Watanabe N, Nakazono M, Kanno A, Tsutsumi N, Hirai A
Laboratory of Radiation Genetics, Faculty of Agriculture, University of Tokyo, Japan.
Curr Genet. 1994 Nov-Dec;26(5-6):512-8. doi: 10.1007/BF00309942.
The transfer of fragments of DNA from chloroplast genomes to mitochondrial genomes is considered to be a general phenomenon in higher plants. In the present study, Southern hybridization, together with amplification by PCR and DNA sequencing techniques, was used to examine the regions homologous to chloroplast rps19 in the mitochondrial genomes of several gramineous plants. In all the mitochondrial DNAs from the gramineous plants examined, except for that from wheat, the transferred fragments of chloroplast DNA were found to be maintained and the same junctions of mitochondrion-specific and chloroplast-like sequences were found at one terminus. This finding indicates that the transfer of the chloroplast sequence occurred in the distant past during the evolution of gramineous plants. Subsequent analysis revealed that the fragments had been variously rearranged among species with respect to the other terminus. Considering the current diversity of this one particular transferred fragment of chloroplast DNA, we propose that chloroplast-derived DNA sequences that have lost their original functions tend to be rearranged during evolution in mitochondrial genomes.
DNA片段从叶绿体基因组转移至线粒体基因组被认为是高等植物中的普遍现象。在本研究中，Southern杂交结合PCR扩增和DNA测序技术，用于检测几种禾本科植物线粒体基因组中与叶绿体rps19同源的区域。在所检测的禾本科植物的所有线粒体DNA中，除了小麦的线粒体DNA外，均发现叶绿体DNA的转移片段得以保留，并且在一端发现了相同的线粒体特异性序列与类叶绿体序列的连接。这一发现表明，叶绿体序列的转移发生在禾本科植物进化的远古时期。随后的分析表明，这些片段在物种间的另一端发生了不同程度的重排。考虑到这一特定叶绿体DNA转移片段目前的多样性，我们提出，失去原有功能的叶绿体衍生DNA序列在进化过程中往往会在线粒体基因组中发生重排。
