Allopolyploids represent natural experiments in which DNA sequences from different species are combined into a single nucleus and then coevolve, enabling us to follow the parental genomes, their interactions and evolution over time. Here, we examine the fate of satellite DNA over 5 million yr of divergence in plant genus Nicotiana (family Solanaceae). We isolated subtelomeric, tandemly repeated satellite DNA from Nicotiana diploid and allopolyploid species and analysed patterns of inheritance and divergence by sequence analysis, Southern blot hybridization and fluorescent in situ hybridization (FISH). We observed that parental satellite sequences redistribute around the genome in allopolyploids of Nicotiana section Polydicliae, formed c. 1 million yr ago (Mya), and that new satellite repeats evolved and amplified in section Repandae, which was formed c. 5 Mya. In some cases that process involved the complete replacement of parental satellite sequences. The rate of satellite repeat replacement is faster than theoretical predictions assuming the mechanism involved is unequal recombination and crossing-over. Instead we propose that this mechanism occurs with the deletion of large chromatin blocks and reamplification, perhaps via rolling circle replication.

Institute of Biophysics Academy of Sciences of the Czech Republic CZ 612 65 Brno Czech Republic

References provided by Crossref.org

Repeat Dynamics across Timescales: A Perspective from Sibling Allotetraploid Marsh Orchids (Dactylorhiza majalis s.l.)

DNA Transposon Expansion is Associated with Genome Size Increase in Mudminnows

Evolution of Tandem Repeats Is Mirroring Post-polyploid Cladogenesis in Heliophila (Brassicaceae)

Natural History of a Satellite DNA Family: From the Ancestral Genome Component to Species-Specific Sequences, Concerted and Non-Concerted Evolution

Higher-order organisation of extremely amplified, potentially functional and massively methylated 5S rDNA in European pikes (Esox sp.)

Gene conversion events and variable degree of homogenization of rDNA loci in cultivars of Brassica napus

From Mendel's discovery on pea to today's plant genetics and breeding : Commemorating the 150th anniversary of the reading of Mendel's discovery

The expansion of heterochromatin blocks in rye reflects the co-amplification of tandem repeats and adjacent transposable elements

Differential amplification of satellite PaB6 in chromosomally hypervariable Prospero autumnale complex (Hyacinthaceae)

Next generation sequencing analysis reveals a relationship between rDNA unit diversity and locus number in Nicotiana diploids