanatus and Cucurbita pepo (Cucurbitaceae)
复制标题
DOI：
10.1093/molbev/msq029
复制
发表时间：
2010-06-01
影响因子：
10.7
通讯作者：
Palmer, Jeffrey D.
中科院分区：
文献类型：
--
作者：
Alverson, Andrew J.;Wei, XiaoXin;Palmer, Jeffrey D.
种子植物的线粒体基因组异常大，大小至少相差一个数量级。这种变异大多发生在一个单一的科，葫芦科，其基因组的大小估计在390到2900 kb之间。我们测序了瓜类（西瓜：379,236 nt）和瓜类（西葫芦：982,833 nt）两个最小的线粒体基因组，并确定了它们的RNA编辑含量。相对紧凑的瓜类线粒体基因组实际上包含更多更长的基因和内含子，更长的片段复制，以及更明显的核源DNA。Cucurbita线粒体基因组的大尺寸反映了叶绿体序列（> 113 kb）和短重复序列（> 370 kb）的空前积累。低突变率被认为是植物线粒体基因组大小和RNA编辑频率增加的基础。然而，尽管其基因组大得多，Cucurbita的同义替换率（可能是突变率）明显高于Citrullus，但RNA编辑水平相当。在葫芦科中，突变率、基因组大小和RNA编辑的进化明显解耦，要么反映了简单的随机变异，要么反映了不同因素的治理。
The mitochondrial genomes of seed plants are unusually large and vary in size by at least an order of magnitude. Much of this variation occurs within a single family, the Cucurbitaceae, whose genomes range from an estimated 390 to 2,900 kb in size. We sequenced the mitochondrial genomes of Citrullus lanatus (watermelon: 379,236 nt) and Cucurbita pepo (zucchini: 982,833 nt)-the two smallest characterized cucurbit mitochondrial genomes-and determined their RNA editing content. The relatively compact Citrullus mitochondrial genome actually contains more and longer genes and introns, longer segmental duplications, and more discernibly nuclear-derived DNA. The large size of the Cucurbita mitochondrial genome reflects the accumulation of unprecedented amounts of both chloroplast sequences (> 113 kb) and short repeated sequences (> 370 kb). A low mutation rate has been hypothesized to underlie increases in both genome size and RNA editing frequency in plant mitochondria. However, despite its much larger genome, Cucurbita has a significantly higher synonymous substitution rate (and presumably mutation rate) than Citrullus but comparable levels of RNA editing. The evolution of mutation rate, genome size, and RNA editing are apparently decoupled in Cucurbitaceae, reflecting either simple stochastic variation or governance by different factors.