title: Immediate unidirectional epigenetic reprogramming of NORs occurs independently of rDNA rearrangements in synthetic and natural forms of a polyploid species Brassica napus.
abstract: The dynamics of genome modification that occurred from the initial hybridization event to the stabilization of allopolyploid species remains largely unexplored. Here, we studied inheritance and expression of rDNA loci in the initial generations of Brassica napus allotetraploids (2n = 38, AACC) resynthesized from Brassica oleracea (2n = 18, CC) and B. rapa (2n = 20, AA) and compared the patterns to natural forms. Starting already from F1 generation, there was a strong uniparental silencing of B. oleracea genes. The epigenetic reprogramming was accompanied with immediate condensation of C-genome nucleolar organizer region (NOR) and progressive transgeneration hypermethylation of polymerase I promoters, mainly at CG sites. No such changes were observed in the A-genome NORs. Locus loss and gains affecting mainly non-NOR loci after the first allotetraploid meiosis did not influence established functional status of NORs. Collectively, epigenetic and genetic modifications in synthetic lines resemble events that accompanied formation of natural allopolyploid species.
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Le Rheu cedex, France.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Książczyk
authors.forename: Ales
authors.initials: A
authors.lastname: Kovarik
authors.forename: Frédérique
authors.initials: F
authors.lastname: Eber
authors.forename: Virginie
authors.initials: V
authors.lastname: Huteau
authors.forename: Lucie
authors.initials: L
authors.lastname: Khaitova
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Tesarikova
authors.forename: Olivier
authors.initials: O
authors.lastname: Coriton
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Chèvre
mesh_terms: D029688:Brassica napus / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D018744:DNA, Plant / Q000235:genetics* / Q000378:metabolism; D004275:DNA, Ribosomal / Q000235:genetics* / Q000378:metabolism; D057890:Epigenomics; D015321:Gene Rearrangement; D006824:Hybridization, Genetic; D008540:Meiosis; D009697:Nucleolus Organizer Region / Q000235:genetics* / Q000378:metabolism; D011123:Polyploidy
chemical_list: D018744:DNA, Plant; D004275:DNA, Ribosomal