Handa Hirokazu
Laboratory of Plant Genecology, National Agricultural Research Center for Hokkaido Region, Sapporo 062-8555, Japan.
Nucleic Acids Res. 2003 Oct 15;31(20):5907-16. doi: 10.1093/nar/gkg795.
The entire mitochondrial genome of rapeseed (Brassica napus L.) was sequenced and compared with that of Arabidopsis thaliana. The 221 853 bp genome contains 34 protein-coding genes, three rRNA genes and 17 tRNA genes. This gene content is almost identical to that of Arabidopsis: However the rps14 gene, which is a pseudo-gene in Arabidopsis, is intact in rapeseed. On the other hand, five tRNA genes are missing in rapeseed compared to Arabidopsis, although the set of mitochondrially encoded tRNA species is identical in the two Cruciferae. RNA editing events were systematically investigated on the basis of the sequence of the rapeseed mitochondrial genome. A total of 427 C to U conversions were identified in ORFs, which is nearly identical to the number in Arabidopsis (441 sites). The gene sequences and intron structures are mostly conserved (more than 99% similarity for protein-coding regions); however, only 358 editing sites (83% of total editings) are shared by rapeseed and Arabidopsis: Non-coding regions are mostly divergent between the two plants. One-third (about 78.7 kb) and two-thirds (about 223.8 kb) of the rapeseed and Arabidopsis mitochondrial genomes, respectively, cannot be aligned with each other and most of these regions do not show any homology to sequences registered in the DNA databases. The results of the comparative analysis between the rapeseed and Arabidopsis mitochondrial genomes suggest that higher plant mitochondria are extremely conservative with respect to coding sequences and somewhat conservative with respect to RNA editing, but that non-coding parts of plant mitochondrial DNA are extraordinarily dynamic with respect to structural changes, sequence acquisition and/or sequence loss.
对油菜（甘蓝型油菜）的整个线粒体基因组进行了测序，并与拟南芥的线粒体基因组进行了比较。该基因组全长221853 bp，包含34个蛋白质编码基因、3个rRNA基因和17个tRNA基因。这种基因组成与拟南芥几乎相同：然而，在拟南芥中为假基因的rps14基因在油菜中却是完整的。另一方面，与拟南芥相比，油菜中缺少5个tRNA基因，尽管这两个十字花科植物中线粒体编码的tRNA种类是相同的。基于油菜线粒体基因组序列，系统地研究了RNA编辑事件。在开放阅读框中总共鉴定出427个C到U的转换，这与拟南芥中的数量（441个位点）几乎相同。基因序列和内含子结构大多是保守的（蛋白质编码区域的相似度超过99%）；然而，油菜和拟南芥仅共享358个编辑位点（占总编辑数的83%）：这两种植物的非编码区域大多是不同的。油菜和拟南芥线粒体基因组的比较分析结果表明，高等植物线粒体在编码序列方面极其保守，在RNA编辑方面 somewhat conservative（原文此处表述有误，推测可能是“ somewhat conservative”，意为“有点保守”），但植物线粒体DNA的非编码部分在结构变化、序列获得和/或序列丢失方面非常动态。
