Transcription activity of rRNA genes correlates with a tendency towards intergenomic homogenization in Nicotiana allotetraploids
Transcription activity of rRNA genes correlates with a tendency towards intergenomic homogenization in Nicotiana allotetraploids
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DOI：
10.1111/j.1469-8137.2007.02034.x
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发表时间：
2007-01-01
期刊：
影响因子：
9.4
通讯作者：
Kovarik, Ales
中科院分区：
文献类型：
--
作者：
Dadejova, Martina;Lim, K. Yoong;Kovarik, Ales
本文研究了三种天然烟草异源多倍体（给出了二倍体亲本的最近的活后代）、N. rustica（N. paniculata x N. undulata）、N. tabacum（N. sylvestris x N. tomentosiformis）和N. arentsii（N. undulata x N. Wigandioides）、人工合成的F-1杂种和异源多倍体。arentsii > N. tabacum > N.乡下人双亲rDNA单位在其中一个亚基因组中的持续存在与它们的转录活性和可能的异染色质化有关。在人工杂种和多倍体中，只有N. paniculata x N. undulata表现出强烈的单亲转录沉默的rDNA触发已经在F-1.表观遗传模式的表达建立在异源多倍体细胞核形成早期可能会使单位易感或抵抗同质化在较长的时间框架。我们认为，核仁相关的转录使rDNA单位容易受到均质化，而表观遗传失活的单位，以及从核仁分离，保持未转换。
This paper establishes relationships between two aspects of ribosomal DNA (rDNA) biology: epigenetic silencing of rDNA loci; and homogenization leading to concerted evolution.Here, we examined rDNA inheritance and expression patterns in three natural Nicotiana allopolyploids (closest living descendants of diploid parents are given), N. rustica (N. paniculata x N. undulata), N. tabacum (N. sylvestris x N. tomentosiformis) and N. arentsii (N. undulata x N. wigandioides), and synthetic F-1 hybrids and allopolyploids.The extent of interlocus rDNA homogenization decreased in the direction N. arentsii > N. tabacum > N. rustica. The persistence of parental rDNA units in one of the subgenomes was associated with their transcription inactivity and likely heterochromatization. Of synthetic hybrids and polyploids only N. paniculata x N. undulata showed strong uniparental transcriptional silencing of rDNA triggered already in F-1.Epigenetic patterns of expression established early in allopolyploid nucleus formation may render units susceptible or resistant to homogenization over longer time-frames. We propose that nucleolus-associated transcription leaves rDNA units vulnerable to homogenization, while epigenetically inactivated units, well-separated from the nucleolus, remain unconverted.