Abstract
The union of different genomes in the same nucleus frequently results in hybrid genotypes with improved genome plasticity related to both genome remodeling events and changes in gene expression. Most modern cereal crops are polyploid species. Triticale, synthesized by the cross between wheat and rye, constitutes an excellent model to study polyploidization functional implications. We intend to attain a deeper knowledge of dispersed repetitive sequence involvement in parental genome reshuffle in triticale and in wheat-rye addition lines that have the entire wheat genome plus each rye chromosome pair. Through Random Amplified Polymorphic DNA (RAPD) analysis with OPH20 10-mer primer we unraveled clear alterations corresponding to the loss of specific bands from both parental genomes. Moreover, the sequential nature of those events was revealed by the increased absence of rye-origin bands in wheat-rye addition lines in comparison with triticale. Remodeled band sequencing revealed that both repetitive and coding genome domains are affected in wheat-rye hybrid genotypes. Additionally, the amplification and sequencing of pSc20H internal segments showed that the disappearance of parental bands may result from restricted sequence alterations and unraveled the involvement of wheat/rye related repetitive sequences in genome adjustment needed for hybrid plant stabilization.
Highlights
Repetitive DNA sequences have been extensively studied in large plant genomes, corresponding up to 83% and 92% of Triticum aestivum and Secale cereale genomes, respectively [1]
Repetitive sequence fraction is strongly implicated in functional genome structure [3], and transposable elements have been successfully used as molecular tools to characterize complex plant genomes [4,5,6,7]
OPH20 Random Amplified Polymorphic DNA (RAPD) marker and pSc20H sequence [6] were used to evaluate hybrid genome rearrangements and identify sequences involved in wheat-rye genotypes adjustment in octoploid triticale and in the seven wheat-rye addition lines
Summary
Repetitive DNA sequences have been extensively studied in large plant genomes, corresponding up to 83% and 92% of Triticum aestivum and Secale cereale genomes, respectively [1]. These interspersed repetitive sequences correspond mainly to transposable elements that are ubiquitous in all organisms and represent a considerable genome fraction, in plants with large genomes [2]. The elucidation of mechanisms underlying parental adjustment in hybrid genotypes has revealed the role of transposable elements in genome merger induced restructuring [8], in Triticeae hybrids and polyploids species, such as distinct synthetic wheats and triticales (reviewed in [9]). The involvement of transposable-related sequences in polyploidization induced genome evolution in the wheat-rye system was evaluated through Inter Retrotransposons Amplified Polymorphism (IRAP) and Retrotransposons
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