ibclogo XVI International Botanical Congess


Abstract Number: 5120
Session = 19.15.4


THE ROLE OF DOUBLE-STRAND BREAK (DSB) REPAIR IN GENOMIC CHANGE IN PLANTS.


Holger Puchta, IPK, D-06466 Gatersleben, Germany


By using the highly specific restriction endonuclease I-SceI we were able to elucidate molecular mechanisms of homologous and illegitimate DSB repair in somatic plant cells. In homologous DSB repair the ends of the break are repaired independently-one end can be even repaired via illegitimate recombination. In illegitimate DSB repair besides deletions, insertions of genomic sequences were found at the break site. All different kinds of genomic change can be explained by an unifying concept, the synthesis-dependent strand annealing" model of recombination. Although this model allows the copying of almost any DNA into new positions in the genome, it disfavors crossovers between ectopic positions on different chromosomes. Thus, multiple genomic change is tolerated at break sites, but an overall destabilization of highly repetitive plant genomes is suppressed.


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