title: Differential impact of retrotransposon populations on the genome of allotetraploid tobacco (Nicotiana tabacum).
abstract: LTR-retrotransposons contribute substantially to the structural diversity of plant genomes. Recent models of genome evolution suggest that retrotransposon amplification is offset by removal of retrotransposon sequences, leading to a turnover of retrotransposon populations. While bursts of amplification have been documented, it is not known whether removal of retrotransposon sequences occurs continuously, or is triggered by specific stimuli over short evolutionary periods. In this work, we have characterized the evolutionary dynamics of four populations of copia-type retrotransposons in allotetraploid tobacco (Nicotiana tabacum) and its two diploid progenitors Nicotiana sylvestris and Nicotiana tomentosiformis. We have used SSAP (Sequence-Specific Amplification Polymorphism) to evaluate the contribution retrotransposons have made to the diversity of tobacco and its diploid progenitor species, to quantify the contribution each diploid progenitor has made to tobacco's retrotransposon populations, and to estimate losses or amplifications of retrotransposon sequences subsequent to tobacco's formation. Our results show that the tobacco genome derives from a turnover of retrotransposon sequences with removals concomitant with new insertions. We have detected unique behaviour specific to each retrotransposon population, with differences likely reflecting distinct evolutionary histories and activities of particular elements. Our results indicate that the retrotransposon content of a given plant species is strongly influenced by the host evolutionary history, with periods of rapid turnover of retrotransposon sequences stimulated by allopolyploidy.
authors: Laboratoire de Biologie Cellulaire, UR501, Institut Jean-Pierre Bourgin, INRA, 78026, Versailles cedex, France.
authors: Maud
authors: M
authors: Petit
authors: K Yoong
authors: KY
authors: Lim
authors: Emilie
authors: E
authors: Julio
authors: Charles
authors: C
authors: Poncet
authors: François
authors: F
authors: Dorlhac de Borne
authors: Ales
authors: A
authors: Kovarik
authors: Andrew R
authors: AR
authors: Leitch
authors: Marie-Angèle
authors: MA
authors: Grandbastien
authors: Corinne
authors: C
authors: Mhiri
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D004171:Diploidy; D019143:Evolution, Molecular; D016678:Genome; D018745:Genome, Plant; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D011003:Ploidies; D011110:Polymorphism, Genetic; D018626:Retroelements / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D020079:Terminal Repeat Sequences; D014026:Nicotiana / Q000235:genetics*
chemical_list: D018626:Retroelements