With the use of CRISPR/Cas9, scientists have succeeded in exchanging larger sections of DNA between two different chromosomes in the model plant Arabidopsis thaliana. To do this, they used two gRNAs that guided the gene scissors to a target region at the first and second chromosomes of the plant. Subsequently, the gene scissors introduce a DNA double-strand break there. In a few plants it was demonstrated that there was an exchange of chromosomal pieces between the two chromosomes – a process that is called reciprocal translocation in genetics. These changes are heritable and have been shown to be stable in subsequent generations. In addition to chromosomes 1 and 2, the scientists carried out similar experiments with chromosomes 1 and 5 generating plants in which parts of these two chromosomes are exchanged.
The scientists use A. thaliana, a plant that has a relatively small genome and two sets of chromosomes. This “chromosomal editing” will be considerably more difficult in plants with more complex genomes, because there can be significantly more DNA areas containing the target sequence, which can lead to undesired restructuring (wheat, for example, has a very large genetic material with 6 chromosome sets).
According to the authors, this procedure can be used to separate so-called linked genes from one another. By exchanging pieces between different chromosomes, desired and undesired properties can be separated from each other, which are normally inherited together. A specific example for the decoupling of two genes is not described in the article. In the case of an actual application, a comparison of the gene expression of such genome-edited plants with the original plants should be carried out to check the extent to which the decoupled genes are formed and whether the gene expression of other genes is impaired.