Each year, plagues and vegetal illnesses evoque million of losses on world agriculture
Every year, plant pests and diseases cause losses running into millions in global agriculture. For decades, the main tool for combating them has been the use of chemical plant protection products. However, the emergence of resistance, increasing regulatory restrictions and the need to protect biodiversity are driving the development of more selective and sustainable alternatives. Among these, one technology is attracting enormous interest: biopesticides based on RNA interference (RNAi).
What is RNA interference (RNAi)?
Although the name may seem complex, the way it works is based on a simple principle. Rather than indiscriminately eliminating a pest using a chemical compound, RNAi makes it possible to ‘silence’ specific genes that are essential for the pest’s survival or its ability to cause disease. This is a natural mechanism present in virtually all eukaryotes, which regulates the expression of certain genes via small double-stranded RNA (dsRNA) molecules. When these molecules are taken up by the target organism, they block the production of essential proteins and reduce its ability to grow, feed or infect the plant.
This high specificity is one of the greatest advantages of RNAi over conventional pesticides. Whilst a chemical insecticide may also affect beneficial insects or other organisms in the ecosystem, an RNAi-based biopesticide can be designed to act solely on a specific species or even on a specific biological process. Furthermore, RNA molecules degrade naturally in the environment, reducing the persistence of residues and their environmental impact.
Another particularly interesting feature is its flexibility. Once a key gene in the target organism has been identified, it is possible to design new RNA molecules in a relatively short time, making it easier to respond quickly to new pests or to organisms that have developed resistance to traditional treatments.
SIGS: apply RNAi through spraying
Currently, this technology can be applied using two main strategies. The first involves developing plants capable of producing these RNA molecules internally, an effective approach but one associated with the use of genetically modified organisms. The second, known as Spray-Induced Gene Silencing (SIGS), simply involves spraying dsRNA onto plants, in a similar way to a conventional plant protection treatment. Once deposited on the plant’s surface, the molecules can be absorbed by the pest or pathogen and trigger the gene silencing mechanism. This strategy offers great versatility, as it can be used on different crops, allows the timing of application to be determined, and avoids the need to genetically modify the plant.
Interest in this approach has grown rapidly in recent years and has already led to significant regulatory advances. In 2023, the US Environmental Protection Agency (EPA) approved Ledprona, the first sprayable dsRNA-based biopesticide for the control of the Colorado potato beetle (Leptinotarsa decemlineata), marking a milestone in the market launch of this technology. As with any emerging technology, there are still challenges that need to be resolved before it can be widely adopted. One of the main challenges is the stability of RNA, as these molecules can degrade rapidly due to ultraviolet radiation, rain, temperature or certain enzymes present both in the environment and in the target organisms themselves. It is also essential to select the correct gene to target, ensuring high efficacy and minimising any potential effects on non-target organisms. Consequently, much of the current research focuses on developing new formulations capable of protecting dsRNA using nanoparticles, liposomes or biological vesicles, as well as on optimising its large-scale production and advancing regulatory and environmental assessment processes.
The SUPERA project: how CARTIF is developing new RNAi-based solutions
In this context, CARTIF is actively involved in developing these new strategies through the SUPERA project (Sustainable plant health through RNAi to reduce the impact of diseases on agriculture and forests), coordinated by the University of Valladolid in collaboration with the CSIC and IDAI Nature. The aim of the project has been to develop innovative RNAi-based solutions to combat diseases caused by fungi and oomycetes that affect both agricultural crops and forest species. During the project, essential genes were identified in highly significant pathogens, such as Fusarium and Phytophthora, and specific dsRNA molecules were designed to reduce the expression of these genes. At the same time, production processes using bacterial fermentation were optimised, and encapsulation strategies were developed to improve the stability of the molecules and facilitate their application via foliar and root treatments, bringing this technology closer to future real-world applications in agriculture. The results obtained demonstrate that RNAi has evolved from being merely a tool for basic research into a technological platform with enormous potential for developing a new generation of biopesticides that are more precise, sustainable and environmentally friendly. Although there are still scientific and regulatory challenges to be overcome, all the signs suggest that, over the coming years, this technology will play an increasingly important role in integrated crop protection strategies, contributing to a more efficient and resilient agricultural sector that is aligned with the sustainability goals demanded by society.
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