A team of Chinese scientists claims to have shown that evolution can also occur through hereditary adaptation to the environment and not just as a consequence of genetic arbitrariness.
A new study rekindles an old controversy about evolution of living beings among the French naturalist Jean-Baptiste Lamarck e Charles Darwin.
The authors of the study, conducted by a team of research at the Chinese Academy of Sciences (CAS) say they have shown that rice plants can convey survival characteristics learned from your descendants.
Throughout the study, scientists exposed cold -sensitive rice plants Stress for low temperatures during multiple generations, selecting to reproduce those that best resisted low temperatures.
This process produced rice strains with cold tolerance stable and hereditary persisted for at least five generationsEven after the removal of the cold stress, explains one from CAS.
This discovery Supports Lamarck’s hypothesis and challenges the idea that evolution occurs only through random genetic variationas Darwin argued.
Lamarck and Darwin proposed theories about the evolution in the nineteenth century that decisively influenced our understanding of evolution to this day.
The two scientists opposed the predominant belief at that time I assumed immutability of species And they argued that life forms change hopelessly over time.
However, their explanations of how evolution occur were fundamentally different and are often considered irreconcilable.
A rivalry that lasts centuries
Lamarck, with his famous Giraffe Theorystated that the necks of these animals they grew up so much because they had to stretch To reach the highest leaves of the trees, explains the.
This acquired genetic characteristic (epigenetic) It was transferred to the following generations, who also had a long neck like their parents.
Darwin’s evolutionary theory, in turn, It is based on natural selection. The naturalist argued that individuals in a population vary naturally and randomly, and those specimens with better characteristics adapted It is more likely to survive and reproduce to your environment.
This theory became the dominant scientific explanation to understand evolution.
For Darwin, the longer necks could reach more food and were more likely to survive and reproduceconveying this genetic characteristic to its offspring.
The new, published last week, is not the first to reinforce the Lamarckian idea of epigenetic inheritance (the transmission of characteristics through distinct mechanisms from the changes in the sequence of DNA), but is one of the scientific demonstrations. more direct and solid to date of this theory in a natural system.
Frost resistant rice
The team was able to demonstrate that the varieties of rice that grow in the cold northeast of China are able to adapt to these extreme conditions in a stable and non -genetic.
Generally, rice plants are very sensitive to low temperatures and these conditions negatively affect their growth and yield.
The investigators examined Several varieties of Asian rice and selected one that was more sensitive to the cold and produced fewer seeds in these environments. The team subjected the still growing plants to cold stress for a week and then let them grow the normal temperature.
Then they collected the seeds of the plant that produced the most and germinated the seeds, undergoing them again to a low temperature treatment.
The third generation of these plantsthe study authors assure, continued to show cold tolerancealthough these characteristics can be maintained for at least five generations.
Irrefutable proof
These findings led researchers to study epigenetic differences between the different varieties to find out the cause of their adaptation to cold. The team found that The tolerant variety at low temperatures had less Methylation of DNA, a chemical modification that regulates the activity of their genes.
In concrete, they observed that Cold stress reduced methylation Near the ACT1 gene (Acquired Cold Tolerance 1), which plays a crucial role in resistance to high temperatures.
Then they used fEpigenoma editing errors to modify the rice cultivated at normal temperatures. The results confirmed that this change Improves cold tolerance directly By increasing the expression of ACT1.
Later, re -established the original DNA methylation and rice plants have lost their ability to resist the cold. This, says the investigation team, dEmstra a direct relationship between epigenetic change and cold tolerance.
“Cold -induced changes in DNA methylation and ACT1 expression in response to cold are inherited in a stable way And they are associated with tolerance to the acquired cold, ”says the team – which admits, however, that it is necessary to continue to investigate these genetic mechanisms to completely understand their functioning.
In addition to confirming a Lamarckian heredity mechanism, the study offers practical applications.
The team proposed, for example, a new culture improvement strategy: expose plants to stress, identify beneficial epigenetic changes and then use precision editing to fix these characteristics.
“This approach could accelerate the development of resistant cultures climate change, addressing the food security challenges placed by global warming, ”says Cao XiaofengProfessor at the Institute of Genetics and Biology of the Development of CAS and the main author of the study.
