Scientists from St Petersburg University and the Institute of Plant Molecular Biology in Strasbourg have analysed the genomes and transcriptomes of 631 plant species. They have found that there are many more naturally transgenic ones than they previously thought. The list of natural GMOs, in addition to tobacco, toadflax and sweet potato, now includes the closest relative of walnut, peanuts, cranberries, hops and tea.
If the genes of a contaminant, such as a bacterium or a fungus, enter the plant genome, such a plant is called transgenic. This mechanism is currently being actively used in agriculture to create genetically modified crops (GMOs), such as corn or wheat. This leads to their resistance to various pests: insects, fungi, viruses. However, the inventor of this unique tool is not a man. Scientists have spied it on agrobacteria – natural ‘genetic engineers’.
Research findings have been published in Plant Molecular Biology.
This group of bacteria have skilfully mastered the technique that geneticists call horizontal gene transfer: they can make small fragments of their DNA (T-DNA from a Ti plasmid) penetrate plant cells. This is responsible for tumorigenesis on roots or stems. The plant suffers from such a modification, but the bacterium does not: it feeds on substances that are produced in transgenic growths. This phenomenon is called genetic colonisation.
In fact, there are plants that have forever settled sections of DNA in their own genome. These sections used to belong to agrobacteria and they continue to transmit this information from generation to generation. It has long been known that these plants include some representatives of the genera Nicotiana (tobacco), Ipomea (bindweed plants, which also include batatas - sweet potato) and Linaria (medicinal plant toadflax).
The research was supported by a grant from the Russian Science Foundation No 16-16-10010.
The scientists from St Petersburg and Strasbourg managed to find out that this list is in fact much wider. T-DNA fragments of agrobacteria were found in the genetic material of representatives of the genera of such dicotyledons as: Eutrema; Arachis; Nissolia; Quillaja; Euphorbia; Parasponia; Trema; Humulus; Psidium; Eugenia; Juglans; Azadirachta; Silene; Dianthus; Vaccinium; Camellia; and Cuscuta. They were also detected in two monocotyledons: Dioscorea alata (yams - a plant similar to purple potatoes); and Musa acuminata (banana).
This includes, for example, the closest relatives of walnuts, peanuts, hops, cranberries, and tea which we drink every day. Some people are afraid of GMOs because they consider that transgenic plants are produced unnaturally. However, bacteria use exactly the same mechanisms as humans do when they get GMO commercial lines. Our research showed that this phenomenon is much more widespread, which means that mankind has constantly encountered GMOs throughout its history.
Tatiana Matveeva, the first author of the article, Doctor of Biology, Professor of St Petersburg University
Tatiana Matveeva noted that natural transgenic plants are good model objects for studying the effects of the spread of GMO crops. They can help to understand what will happen to transgenic plants created by humans, not only after 5, 10 or 15 years of their cultivation, but also after centuries and millennia. They can also help to understand the functions of T-DNA fragments that for an unknown reason have been preserved in the genomes of certain representatives of the flora. They might be responsible for some important traits that must be considered in selection.