Traditional pesticides can be harmful to the environment or other organisms, including humans. New solutions to pest management in agriculture are also going to be important if we are to feed a growing population with crops that may be under strain because of changes in the environment. A new project by the University of Helsinki and the French National Centre for Scientific Research (CNRS) is assessing how vaccines that interfere with strands of genetic material called RNA might be a good option for protecting plants in an environmentally friendly way.
"A new approach to plant protection involves vaccinating plants against pathogens with double-stranded RNA molecules that can be sprayed directly on the leaves," explained Dr. Minna Poranen of the Molecular and Integrative Biosciences Research Program at the University of Helsinki's Faculty of Biological and Environmental Sciences.
The vaccine uses a process called RNA interference, a natural system used by many organisms to defend against pathogens. It has been adapted for a variety of applications in the laboratory to manipulate gene expression levels. In this case, the vaccine initiates interference against RNA molecules that are used by pests. Those molecules are critical to the production of proteins essential to the pest, so when RNA interference halts the expression of those genes, the pest dies.
This mechanism would also be specific to the targets of certain RNA sequences that are only present in the pathogenic organism and so in theory, it would be harmless to other stuff. RNA is also sensitive to rapid degradation, so it would not start to accumulate in the environment.
The scientists made a technical breakthrough in this work. "The challenge in developing RNA-based vaccines to protect plants has involved the production of RNA molecules. Double-stranded RNA molecules have been produced through chemical synthesis, both as drug molecules and for research purposes, but such production methods are inefficient and expensive for plant protection," Poranen noted.
Poranen’s group has created a new method to make double-stranded RNA molecules as part of the Academy of Finland's Synthetic Biology Research Program. Typically in nature, RNA exists as a single-stranded molecule. With collaborators at CNRS, the scientists have concluded that bacterial cells can be used to produce RNA molecules that act as bacteriophages, which are viruses that kill bacteria. This strategy will make manufacturing those bacteriophages easier. It may be especially since they’ve also shown that RNA-based vaccines work when used against viral infections in plants. The vaccine strategy still has to be promoted for use, however.
"It's difficult to predict when the vaccine will be made available because no relevant legislation exists yet," Poranen added.