Segmental duplications on rice (Oryza sativa L.) chromosomes 8, 9, 11, and 12 were studied by examining the distributions of sequences resolved by 13 probes detecting multiple copies of DNA sequences. Four of the hybridization bands detected by a repetitive sequence probe, rTRS, were mapped to the ends of all the four chromosomes. Two or three of the bands detected by each of the other 12 probes were also mapped to different chromosomes. The bands detected by the same probe usually occurred in similar locations of different chromosomes. Loci detected by different DNA probes were often similarly arranged on different chromosomes. Chromosomes 8 and 9 showed colinearity of marker loci arrangement indicating a possible common origin. A segment on chromosome 9 was also very similar to the previously reported duplicated fragments on the ends of chromosomes 11 and 12 which were also detected in this study, indicating a likely common origin. Moreover, the various degrees of distributional similarity of the segments suggest a complex relationship among the chromosomes in the evolution of the rice genome. These results support the proposition that chromosome duplication and diversification may be a mechanism for the origin and evolution of the chromosomes in the rice genome.
水稻基因组中的节段重复
王石平* 刘克德 张启发
（华中农业大学作物遗传改良国家重点实验室，武汉430070）
摘要：利用 13个多拷贝探针 ,研究水稻 (OryzasativaL .)基因组第 8、9、11和 12染色体上的节段重复。由同一探针检测到的多拷贝位点通常位于不同染色体的相同部位。不同探针检测到的多拷贝位点在不同染色体上的位置顺序相同。第 8和第 9染色体上的相同多拷贝位点的线性排列 ,提示这两条染色体在进化上可能来源于同一原始染色体。而第 9染色体上的一个节段与前人报道的以及本研究进一步证实的第 11和第 12染色体短臂末端的重复区段相同 ,提示第 8、9、11和 12染色体可能在进化上存在同源性。这 4条染色体上表现出的不同程度的节段重复 ,为作者曾提出的水稻基因组形成和进化模式的推测提供了进一步的依据 ,即原始染色体的复制和基因的演变可能是水稻基因组形成和进化的重要机制。
关键词： 染色体复制；重复序列；分子标记定位；进化；水稻
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