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Transcription activity of rRNA genes correlates with a tendency towards intergenomic homogenization in Nicotiana allotetraploids
Author(s) -
Dadejová Martina,
Lim K. Yoong,
SouckováSkalická Kamila,
Matyášek Roman,
Grandbastien MarieAngéle,
Leitch Andrew,
Kovařík Aleš
Publication year - 2007
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2007.02034.x
Subject(s) - biology , ribosomal dna , nucleolus , genetics , epigenetics , nicotiana tabacum , ribosomal rna , gene , nicotiana , hybrid , botany , phylogenetics , solanaceae , cytoplasm
Summary• 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 × N. undulata ), N. tabacum ( N. sylvestris × N. tomentosiformis ) and N. arentsii ( N. undulata × 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 × 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.