— It is known that genetic insertions, the dangers of which GMO opponents have long talked about, are also present in natural products. When did scientists first discover this?
— The first article devoted to this topic by scientists from the University of Washington was published in 1983. They found that Nicotiana glauca tobacco contains sequences very similar to those in Agrobacterium. It is now actively used as a tool for transgenic plant production.
For a long time it was unclear how common this phenomenon was. And in 2012 our article was published. We searched for Agrobacterium sequences in more than one hundred dicotyledon genomes. As a result, we found such sequences in representatives of the genus Linaria (Flax is a genus of herbaceous annual and perennial plants of the Banana family). In late 2015, scientists discovered that sweet potatoes are naturally GMO.
Tobacco, flaxseed and sweet potatoes were actively used by people. That’s why our research attracted attention. And this was a strong argument in the debate with opponents of GMOs that genetic engineers are invading nature and that we are eating plants obtained in an unknown way.
— What are these agrobacteria whose genomes are found in plants?
—This is a soil bacterium that is a close relative of the microorganisms that form nitrogen-fixing root nodules on legume plants. But unlike them, Agrobacterium causes diseases such as crown galls and hairy roots when it infects plants. These bacteria cause great problems in agriculture because they cause crop yields to decrease. So people started studying them. It turns out that when a bacterium infects a plant, it manages to insert a piece of its DNA there. As a result, this DNA begins to work in plants as if it were a native plant gene.
It is now clear that there are, in fact, many natural GMOs. And traces of agrobacterial infection in the genomes include about 7% of dicotyledonous plants. And dicotyledons include vegetables and fruits. Moreover, Natural GMOs include tea, peanuts, wasabi, cranberries, blueberries, cranberries, walnut relatives, dates, etc. It is found in foods.
— So if we drink tea every day, does that mean we consume GMOs every day?
– Yes. Moreover, this number may increase in the future after more plant genomes are studied. We are talking about 7% of plants that contain Agrobacterium genes in their genomes. However, there are also viruses that can, for example, infect plants, leave their mark on the genome, and then be passed on from generation to generation. This is still a somewhat researched area and interesting discoveries can be expected here in the near future as well.
— Are genes in bacteria not just “silent” but also working in plants?
— Yes, this is the subject of our last article about night tobacco. We even identified the product of one of these genes. This is agrosinopine synthase, it synthesizes small molecules – opines. It is believed that these molecules attract certain microorganisms, meaning that thanks to this gene, the plant can independently form its own microbial community.
It’s hard to say why he did this; This is the next step in our research. But there are two versions. According to the first, if, for example, these microbes can fix atmospheric nitrogen, this may be necessary to obtain some useful substances from them. Then the soil will be rich in nitrogen needed by the plant. The second version is that the plant is able to attract some bacteria and thereby repel other pathogenic bacteria.
— How can we describe the process by which the Agrobacterium genome integrates into a plant?
– This is a complex mechanism. The bacterium has a plasmid (circular DNA molecule) containing T-DNA, from the English word transferred – transferred. One strand of this DNA is cut and the remaining sequence is completed along the other strand, so that the plasmid does not lose its original shape. This single-stranded chain is maintained by proteins that are products of genes from the same plasmid but outside the T-DNA. They help cut this single chain and surround it on all sides, directing it from the bacterial cell to the plant cell.
Then, once it enters the nucleus, this T-DNA must integrate into the host chromosome. And in this process, both proteins of agrobacterial origin and some plant proteins are involved.
— Do genetic engineers repeat this process when creating artificial GMOs?
– Yes. They detected this mechanism in bacteria.
— Opponents of GMOs believe that the danger of such plants lies in the possibility of the bacterial genome integrating into human DNA. For example, can this occur when eating sweet potatoes?
“If that were the case, we would be green and photosynthesizing a long time ago.” In fact, there is a piece of DNA in the sweet potato that was once bacterial. But this is only a small part of the DNA, much more is indigenous.
Many studies have been conducted to examine the possibility of inserting transgenes into the genome of mice, chickens and other animals. The transgenes were shown not to integrate anywhere. They even did this experiment on cows, but nothing was found in the milk.
If we are talking about horizontal gene transfer (the process of transferring genetic material to non-descendants), this is a common phenomenon to which all organisms are susceptible. It has been shown that in some invertebrates, approximately 5% of genes are obtained as a result of horizontal transfer.
— In addition to methods of creating GMOs using plasmids, newer genome editing technologies are also available. How do these editors work?
“To do this, they use proteins that can programmatically cut DNA. Systems that then restore DNA integrity in the cell eliminate these cuts, but do so incorrectly. In this way, point mutations can be created deliberately.
This entire structure, which produces an enzyme that can cut DNA, is built on the same genetic engineering principles. This structure can be delivered to the plant using Agrobacterium.
— If GMOs exist in nature, from your point of view, should there be a label on the products indicating that genes have been artificially added?
— I think artificial GMOs should be labeled. If we try to hide even something harmless, it causes fear and fear in people. Being afraid of something unfamiliar is a common human reaction.
I think marking is also necessary for the edited genome. For example, I, as a scientist who received a genome-edited line, should be able to present it to people, be proud of my work, and not hide it. Another thing is that if this is not done, no one will be able to detect the edited genome using existing methods.
— So, if you edit the genome using the Agrobacterium plasmid, would it be possible to detect artificial GMOs?
“It all depends on whether traces of the agrobacterium remain in the genome.” If we obtain a transgenic plant using an agrobacterium, we find a piece of foreign DNA in it. Where this piece comes from is the next question.
— Can we be sure that modern methods can detect any transgene in plants?
— We now have a common knowledge base of all known transgenic lines allowed to be grown in the world. So we understand which transgenes make sense to look for in the genome.
If you imagine a bad guy inserting a foreign gene into the genome of, say, a tomato, this is unlikely. This is a labor-intensive and highly skilled job that cannot be done at home or in underground laboratories.
— There is a law in Russia that prohibits the cultivation of GMOs, but does not prohibit their use. Do you think this law is good?
— It would be better if our producers had the opportunity to grow normal GMO lines. In fact, this law now benefits foreign manufacturers. Since transgenic plants are more productive and more resistant to negative environmental factors, it is more profitable for farmers to grow them.
From my point of view, the circulation of GMOs in the country needs to be regulated correctly so that we can introduce and use our own lines and developments. Moreover, even though they are natural, we still eat GMO products every day.