RNA-based substances open up new avenue to combat a widespread plant virus

The new RNA-based active agents protect plants against cucumber mosaic virus (CMV), the most common virus in agriculture and horticulture. They were developed by researchers from Martin Luther University Halle-Vetanberg (Mlu).

Active ingredients have a broad spectrum effect; A series of RNA molecules support the immune system of the plant in dealing with the virus. In laboratory experiments, 80 to 100% treated plants survived infection with a high viral load, as Team report In Nucleic acid research,

His paper has been chosen as a “success article” by the journal. Researchers are now working on transferring thoughts from the laboratory to behavior.

Cucumber mosaic virus is a particularly devastating virus for crops. About 90 species of aphids transmit the virus, which affects more than 1,200 plant species. These include many agricultural crops such as squash, cucumbers, grains and medicinal and aromatic plants. Infected plants are easily identified by a characteristic mosaic pattern on their leaves.

Once infected, the plants fail to flourish and their fruits cannot be sold. To date, there are no approved agents against CMV. However, new work by researchers of MLU can provide a long -term solution. The original idea is to fight the virus by directing the natural defense of the plant in the right direction.

When a virus infects a plant, it uses plant cells as a host. Ribonucleic acid (RNA) multiplies in the cells of the virus plant through its genetic material in the form of molecules. Once the injection, these foreign RNA molecules trigger the initial response from the immune system of the plant. Special enzyme scissors recognize and cut viral RNA molecules.

The process produces small intervention RNAs, which spreads throughout the plant and triggers the second stage of the immune response. SIRNA molecules bind to special protein complexes and guide them to RNA molecules of the virus. Once, the harmful RNA of the protein virus begins to break down by converting molecules into harmless, derogatory pieces.

“In general, this defense process is not very effective. A viral infection produces many different SiRNA molecules, but only a few have a protective effect,” Mlu is called a biochemistry and biotechnology institute professor Swen-Arich-Beharan. His team has developed a method to identify SiRNA molecules which are highly efficient in this process.

In another important step, they were now able to combine many of these SiRNA molecules in so-called efficient double-stranded RNA molecules (EDSRNAS), which are particularly suitable for use in plants. These edsrnas act as a type of “package” that breaks into sirnas immediately after entering the plant cells. In this way, a large number of highly effective SiRNA molecules can have a protective, antiviral effect on the spot.

The team conducted several laboratory experiments on model plant Nicotania Bentamiana and was able to show that EDSRNA-based active agents firmly protect from cucumber mosaic virus.

“Plants were infected with a lot of viral load in our experiments: all our untreated plants died,” describes Behrence.

In contrast, 80 to 100% treated plants survived. EDSRNA is another special advantage of agents: When the package is broken, a group of efficient SiRNA molecules is generated that attacks the virus, especially on various sites. It enhances quite a quite protective effect.

“RNA viruses such as cucumber mosaic viruses are dangerous as they can grow rapidly. In addition, the genetic material of this virus is made of three different parts, which can be mixed, which increases the chances of new mutation. To get maximum protection against the virus, our active materials target various parts of the genome.”

The team has also adapted the screening process for skilled siRNAs and can adapt the process of targeting new viral mutations within two to four weeks.

“Time is an important factor: When a new virus variant emerges, we can modify the active agent very quickly,” describes the Behrence. The approach can also be applied to other pathogens and insects.

By now, substances have been manually administered in the laboratory, either by injection or rubbing them into plant leaves. The team is working with pharmacist and drug delivery specialist Professor Korston Meder at MLU to make RNA-based substances more durable and more durable and easy to apply to plants.

For example, they can be sprayed. At the same time, researchers are planning field tests to test RNA-based substances under real circumstances. And they are talking to companies about future industrial production.

In addition, potential new crop protection products still have to undergo an approval process, so it will be some time before a product to combat the cucumber mosaic virus.

“However, we are convinced that our approach is possible. The first crop protection product with the RNA-based active ingredient was recently approved in the US,” says Behrence.