Researchers Develop New Modular Vaccination Kit For Plant Protection

The new modular vaccination kit for plant protection is simple, fast, and yet flexible. This could become significantly easier to vaccinate plants against viruses in the future. Researchers at Martin Luther University Halle-Wittenberg (MLU), the Leibniz Institute of Plant Biochemistry (IPB) and also the National Research Council in Italy (CNR) have developed a new method for plant protection purpose. It enables rapid identification as well as the production of precisely tailored substances that combat different pathogens. The scientists discuss their work in the next edition of the journal “Nucleic Acids Research.”

The new method for plant protection is based on a molecular defense program of plants that is triggered, for example, by viral infections. Plant’s cells serve as a host to multiply the virus. This results in the creation of viral ribonucleic acid molecules (RNAs) during a virus attack. Plants can detect as well as cut up these molecules using special enzyme scissors. “small interfering RNAs” (siRNAs) are produced as a part of this process which spread throughout the plant and may initiate the second stage of defense for the plant. Here, the small interfering RNA molecules attach themselves to so-called Argonaute protein complexes and lead these to the virus RNAs. In the best-case, it can be dismantled and broken down into many harmless compounds. Professor Sven-Erik Behrens of MLU’s Institute of Biochemistry and Biotechnology said that by implementing this two-stage process, the plant is actually trying to protect itself from the virus both at the site of the infection and throughout its structure.

The two-stage process is not particularly efficient, however, as the biochemist explains that when a viral infection occurs, there are lots of different siRNA molecules produced. In fact, very few of them have a protective effect among these molecules. The majority of the molecules simply saturate the Argonaute complexes, rendering them inactive. Behrens’ research team has discovered a novel way of the plant protection to identify the few effective antiviral small interfering RNAs molecules for different viruses and harness them as plant vaccines. The researchers have developed a screening process based on plant cell extracts, which is being used instead of lengthy and complex breeding efforts. In order to qualify as potential vaccines, the small interfering RNAs molecules must have two key properties: Primarily, they have to bind strongly to the Argonaute complexes and Secondly, they will have to lead these proteins to sites of the viral RNAs that are accessible for Argonaute-mediated degradation.

Now, the research team is working on vaccinations for plant protection has already been able to prove the effectiveness of their new vaccination method in the laboratory. In order to achieve this, two groups of the tobacco plant N. benthamiana were infected with a model virus which attacks tomatoes and tobacco. Before being infected with the model virus, one group was vaccinated with highly efficient small interfering RNAs molecules that the researchers had identified using the new method. The other group of organisms did not receive any treatment. The effects of these were very striking where after six weeks of the treated where 90% of the vaccinated or treated plants did not show any signs of infection, but all the untreated plants had been killed by the virus.

The MLU research team’s method follows the modular principle where if the pathogen changes or the plant has to be protected against another virus. This established screening process enables suitable RNA molecules to fight against the respective pathogen to be identified very quickly, which means we can be very flexible when it comes to combatting new pests said, Behrens. The patent application has been already filed for the method of Plant Protection Vaccination Kit.

The research team hopes to continue exploring and improving their method in the future. It still unclear how long a vaccination treatment will last in different species and also whether drug depots can be created on plants. Further new studies will clarify how vaccines can be produced in larger quantities. Studies will also give answers on how these vaccines can be applied to or how can it be absorbed by the plants. A spray which can be applied in greenhouses is conceivable according to Behrens. Its like tomato growers have to contend with whiteflies, for example, and these can transfer viruses from one plant to another very quickly. Till now, all pesticides have been used to kill off the insects. The new MLU development of plant vaccination kit could prove to be an alternative which is much gentler both to the insects as well as to the environment.