Bursts of retrotransposition reproduced in Arabidopsis
Bursts of retrotransposition reproduced in Arabidopsis
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DOI：
10.1038/nature08351
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发表时间：
2009-09-17
期刊：
影响因子：
64.8
通讯作者：
Kakutani, Tetsuji
中科院分区：
文献类型：
--
作者：
Tsukahara, Sayuri;Kobayashi, Akie;Kakutani, Tetsuji
逆转录转座子通过RNA中间体的逆转录增殖，构成植物基因组的主要部分（1，2）。植物在进化过程中经常通过长末端重复序列（LTR）逆转录转座子的快速增殖和缺失来改变基因组大小和组织（3，4）。整个拟南芥基因组中精确的转座子序列和影响表观遗传状态的反式作用突变使其成为研究转座子动力学的理想模式生物（5-9）。在这里，我们报告动员各种家庭的内源性A。通过遗传学和基因组学方法，用高分辨率基因组镶嵌阵列和染色质重塑基因DDM 1中的突变体（DNA甲基化减少1）鉴定了拟南芥LTR逆转录转座子（10，11）。使用多个自花授粉ddm 1突变株系，我们检测到拷贝数的增加，并验证了吉普赛家族（ATGP 3）和copia家族（ATCOPIA 13，ATCOPIA 21，ATCOPIA 93）中的各种反转录转座子，以及Mutator家族VANDAL 21的DNA转座子。一个突发的反转录发生随机和独立的每个元素，这表明一个额外的自催化过程。此外，在相关的拟南芥物种中鉴定的LTR反转录转座子的比较显示，这些元件的谱系特异性反转录突变确实发生在自然拟南芥种群中。最近在自然群体中爆发的反转录转座是针对着丝粒重复序列的，这可能比插入基因的危害小。ddm 1诱导的反转录转座子增殖和基因组重排模拟了转座子介导的基因组进化动力学，并提供了直接研究控制分子因素的实验系统。
Retrotransposons, which proliferate by reverse transcription of RNA intermediates, comprise a major portion of plant genomes(1,2). Plants often change the genome size and organization during evolution by rapid proliferation and deletion of long terminal repeat (LTR) retrotransposons(3,4). Precise transposon sequences throughout the Arabidopsis thaliana genome and the trans-acting mutations affecting epigenetic states make it an ideal model organism with which to study transposon dynamics(5-9). Here we report the mobilization of various families of endogenous A. thaliana LTR retrotransposons identified through genetic and genomic approaches with high-resolution genomic tiling arrays and mutants in the chromatin-remodelling gene DDM1 (DECREASE IN DNA METHYLATION1)(10,11). Using multiple lines of self-pollinated ddm1 mutant, we detected an increase in copy number, and verified this for various retrotransposons in a gypsy family (ATGP3) and copia families (ATCOPIA13, ATCOPIA21, ATCOPIA93), and also for a DNA transposon of a Mutator family, VANDAL21. A burst of retrotransposition occurred stochastically and independently for each element, suggesting an additional autocatalytic process. Furthermore, comparison of the identified LTR retrotransposons in related Arabidopsis species revealed that a lineage-specific burst of retrotransposition of these elements did indeed occur in natural Arabidopsis populations. The recent burst of retrotransposition in natural population is targeted to centromeric repeats, which is presumably less harmful than insertion into genes. The ddm1-induced retrotransposon proliferations and genome rearrangements mimic the transposon-mediated genome dynamics during evolution and provide experimental systems with which to investigate the controlling molecular factors directly.