Derepression of the plant Chromovirus LORE1 induces germline transposition in regenerated plants.
Derepression of the plant Chromovirus LORE1 induces germline transposition in regenerated plants.
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DOI：
10.1371/journal.pgen.1000868
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发表时间：
2010-03-05
期刊：
影响因子：
4.5
通讯作者：
Hirochika H
中科院分区：
文献类型：
--
作者：
Fukai E;Umehara Y;Sato S;Endo M;Kouchi H;Hayashi M;Stougaard J;Hirochika H
转座因子在真核生物基因组中占很大比例。长末端重复序列（LTR）反转录转座子是植物中数量非常丰富的一类转座因子。最近的研究已经确定了色病毒是一个广泛分布的吉普赛元素谱系。这些元件在它们的整合酶中含有染色质结构域，这表明它们倾向于插入异染色质。反过来，这种偏好可能有助于在宿主基因组中观察到的异染色质模式。尽管它们对我们理解植物基因组动态和进化具有潜在的重要性，但控制色病毒行为及其活动的调节机制在很大程度上仍然没有被描述。在这里，我们报告了一个详细的分析的时空活动的植物染色体病毒在内源宿主。我们研究了LORE1a，一个成员的内源性染色体病毒LORE1家族的模式豆科植物百脉根。我们发现，这种染色体病毒是stochastoline去抑制再生的植物种群从去分化细胞和LORE1a转座在雄性生殖系。5′ LTR及其周围区域的亚硫酸氢盐测序表明，组织培养诱导LORE 1a表观遗传沉默的丧失。由于LTR启动子活性是花粉特异性的，如通过分析含有LTR：：GUS融合的转基因植物所示，我们得出结论，雄性生殖系特异性LORE1a在花粉粒中的转座由其自身的顺式元件转录控制。LORE 1a拷贝的新插入位点经常出现在基因区域，没有表现出强烈的插入偏好。LORE 1的这些独特的新特征表明，这种染色体病毒具有相当大的潜力，在宿主植物种群中产生遗传和表观遗传多样性。我们的研究结果还定义了LORE1a作为遗传工具的使用条件。与动物的种系分化在胚胎发生早期开始相反，植物的种系分化在生殖发育期间的成体阶段开始。转座因子在体细胞和配子细胞中的转座可以传递给下一代。因此，植物基因组可能含有转座因子，表现出多种组织特异性活性。迄今为止，LTR反转录转座子，植物中最丰富的一类转座因子的时空活动还没有得到很好的表征。在这里，我们报告了一个植物LTR反转录转座子在内源系统中的时空转座模式的详细分析。使用模式豆科植物莲花，我们发现，LORE 1a，属于吉普赛超家族的染色体病毒LORE 1家族的成员，通过组织培养表观遗传去抑制。激活是随机的，去阻遏在再生植株中得以维持。这一特征使得在完整的植物中追踪反转录转座子的原始时空活动成为可能。我们确定，植物染色体病毒逆转录转座主要在雄性生殖系，没有明显的插入染色体区域的偏好。这一发现表明，在考虑转座因子对宿主基因组动态和进化的影响时，应考虑转座因子的组织特异性。
Transposable elements represent a large proportion of the eukaryotic genomes. Long Terminal Repeat (LTR) retrotransposons are very abundant and constitute the predominant family of transposable elements in plants. Recent studies have identified chromoviruses to be a widely distributed lineage of Gypsy elements. These elements contain chromodomains in their integrases, which suggests a preference for insertion into heterochromatin. In turn, this preference might have contributed to the patterning of heterochromatin observed in host genomes. Despite their potential importance for our understanding of plant genome dynamics and evolution, the regulatory mechanisms governing the behavior of chromoviruses and their activities remain largely uncharacterized. Here, we report a detailed analysis of the spatio-temporal activity of a plant chromovirus in the endogenous host. We examined LORE1a, a member of the endogenous chromovirus LORE1 family from the model legume Lotus japonicus. We found that this chromovirus is stochastically de-repressed in plant populations regenerated from de-differentiated cells and that LORE1a transposes in the male germline. Bisulfite sequencing of the 5′ LTR and its surrounding region suggests that tissue culture induces a loss of epigenetic silencing of LORE1a. Since LTR promoter activity is pollen specific, as shown by the analysis of transgenic plants containing an LTR::GUS fusion, we conclude that male germline-specific LORE1a transposition in pollen grains is controlled transcriptionally by its own cis-elements. New insertion sites of LORE1a copies were frequently found in genic regions and show no strong insertional preferences. These distinctive novel features of LORE1 indicate that this chromovirus has considerable potential for generating genetic and epigenetic diversity in the host plant population. Our results also define conditions for the use of LORE1a as a genetic tool. In contrast to animals, where germline differentiation initiates early in embryogenesis, germline differentiation in plants starts in the adult phase during reproductive development. Transpositions of transposable elements in both somatic and gametic cells can be transmitted to the next generation. As a result, plant genomes may contain transposable elements exhibiting a variety of tissue-specific activities. Thus far, the spatio-temporal activity of LTR retrotransposons, the most abundant class of transposable elements in plants, has not been well characterized. Here, we report a detailed analysis of the spatio-temporal transposition pattern of a plant LTR retrotransposon in the endogenous system. Using the model legume Lotus japonicus, we found that LORE1a, a member of the chromovirus LORE1 family that belongs to the Gypsy superfamily, was epigenetically de-repressed via tissue culture. Activation was stochastic and derepression was maintained in regenerated plants. This feature made it possible to trace the original spatio-temporal activity of the retrotransposon in the intact plants. We determined that the plant chromovirus retrotransposes mainly in the male germline, without obvious insertional preferences for chromosomal regions. This finding suggests that the tissue specificity of transposable elements should be taken into account when considering their impact on the host genome dynamics and evolution.
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影响因子：
14.9
作者：
MCCLELLAND, M;NELSON, M;RASCHKE, E
通讯作者：
RASCHKE, E
影响因子：
3.1
作者：
Cheng, Chaoyang;Daigen, Masaaki;Hirochika, Hirohiko
通讯作者：
Hirochika, Hirohiko
DOI：
10.1073/pnas.93.15.7783
发表时间：
1996-07-23
影响因子：
11.1
作者：
Hirochika, H;Sugimoto, K;Kanda, M
通讯作者：
Kanda, M
影响因子：
64.8
作者：
Jaillon, Olivier;Aury, Jean-Marc;Wincker, Patrick
通讯作者：
Wincker, Patrick
影响因子：
7.2
作者：
Clough, SJ;Bent, AF
通讯作者：
Bent, AF