A plan for using viruses to improve crop yield

Humans, livestock and pets benefit from virus-based vaccines and gene therapies, but crops do not. This paradox is highlighted by an international research group led by the Institute of Molecular and Cellular Biology of Plants (IBMCP) of the Spanish National Research Council (CSIC) in an article published in Nature reviews bioengineering.

The study proposes a plan to use attenuated viruses to increase the performance of crops and make them more resilient to extreme and changing climate conditions or to produce nutritional supplements for better human nutrition. According to the authors, this is a more efficient and sustainable alternative to agrochemicals and faster than traditional breeding methods.

The article is part of the “Future of Food” collection, which includes the journals Nature Reviews Bioengineering And Natural food Current articles on technical progress and the possibilities of technical food technologies.

“Our article presents thought-provoking viewpoints and confronts readers with paradoxical situations,” says Fabio Pasin, CSIC researcher at IBMCP and lead author of the study. The authors propose that viral vectors based on attenuated viruses that are harmless to plants could be used to introduce specific genes into crops, thus improving their agronomic properties. These viral vectors could be used to induce plant flowering and accelerate harvests, develop improved crop varieties, modify plant architecture to facilitate mechanization, improve drought tolerance or produce metabolites beneficial to human health, among other things.

The use of attenuated viruses may be the best way to achieve the desired plant traits.

“Imagine you're using a computer that's not connected to the Internet, and every time you need a software update you have to buy a new computer,” says Dr. Pasin. “Our idea is to use a virus like a USB stick: you plug it into the computer, install updates, and keep using it.”

“These vectors can be used for precise genome editing through CRISPR-Cas components to achieve heritable improvements in agronomic traits such as grain length and weight in wheat or fruit color in tomatoes. In addition, viral vector applications enable transient improvements and, due to their rapid development and validation, offer an attractive alternative to the use of agrochemicals for more efficient and sustainable agricultural production systems,” says the CSIC researcher.

People, livestock and pets, but no plants

Despite these advantages, the authors point out some paradoxes: the administration of recombinant viruses to humans (e.g. against COVID-19) and the vaccination of animals are considered safe, yet no agricultural use has been registered. Humans and pets can benefit from gene therapies based on recombinant viruses, but crops cannot.

Recombinant viruses can be released into the environment to immunise wild animals such as foxes, raccoons or coyotes, thus bringing rabies under control in Europe and the USA. However, their use in agriculture is still not approved, even in very confined environments.

What is needed for implementation?

Given its benefits, could this new technology also be used in crops? One obstacle is regulatory issues. Scientists see a certain gap in a transient delivery approach that would allow the use of viral vectors to improve crops immediately.

“It is a novel product, similar to an agrochemical. However, since it is a biological product, there is currently nothing similar on the market for agricultural use. So there are no precedents and a thorough analysis by the authorities would be necessary,” explains Dr. Pasin.

This process could be accelerated by using recombinant viruses, implementing methods to ensure biocontainment, and giving priority to crops used as animal feed, textile fibers, biofuels or ornamental purposes, he argues.

In plants, viral vector technology is in an advanced research phase and its effectiveness has been demonstrated under experimental conditions. At CSIC, researchers are optimizing technological platforms to accelerate the development and validation of agricultural applications based on viral vectors by implementing synthetic biology approaches compatible with future industrial-scale production. In addition, they are exploring the use of viral vectors to improve the agronomic characteristics of crops such as tomatoes.