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转座因子。因此，我们在进化方面的理解积累了转座因子引起的遗传变异的信息。然而，大多数这些遗传变异已被描述在物种形成过程中的基因组多样性。本研究主要研究水稻品种内的遗传变异。我们有间接证据表明，水稻转座子m-Ping在50多年前建立并广泛分布于整个日本的主要水稻品种越光中发生了易位。越光的样本是从福岛到北方14个县的84个地点采集的。通过转座子展示，使用m-Ping引物，在这些越光收藏品中观察到总共36个多态性。其中4个转座子明显来源于越光以外的地方，因为其他转座子也表现出与m-Ping相似的多态性。另外32种类型被认为是越光育种后发生的m-Ping易位。结果表明，转座子的转座可以很容易地遗传到下一代，并且所产生的遗传变异在同一品种的不同群体中得以保持。

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.