MADRID, 12 (EUROPA PRESS)
A new study challenges the evolutionary theory that DNA mutations are random. Their findings could represent advances in plant cultivation and human genetics, according to researchers from the University of California, in the United States, and the Max Planck Institute for Developmental Biology, in Germany, published in the journal Nature.
The findings radically change our understanding of evolution and could one day help researchers grow better crops or even help humans fight cancer, the researchers explain.
Mutations occur when DNA is damaged and not repaired, creating new variation. The scientists wanted to know if the mutation was purely random or something deeper, and what they found was unexpected.
“We had always thought that the mutation was basically random throughout the genome,” explains Gray Monroe, assistant professor in the UC Davis Department of Plant Sciences and lead author of the paper. “It turns out that the mutation is very non-random, and it is. in a way that benefits the plant. It’s a whole new way of thinking about mutation. “
The researchers spent three years sequencing the DNA of hundreds of Arabidopsis thaliana, a small flowering herb considered the “laboratory rat among plants” due to its relatively small genome of about 120 million base pairs. Humans, by comparison, are about 3 billion base pairs. “It is a model organism for genetics,” Monroe notes.
The work began at the Max Planck Institute, where the researchers grew specimens in a protected laboratory environment, allowing plants with defects that would not have survived in the wild to survive in a controlled space.
Sequencing those hundreds of ‘Arabidopsis thaliana’ plants revealed more than a million mutations. Within these mutations, a non-random pattern was revealed, contrary to what was expected.
“At first glance, what we found seemed to contradict the established theory that initial mutations are totally random and that only natural selection determines which mutations are observed in organisms,” says Detlef Weigel, scientific director of the Max Planck Institute and lead author. of the study.
Instead of randomness, they found areas of the genome with low mutation rates. In these areas, they were surprised to discover an over-representation of essential genes, such as those involved in cell growth and gene expression.
“These are the really important regions of the genome – Monroe points out -” The most important areas from the biological point of view are those that are protected from mutations.
These areas are also sensitive to the harmful effects of new mutations. “DNA damage repair therefore appears to be particularly effective in these regions,” adds Weigel.
The scientists found that the way DNA wrapped itself around different types of proteins was a good indicator of whether or not a gene would mutate. “It means that we can predict which genes are more likely to mutate than others and it gives us a good idea of what is going on,” Weigel emphasizes.
The findings add a surprising twist to Charles Darwin’s theory of evolution by natural selection, revealing that the plant has evolved to protect its genes from mutation to ensure its survival, the researchers say.
“The plant has evolved to protect its most important sites from mutation,” Weigel explains. “This is exciting because we could even use these discoveries to think about how to protect human genes from mutation.”
Knowing why some regions of the genome mutate more than others could help breeders who depend on genetic variation to develop better crops. Scientists could also use the information to better predict or develop new treatments for diseases such as cancer caused by mutations.
“Our findings provide a more complete explanation of the forces that drive patterns of natural variation; they should inspire new avenues of theoretical and practical research on the role of mutation in evolution,” the article concludes.