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Transcription activity of rRNA genes correlates with a tendency towards intergenomic homogenization in Nicotiana allotetraploids
被引:52
作者:
Dadejova, Martina
Lim, K. Yoong
Souckova-Skalicka, Kamila
Matyasek, Roman
Grandbastien, Marie-Angele
Leitch, Andrew
Kovarik, Ales
[1
]
机构:
[1] Acad Sci Czech Republ, Inst Biophys, CZ-61265 Brno, Czech Republic
[2] Queen Mary Univ London, Sch Biol & Chem Sci, London E1 4NS, England
[3] INRA, Ctr Versailles, Biol Cellulaire Lab, Inst Jean Pierre Bourgin, F-78026 Versailles, France
基金:
英国自然环境研究理事会;
关键词:
gene conversion;
nucleolar dominance;
polyploidy;
rDNA silencing;
ribosomal RNA;
D O I:
10.1111/j.1469-8137.2007.02034.x
中图分类号:
Q94 [植物学];
学科分类号:
071001 ;
摘要:
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.
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页码:658 / 668
页数:11
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