Marechal L, Runeberg-Roos P, Grienenberger J M, Colin J, Weil J H, Lejeune B, Quetier F, Lonsdale D M
Institut de Biologie Moléculaire et Cellulaire, Université Louis Pasteur, Strasbourg, France.
Curr Genet. 1987;12(2):91-8. doi: 10.1007/BF00434662.
We have used bean mitochondrial (mt) and chloroplast (cp) tRNA(Trp) as probes to locate the corresponding genes on the mt and cp genomes of wheat and we have determined the nucleotide sequences of the wheat mt and cp tRNA(Trp) genes and of the flanking regions. Sequence comparisons show that the wheat mt and cp tRNA(Trp) genes are 97% homologous. On the wheat cp DNA, a tRNA(UGGPro) gene was found 139 bp upstream of the cp tRNA(Trp) gene. On the wheat mt DNA, a sequence of 23 nucleotides completely homologous with the 3' end of this cp tRNA(Pro) gene was found 136 bp upstream of the mt tRNA(Trp) gene, but there is only 38% homology between cp and mt wheat genomes in the intergenic regions. The overall organization of this region in the chloroplast genome (a tRNA(Trp) gene separated by about 140 bp from a tRNA(Pro) gene) is also found in the mitochondrial genome, suggesting that this mitochondrial fragment might have originated from a chloroplast DNA insertion. A comparison of the genes and of the intergenic regions located between the tRNA(Trp) gene and the tRNA(Pro) (or partial tRNA(Pro)) gene shows that there is an almost complete conservation of these sequences in the mitochondrial DNA of wheat and maize, whereas wheat mt and cp intergenic regions show more sequence divergence. Wheat mt tRNA(Trp) gene is encoded by the main mt genome (accounted for by the master chromosome) but, in the case of maize mitochondria, this gene was found to be encoded by the 2.3 kb linear plasmid, indicating that this plasmid is not dispensable in maize mitochondria.
我们使用菜豆线粒体（mt）和叶绿体（cp）的色氨酸转运RNA（tRNA(Trp)）作为探针，来定位小麦mt和cp基因组上的相应基因，并测定了小麦mt和cp的tRNA(Trp)基因及其侧翼区域的核苷酸序列。序列比较表明，小麦mt和cp的tRNA(Trp)基因具有97%的同源性。在小麦cp DNA上，发现一个tRNA(UGGPro)基因位于cp tRNA(Trp)基因上游139 bp处。在小麦mt DNA上，发现一段23个核苷酸的序列，与该cp tRNA(Pro)基因的3'端完全同源，位于mt tRNA(Trp)基因上游136 bp处，但在基因间隔区，小麦cp和mt基因组之间只有38%的同源性。叶绿体基因组中该区域的整体结构（一个tRNA(Trp)基因与一个tRNA(Pro)基因相隔约140 bp）在线粒体基因组中也有发现，这表明该线粒体片段可能起源于叶绿体DNA的插入。对位于tRNA(Trp)基因和tRNA(Pro)（或部分tRNA(Pro)）基因之间的基因和基因间隔区进行比较，结果表明，小麦和玉米线粒体DNA中的这些序列几乎完全保守，而小麦mt和cp的基因间隔区则表现出更多的序列差异。小麦mt tRNA(Trp)基因由主要的mt基因组（由主染色体负责）编码，但在玉米线粒体中，该基因由2.3 kb的线性质粒编码，这表明该质粒在玉米线粒体中并非可有可无。
