DNA mutations don’t happen randomly – the discovery is transforming our view of evolution

Overcome the odds in a game of chance for a boom

The discovery that plants protect their essential genes is changing our view of evolution.

mutations Thele Kress

Cress of the Trinity (Arabidopsis thaliana). Credit: Max Planck Institute for Biology Tübingen

Protection of plants with harmful mutations

The researchers planted samples of the widely distributed weed Arabidopsis thaliana In a protected laboratory environment, where all plants, including those with harmful mutations, can reproduce. These deleterious mutations are usually quickly removed by the pressures of selection prevailing in nature and thus disappear before they can be observed. By analyzing the genomes of hundreds of plants grown in the laboratory, the scientist was able to identify thousands of mutations as they appeared.

Sophisticated statistical analyzes revealed that these mutations were by no means randomly distributed in the genome, as the researchers expected. Instead, they found stretches of the genome where mutations were rare, and others where mutations were more common. In those regions with few mutations, the genes required in each cell and thus essential for the survival of each plant were greatly over-represented. “These are regions of the genome that are most sensitive to the deleterious effects of new mutations, and thus DNA damage repair appears to be particularly effective in these regions,” Weigl says. It’s as if evolution was playing with loaded dice – it reduces the risk of damaging the most vital genes.

Thale Cress in Greenhouse

Cress love multiply under laboratory conditions in the greenhouse. Credit: Max Planck Institute for Biology Tübingen

A new perspective on classical evolutionary theory

The scientists found that the different types of proteins that DNA wraps around in the cell nucleus are closely associated with the emergence of mutations. “It gives us a good idea of ​​what’s going on, so that we can predict which genes are most likely to change than others,” Munro says.

Weigel emphasized how the results were completely unexpected in light of classical evolution theory: “It has long been known that, during the course of evolution, more mutations accumulate in certain regions of the genome than in others. At first glance, what we found seems to contradict the accepted wisdom that this It only reflects natural selection that removes most mutations before they can actually be observed,” he explains. However, despite the uneven distribution of mutations in the model genome, the important regions are not completely devoid of them, and therefore these regions can also evolve, albeit at a slower rate than other parts of the genome.

Future uses in education and medical research

“The plant has developed a way to protect its most important genes from mutations,” Munro says. “This is exciting because we can even use these discoveries to think about how to protect human genes from mutations.” In the future, one might use them to predict which genes are the best targets for reproduction because they evolve rapidly, or which are most likely to cause disease in humans.

Reference: “Mutational bias reflects natural selection in Arabidopsis thaliana” by J. Gray Monroe, Thanvi Srikant, Pablo Carbonel-Bigerano, Claude Becker, Marielle Linsink, Moses Exposito Alonso, Mary Klein, Julia Hildebrandt, Manuela Neumann, Daniel Klebstein, Mau-Lun Wing, Eric Imbert, John Agren, Matthew T. Rutter, Charles P. Finnster January 12, 2022, temper nature.
DOI: 10.1038 / s41586-021-04269-6

Most of the work was carried out at the Max Planck Institute for Biology (formerly the Max Planck Institute for Developmental Biology), and is now ongoing there and at the University of California, Davis. Researchers from the Carnegie Institution for Science, Stanford University, Westfield State University, Montpellier University, Uppsala University, College of Charleston, and South Dakota State University also contributed to the work. Funding came from the Max Planck Society, with additional funding from the National Science Foundation and the German Research Foundation.

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