2023-10-20 14:05:00
This Thursday, October 19, 2023, a team of Perpignan researchers published a study demonstrating that lianas and trees in the Massane forest had transmitted fragments of DNA to each other simply because of their physical proximity. A discovery which tends to prove that beyond heredity, the ecosystem can also influence genetic heritage.
The thousand-year-old Massane forest, classified as a nature reserve since 1973, has not finished revealing its secrets. Perched on the heights of Argelès, this site, where nature has evolved freely since the 18th century, lists no less than 10,000 species of fauna, flora and mushrooms. It is because of this abundant biodiversity that scientists from the Plant Genome and Development laboratory at the University of Perpignan chose to carry out a study there on the transfer of genetic material between species outside of reproduction.
“Through reproduction, genes are transmitted from parents to descendants. This is what we call vertical transfers, resituates the CNRS researcher attached to the University of Perpignan Moaine El Baidouri, who coordinated the study. But we have known for around ten years that distinct animal or plant species, which have nothing to do with each other, can also exchange genes or other elements of DNA outside of this framework. These are called horizontal transfers. We still do not know what mechanisms make these exchanges possible.”
The vine had alerted them
These transfers of genetic material can allow species to adapt. A bit like an exchange of technology between civilizations. The genes “stolen” via horizontal transfers are comparable to tools that can be used immediately without the need to develop them. However, until now, the scientific community had mainly identified horizontal transfers between hosts and parasites (viruses, bacteria, fungi, etc.). For example, it now seems certain that the emergence of mammals (and therefore humans) is linked to a horizontal transfer. The ability to produce placenta actually comes from a gene of viral origin. “But in this kind of case, we have very close contact. The viruses or fungi penetrate inside the tissues”points out Moaine El Baidouri.
In 2014, the Perpignan genomicist realized that horizontal transfers of genetic material might occur with less close contact, following having demonstrated such exchanges between the vine and several trees (palm, lemon, etc.). He then formulated the hypothesis that simple physical contact might allow exchange between lianas, such as vines, and trees. It is in order to verify this hypothesis that the study which has just been published in the American scientific journal PLOS Genetics was launched.
Unexploited since the 18th century, the Massane forest presents abundant biodiversity. Nicolas Parent – Nicolas Parent
The ecosystem leaves traces in the DNA
“We sampled several species of trees and lianas from the Massane forest and deciphered their genomes in order to look for transfers and check if our hypothesis was true, summarizes Moaine El Baidouri. This is how we discovered horizontal transfers between lianas and trees. Particularly between ivy, ash and oak. The study also suggests that proximity, simple contact between lianas and trees, is enough to cause these exchanges.”
We are not only the result of what we inherited from our parents, but also the fruit of our interactions
Made as part of a collaboration with the nature reserve, this discovery updates the theory of evolution. “It puts the ecosystem back at the center by showing that interactions between species within the same environment result in an enrichment of the genomes of each of the species concerned, continues the DNA specialist. If species had evolved separately, they would not be what they are today. Each contains traces of its past interactions in the form of genetic material. We are not only the result of what we inherited from our parents, but also the fruit of our interactions.”
However, the study also poses many new questions. In the cases examined at La Massane, for example, scientists do not yet understand the exact usefulness of transfers of genetic material for each species concerned. For the moment, they are not even sure that they really have a use… Moreover, the precise mechanism of these horizontal transfers also remains mysterious. Scientists assume that viruses, insects or bacteria might play a role as vectors. But they don’t have proof yet. Another hypothesis to verify.
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