Evaluation of the genome stability in the rice cultivars based on indication of the transposable elements

近年来，在植物中发现了大量的活性转座子。因此，我们在进化方面的理解积累了关于转座元件引起的遗传变异的信息。然而，这些遗传变异中的大多数都是在物种形成过程中描述的基因组多样性。本研究以水稻品种内的遗传变异为研究对象。我们有间接证据表明，水稻转座子m-ping在顶级水稻品种Koshihikari中发生了转位。Koshihikari成立于50多年前，在日本各地广泛分布。Koshihikari的样本是从福岛到朝鲜14个县的84个地点采集的。利用m-ping转座子显示技术，在这些Koshihikari种质中共检测到36个多态性。在这些样品中，有4个明显来自Koshihikari以外的地方，因为其他转座子也表现出与m-Ping相似的多态性。其他32种类型被认为是m-ping换位，发生在Koshihikari被培育之后。结果表明，转座子的转座很容易遗传给下一代，所产生的遗传变异在同一品种内的不同群体中保持不变。

Recently, active transposable elements have been abundantly found in plants. Thus, our understanding in evolutionary aspects has accumulated information on the genetic variations caused by transposable elements. However, most of these genetic variations have been described on the genome diversity during speciation. This study was focused on the genetic variations within the cultivar of rice. We have circumstantial evidence of the transpositions of the rice transposon, m-Ping, within the premier rice cultivar, Koshihikari, which was established more than 50 years ago and wildly distributed in the whole Japan. The Koshihikari samples were collected from 84 locations from Fukushima to 14 prefectures in the North. A total of 36 polymorphisms were observed in these Koshihikari collections by transposon display using m-Ping primers. Among these collections, four were obviously originated from other than Koshihikari because the other transposons also showed the similar polymorphisms with m-Ping. It was strongly assumed that the other 32 types are the m-Ping transpositions, which occurred after the Koshihikari was bred. The results represent that transpositions of the transposons can readily inherit to the next generation, and the produced genetic variations are maintained in the different populations within the same cultivars.