“Effective DSRNAS” fighter -cucumber -mosaic virus in tests

Researchers at Martin Luther University Halle-Wittenberg (MLU) have developed RNA-based active ingredients that reliably protect plants from the cucumber mosaic virus (CMV), the most common virus in agriculture and horticulture. Developed to combat the virus by leading the natural defenses of the plant in the right direction. The team's laboratory experiments showed that 80–100% of the plants treated survived the CMV infection with a high virus load.

Research manager Sven-Erik Behrens, PhD, at the Institute for Biochemistry and Biotechnology at the MLU and colleagues, reported their results in Nucleic acid researchIn a paper entitled “A new measure of RNA-based crop protection DSRNAS made from functionally characterized Sirnas, which are highly effective against cucumber mosaic virus”. In his work, the team came to the conclusion: “Overall, the results of this study significantly expand the potential for more efficient use of RNA in biological harvest protection”.

Virus-induced plant diseases remain a major problem in agriculture that “recently exacerbated by global trade and climate change,” wrote the authors. Pesticides represent the most common methods of controlling virus infections, but such active ingredients cannot have specific effects on other organisms and can be harmful to humans. “Urgently needed alternative crop protection methods should not only be environmentally friendly, but also specific, i.e. only against a specific target pathogen and adaptable to the development of the pathogen,” said the team. “The RNA-mediated harvest protection is increasingly becoming a practical alternative to agrochemicals that threaten the biological diversity and human health.”

The cucumber mosaic virus is a particularly devastating virus for plants. Around 90 types of aphids transmit the virus, which affects more than 1,200 plant species, including numerous agricultural plants such as pumpkin, cucumber, cereals as well as medical and aromatic plants. Infected plants can easily be identified by a characteristic mosaic pattern on their leaves. As soon as the plants are infected, they cannot thrive and their fruits cannot be sold. There are currently no approved agents against CMV.

If a virus infects a plant, it uses the cells of the plant as a host. The virus multiplied by its genetic material in the form of RNA molecules in the plant cells. As soon as these foreign RNA molecules have been injected, they trigger an initial reaction from the facility of the system. Special enzyme scissors recognize and cut the viral RNA molecules. This process creates small disturbing RNAS (Sirnas) that spread throughout the work and trigger a second step of the immune response. The Sirna molecules bind to special protein complexes and lead them to the RNA molecules of the virus. Once there, the proteins begin to reduce the harmful RNA molecules of the virus by converting them into harmless, degradable fragments.

“In general, this defense process is not very effective,” said Behrens. “A viral infection produces many different Sirna molecules, but only a few have a protective effect.” Thanks to their newly registered work, the team developed a method to identify functionally effective Sirna molecules, which were referred to as ESISRNAS and are very efficient. “With an in -vitro screen that reliably identified Esirnas from Sirna pools, we identified Essirnas against cucumber mosaic virus …”, the authors said.

They were able to combine several of these Esirna molecules into efficient double-stranded RNA molecules (EDSRNAS) that could be applied to plants. These EDSRNAS act as a package, which is divided into a large number of highly effective Sirna molecules shortly after entering the plant cells, which can attack the virus at various points, which can significantly increase the protective effect. “RNA viruses like the cucumber mosaic virus are dangerous because they can develop quickly,” said Behrens. “In addition, the genetic material of this virus consists of three separate parts, which can mess and further increase the likelihood of new mutations.

The team carried out numerous laboratory experiments in the model system NikoTania Benthamiana And was able to show that EDSRNA-based active ingredients were reliably protected against cucumber mosaic virus. “The plants in our experiments were infected with a very high virus load: all of our untreated plants died,” said Behrens. In contrast, 80–100% of the plants treated survived. “… Optimal protection was reached with newly designed multivalents 'effective Dsrnas' (Edsrnas), which contain the sequences of several eating nases and preferably processed into these ESISRAS,” explained the authors. “The Esirna components can attack one or more target RRAS at different points, be active in different silent switch complexes and cross against various viral variants.

The team has also optimized the screening process on efficient synas and can adjust the process to target new viral mutations within two to four weeks. “Time is an important factor: If a new virus variant arises, we can change the active agent very quickly,” said Behrens. The approach can also be applied to other pathogens and pests. “The success of our approach, ENA screen, followed by EdsRNA design from the identified ESGNAS, promises a similar success for other plant pathogenic, most of which have less plasticity than CMV,” said the authors.

So far, the substances have been given manually in the laboratory either by injection or by rubbing into the plant leaves. The team works with the pharmacist and pharmaceutical supply specialist Karsten Mäder, PhD, a professor at the MLU, to use the substances that are more durable and easier to use on RNA-based substances. For example, they could be sprayed.

At the same time, the researchers are planning field trials to test the RNA-based substances under real conditions. “It will now be important to further test and improve food in combination with suitable formulations in agricultural applications, ie, greenhouse or field tests,” the investigators wrote in their report. They also talk to companies about future industrial production. In addition, potential products for new harvest protection products still have to go through an approval process, so it takes some time for a product to combat the cucumber mosaic virus. “However, we are convinced that our approach is feasible.