Genome merger: from sequence rearrangements in triticale to their elimination in wheat-rye addition lines.
Genetic and epigenetic modifications resulting from different genomes adjusting to a common nuclear environment have been observed in polyploids. Sequence restructuring within genomes involving retrotransposon/microsatellite-rich regions has been reported in triticale. The present study uses inter-retrotransposon amplified polymorphisms (IRAP) and retrotransposon microsatellite amplified polymorphisms (REMAP) to assess genome rearrangements in wheat-rye addition lines obtained by the controlled backcrossing of octoploid triticale to hexaploid wheat followed by self-fertilization. The comparative analysis of IRAP and REMAP banding profiles, involving a complete set of wheat-rye addition lines, and their parental species revealed in those lines the presence of wheat-origin bands absent in triticale, and the absence of rye-origin and triticale-specific bands. The presence in triticale x wheat backcrosses (BC) of rye-origin bands that were absent in the addition lines demonstrated that genomic rearrangement events were not a direct consequence of backcrossing, but resulted from further genome structural rearrangements in the BC plant progeny. PCR experiments using primers designed from different rye-origin sequences showed that the absence of a rye-origin band in wheat-rye addition lines results from sequence elimination rather than restrict changes on primer annealing sites, as noted in triticale. The level of genome restructuring events evaluated in all seven wheat-rye addition lines, compared to triticale, indicated that the unbalanced genome merger situation observed in the addition lines induced a new round of genome rearrangement, suggesting that the lesser the amount of rye chromatin introgressed into wheat the larger the outcome of genome reshuffling.
Bento
Miguel
M
Centro de Botânica Aplicada à Agricultura, Secção de Genética, Instituto Superior de Agronomia, Technical University of Lisbon, Tapada da Ajuda, 1349-017, Lisbon, Portugal.
Gustafson
Perry
P
Viegas
Wanda
W
Silva
Manuela
M
D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D002523:Edible Grain / Q000235:genetics*; D014644:Genetic Variation; D018745:Genome, Plant; D007178:Inbreeding; D018895:Microsatellite Repeats; D010641:Phenotype; D016133:Polymerase Chain Reaction; D018626:Retroelements / Q000235:genetics*; D012434:Secale / Q000235:genetics*; D014908:Triticum / Q000235:genetics*
D018744:DNA, Plant; D018626:Retroelements
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