Cytogenetic characters and the level of DNA methylation were studied in sugarbeet callus cultures with different morphogenic potential which were obtained from the same leaf explant. It was shown that non-morphogenic callus in comparison with the morphogenic one was characterized by the higher level of cell ploidy and of the frequency of chromosome structural rearrangements even at the early stages of cultivation. Overspiralization of chromosomes and formation of condensed chromatin were observerd in polyploid cells of non-morphogenic callus. At the same time cytosine hypermethylation occurs in site-specific CpCpGpG-sequences of DNA indicating the possible role of this DNA modification in the processes of genome rearrangements.
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