A new study challenges the theory of random mutations in genes

BEIJING, Jan. 15 (Xinhua) -- The randomness of genetic mutations has long been the foundation of biological evolution theory, but this classic view of biology has been challenged by a new study.

Researchers from the University of California, Davis and the Max Planck Institute for Developmental Biology in Germany recently published a paper in the British journal Nature, saying that they found through Arabidopsis experiments that genetic mutations are not random, but are carried out in a way that is beneficial to plants. The new discovery could fundamentally change the understanding of evolution, potentially helping scientists breed crops with better traits and even helping humans develop new therapies against diseases like cancer.

The picture shows Arabidopsis thaliana taken in the laboratory of the Institute of Plant Physiology and Ecology of the Chinese Academy of Sciences on September 14, 2018. Photo by Xinhua News Agency reporter Zhang Jiansong

A genetic mutation is a change in the composition or order of a base pair in DNA (deoxyribonucleic acid) that cannot be repaired. Existing theories suggest that initial genetic mutations are random, and that natural selection determines which mutations can be observed in the organism.

The international team bred Arabidopsis thaliana in the lab and sequenced its DNA to find out if there was a deep regularity in its mutations.

Compared to the human genome, which consists of 3 billion base pairs, the Arabidopsis genome contains only 120 million base pairs and is considered an ideal genetic experimental model plant.

The team found that there are low mutation rate regions in the Arabidopsis genome, and these low mutation rate regions have overexpression of genes essential for survival, such as genes involved in cell growth. In these low mutation rate regions, the mutation rate of genes is reduced by more than 50%, and the mutation rate of genes necessary for survival is even reduced by two-thirds.

The researchers explain that these truly important regions of the genome are also sensitive to the harmful effects of new mutations, so DNA damage repair is particularly effective in these regions.

The researchers also found that the way DNA is encased in different types of proteins is a good predictor of whether a gene will mutate, meaning that it is possible to predict which genes are more likely to mutate than others.

Detlev Weigel, corresponding author of the paper and scientific director of the Max Planck Institute for Developmental Biology in Germany, said: "This plant (Arabidopsis) has evolved a way to protect its most important places from mutations... This is exciting because we can even use these findings to think about how to protect human genes from mutation. ”