Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
Genome Biol Evol. 2011;3:743-8. doi: 10.1093/gbe/evr068. Epub 2011 Jul 29.
Mitochondrial genomes often contain large amounts of plastid DNA (ptDNA)-derived sequences (MTPTs). It has been suggested that the intercompartmental transfer of ptDNA is greatly reduced in species with only a single plastid per cell (monoplastidic) as compared with those with many plastids per cell (polyplastidic). This hypothesis has not been applied to the movement of DNA from plastids to mitochondria. By analyzing the organelle genomes from diverse mono- and polyplastidic taxa, I show that MTPTs are restricted to the mitochondrial genomes of species with many plastids per cell and are absent from those with one plastid per cell or with monoplastidic meristematic systems. Moreover, the most bloated mitochondrial genomes that were explored had the largest MTPT contents. These data, like previous results on ptDNA-derived sequences in nuclear genomes, support the hypothesis that plastid number and the forces governing the expansion and contraction of noncoding mitochondrial DNA (mtDNA) influence MTPT abundance. I also show that plastid genomes are depauperate in mtDNA-derived sequences (PTMTs), irrespective of the number of mitochondria per cell and plastid genome size, which may reflect the lack of a DNA uptake system in plastids.
线粒体基因组通常含有大量的质体 DNA（ptDNA）衍生序列（MTPTs）。有人认为，与每个细胞具有多个质体（多质体）的物种相比，每个细胞只有一个质体（单质体）的物种中质体 DNA 的细胞间转移大大减少。这个假设尚未应用于 DNA 从质体到线粒体的运动。通过分析来自不同单质体和多质体分类群的细胞器基因组，我表明 MTPTs 仅限于每个细胞具有多个质体的物种的线粒体基因组，而不存在于每个细胞具有一个质体或具有单质体分生组织系统的物种中。此外，探索过的最膨胀的线粒体基因组具有最大的 MTPT 含量。这些数据，与核基因组中 ptDNA 衍生序列的先前结果一样，支持这样的假设，即质体数量和控制非编码线粒体 DNA（mtDNA）扩张和收缩的力量影响 MTPT 的丰度。我还表明，无论每个细胞的线粒体数量和质体基因组大小如何，质体基因组在 mtDNA 衍生序列（PTMTs）中都很匮乏，这可能反映了质体中缺乏 DNA 摄取系统。
