Slovenian researchers deploy new technologies to fight GMO stigma

The European Union has set ambitious goals as part of the green transition, which include a considerable reduction of pesticide use in farming. The established solution for pest resistance, if extermination with chemical agents is not possible, would be a genetically modified plant with a pest-resistant gene.

Since neither the legislation nor the current social climate are in favour of that, the Department of Agronomy at the Biotechnical Faculty, University of Ljubljana, began researching the Spray Induced Gene Silencing (SIGS) technology.

"With SIGS, the chemical content of sprays, already used by farmers now, is replaced with tiny RNA molecules. These molecules then stop or decelerate the expression of target genes in pests, which consequently kills them or inhibits their development and ability to infect the host plant," explains Taja Jeseničnik, a researcher at the Biotechnical Faculty, who works on the application of genetic methods to agriculturally important plants.

Environmentally friendly sprays

The main difference between SIGS and traditional GMOs is that by using sprays, the genome of plants and pests is not changed, only its expression is controlled. "The RNA molecules are very unstable and fall apart inside the cells, so integration into the genome is not possible," said Jeseničnik.

Because they are unstable, RNA molecules are very eco-friendly, since unlike synthetic chemical compounds, they do not last but disintegrate relatively quickly. This is exactly why fearing that people would consume them is redundant.

With SIGS, the effect of the spray can be very precisely targeted. "The RNA molecule, which is the active ingredient in sprays, is specific to one target gene that we choose," explained Jeseničnik. "This is why targets need to be chosen well, so that the chosen gene harms the adverse organism and not the other, beneficial organisms."

Researchers want the same spray to contain several RNA molecules for more target genes. This reduces the probability of mutations and development of resistance, since simultaneous mutations on several target points are unlikely. Moreover, having a larger number of targets means that the spray can be used for several pests at the same time, and have a broader application.

The path to application in farming

SIGS studies and the development of eco-friendly sprays are still in the early stages. There is only one such product on the market as of recently, which has been authorized for use in the USA. Scientists all over the world are currently actively searching potential target genes in pests to develop fungicides, insecticides, and herbicides. Among them are researchers from the Biotechnical Faculty, who are focusing on hops pests and are working together with a laboratory in Spain and the Slovenian Institute of Hop Research and Brewing in Žalec.

The introduction of these agents to the market is hindered mainly by price, since the production of RNA molecules remains extremely expensive. This is why development efforts must not focus only on molecules and their effects, but also on a faster and cheaper production of these molecules on a larger scale.

Until the new RNA sprays become financially interesting, the plant genome modification techniques used in pest protection that were discovered in the mid 1980s, will probably continue to evolve. At that time, scientists first realised that selected genes can be inserted directly into the plant and produce plants with the wanted traits faster, without time-consuming and expensive selective breeding.

Inserting foreign genes into organisms

Today, there are many different approaches to inserting genes into plants that are much faster than selective breeding, yet still not as simple as they might seem, says Jernej Jakše, a professor at the Ljubljana Biotechnical Faculty.

With monocot plants, the technique most often used is the gene gun, with involves cell nuclei being bombarded at high speeds with DNA particles. "With dicot plants, there is a specific bacterium which subdues the plants by inserting its genes into their cells and can be used in a laboratory to insert the desired genes."

One or a few genes are inserted, which compared to, say 32,000 genes that corn has, constitute a very small percentage. This results in a modification of traits, similar to the results of selective breeding but much faster, added Jakše.

Strict European regulation

One of the most successful examples of GMOs is soybeans, with three quarters of the world production being genetically modified. The case of soybeans, which have been on the market since 1996, proves that there are no harmful effects of GMOs on people's health," says Jakše.

Despite that, there is a lot of resistance to GMOs in society, which is reflected in European legislation. The EU has one of the strictest GMO regulations in the world, due to which GMOs today are used almost exclusively for animal feed. This is why RNA sprays could be one of the alternative solutions for achieving food security in the future.