Studies on Evolution of Mutator transposable element in Grass Family

克隆了玉米Mutator转座元件的水稻同源物，该同源物与玉米Mutator转座酶（TNP）结构域具有相似性。由426bp组成的精确结构域能够翻译成142个氨基酸。在DNA水平上同源性为69%，在氨基酸水平上同源性为80%。水稻品种在其基因组中至少携带3个拷贝，而野生近缘种携带不同数量的拷贝和RFLP模式。RT-PCR证实该结构域在粳稻株系中有表达，而在籼稻株系幼苗期和叶片成熟期无表达。以北海道一种著名的地方品种为材料，通过自花授粉获得了变异品系，变异品系出现了白化、嵌合和双胚等突变。他们还提出了用水稻tnp样结构域探测的RFLPs。由于后代是几代自花授粉，并且在纯合子条件下仍然携带隐性矮子-1基因，因此没有理由相信花粉和其他污染源是RFLPs的来源。我们还从后代中获得了白化病、氯化病和双胚胎突变体。阿卡奇的其他后代也携带了几个突变基因，这些基因是通过一个世纪的自花授粉自发产生的，如无芒-1、无芒-2、侏儒-2和波动的rachis-1。这种变异对植物育种产生影响，使其种植面积向北扩大。将讨论作为可变种群的其他来源。亚种水平杂交产生的种群，就像果蝇的杂交发育不良系统。在他们的后代中产生了至少0.5%的突变体。每代与这些黄化现象相关的基因比例为1/20。

Rice homolog to maize Mutator transposable element was cloned, which has similarity to transposase (TNP) domain of the Mutator element in maize. The exact domain consisting of 426bp is capable to translate into142 amino acids. and share 69% homology at DNA level and 80% at amino acids level. Rice cultlvars carry at least three copies in their genomes and wild relatives carry different number of copies and RFLP patterns. Expression of the domain was confirmed by RT-PCR with Japonica strains but not in lndica strains at seedling and mature leaf stage. Mutable strains were generated through self pollination from a famous Hokkaido's local cultivar, which showed some mutants such as albino, chimera and twin embryo. They also presented RFLPs probed with rice TNP-like domain. There is no reason to believe pollen and other contamination sources for the RFLPs because the progeny was self-pollinated through several generations and stil carried recessive dwarf-1 gene as homozygous condition. And we also obtalned albino, chlorina and twin embryo mutants from the progeny. Other progenies from Akage are also known to carry several mutant genes generated spontaneously through self-pollination such as awnless-1, awnless-2, dwarf-2 and Undulated rachis-1 for one century. Such mutabllity affected to plant breeding, which enlarge their cultivated area up to more north region. Other sources as mutable populations will be discussed. The populations generated from subspecies level-crosses like a hybrid dysgenesis system in Drosophila. At least 0.5% mutants were generated in their progenies. The ratio would be 1/20 genes related to those chlorosis phenomena per generation.