For the first time, researchers at the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) have reduced the size of — and in some cases completely removed — chromosomes in plants with large genomes, including wheat.
The team used the CRISPR/Cas gene-editing tool to target highly repetitive sections of DNA. Their findings, published in Plant Communications, could help significantly speed up plant breeding.
While scientists have already been able to manipulate entire chromosomes in model plants such as Arabidopsis thaliana, doing so in crops with large genomes, such as wheat, has remained difficult. The IPK team investigated whether satellite DNA — highly repetitive DNA sequences — could serve as a target for CRISPR. By cutting many identical sequences at once, they aimed to affect the entire chromosome.
To do this, the researchers introduced CRISPR components into the plants using a virus-based system. This avoided lengthy traditional transformation methods and enabled highly efficient chromosome modifications.
“In our study, we were actually able to demonstrate for the first time that chromosomes can be efficiently reduced in size by making targeted cuts in satellite DNA,” says Dr. Jianyong Chen, the study’s first author.
This marks a significant breakthrough, as such changes had previously occurred only by chance, according to a press release.
The process can be compared to cutting a rope in several places at once: the rope becomes unstable and eventually breaks. Similarly, when multiple cuts are made in a chromosome at the same time, it can become unstable. In some cases, the method led to the loss of entire chromosomes.
“If too many breaks occur, the cell can no longer repair the chromosome efficiently—it is lost entirely,” explains Prof. Dr. Andreas Houben, head of the IPK’s research group “Chromosome Structure and Function.”
Faulty repair processes can also produce new chromosome structures known as isochromosomes. Prof. Dr. Houben says these changes can create new genetic variants, opening new opportunities for breeding resistant wheat and other crops.
The study shows that plant genomes can be modified with unprecedented precision. It also highlights satellite DNA — once dismissed as “genetic ballast” — as an effective target for modern breeding tools.
