Zhao X, Kochert G
Department of Botany, University of Georgia, Athens 30605.
Genome. 1993 Oct;36(5):944-53. doi: 10.1139/g93-124.
We have characterized a repeated DNA sequence (RTL122) from rice (Oryza sativa L.) with respect to its organization in the rice genome and its distribution among rice and other plants. The results indicate that the RTL122 sequence is interspersed in the rice genome and limited to the genus Oryza. It is highly polymorphic and can be used to fingerprint rice varieties. A structure was observed in which several repeated sequences were clustered in DNA regions of 15-20 kb. We characterized three bacteriophage lambda clones that contained the RTL122 sequence. Southern analysis using probes derived from restriction fragments of the three lambda clones indicated that all fragments except one are interspersed repeated sequences and belong to different repeated sequence families. Subsequent slot blot hybridization showed that most of them are only present within the genus Oryza. Some of the Oryza-specific, physically linked sequences show the same phylogenetic distribution, which suggests that these sequences might have evolved in a coordinate fashion. On the other hand, some of the repeated sequences have a different distribution even though they are physically adjacent in the genome. We speculate that such blocks of interspersed repeated sequences may serve as hotspots for rapid changes in the rice genome.
我们已对来自水稻（Oryza sativa L.）的一个重复DNA序列（RTL122）在水稻基因组中的组织形式及其在水稻和其他植物中的分布进行了表征。结果表明，RTL122序列散布于水稻基因组中，且仅限于稻属。它具有高度多态性，可用于水稻品种的指纹识别。观察到一种结构，其中几个重复序列聚集在15 - 20 kb的DNA区域。我们对三个包含RTL122序列的噬菌体λ克隆进行了表征。使用源自这三个λ克隆限制性片段的探针进行的Southern分析表明，除一个片段外，所有片段都是散布的重复序列，且属于不同的重复序列家族。随后的狭缝杂交显示，它们中的大多数仅存在于稻属内。一些水稻特有的、物理上相连的序列显示出相同的系统发育分布，这表明这些序列可能是以协同方式进化的。另一方面，一些重复序列尽管在基因组中物理上相邻，但分布却不同。我们推测，这种散布的重复序列块可能是水稻基因组快速变化的热点。
