Department of Biochemistry, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
EMBO J. 1984 Feb;3(2):297-302. doi: 10.1002/j.1460-2075.1984.tb01799.x.
Closely linked genes for 18S and 5S rRNAs have been located on four different cloned SalI restriction fragments of wheat (Triticum aestivum L.) mitochondrial DNA. Restriction analysis has revealed that in each of the cloned fragments, the 18S and 5S rRNA genes are contained within the same basic structural unit, R, which is at least 4 kbp long. This unit is flanked by sequences designated u (0.8 kbp), v (13.7 kbp), w (0.7 kbp), and y (1.4 kbp), in the orientations v-R-w, v-R-y, u-R-w, and u-R-y in the four different SalI fragments. We conclude that 18S + 5S rRNA genes are located at several distinct sites in the wheat mitochondrial genome, and suggest that reciprocal intra- and/or intermolecular recombination between such repeated sequences could promote extensive genomic rearrangement and thus contribute to the physical heterogeneity that is a hallmark of most plant mitochondrial DNAs.
18S 和 5S rRNA 紧密连锁的基因已被定位在小麦（Triticum aestivum L.）线粒体 DNA 的四个不同的克隆 SalI 限制片段上。限制分析表明，在每个克隆片段中，18S 和 5S rRNA 基因都包含在相同的基本结构单元 R 内，该单元至少长 4 kbp。该单元被侧翼序列 u（0.8 kbp）、v（13.7 kbp）、w（0.7 kbp）和 y（1.4 kbp）包围，在四个不同的 SalI 片段中，其方向为 v-R-w、v-R-y、u-R-w 和 u-R-y。我们得出结论，18S + 5S rRNA 基因位于小麦线粒体基因组的几个不同位置，并表明这种重复序列之间的相互和/或分子内重组可能促进广泛的基因组重排，从而导致大多数植物线粒体 DNA 的物理异质性成为其特征。
