Using precision genetic engineering techniques, researchers at the Earlham Institute in Norwich have been able to turn tobacco plants into solar-powered factories for moth sex pheromones.

Critically, they showed how the production of these molecules can be efficiently managed so as not to hamper normal plant growth.

Pheromones are complex chemicals produced and released by an organism as a means of communication. They allow members of the same species to send signals, which includes letting others know that they are looking for love.

Farmers can hang pheromone dispersers among their crops to mimic signals from female insects, trapping or preventing males from finding a mate. Some of these molecules can be produced by chemical processes, but chemical synthesis is often expensive and creates toxic by-products.

Dr. Nicola Patron, who led this new research and leads the synthetic biology group at the Earlham Institute, is using cutting-edge science to get plants to produce these valuable natural products.

Synthetic biology applies engineering principles to the building blocks of life, DNA. By creating genetic modules with the instructions to build new molecules, Dr. Patron and his group can turn a plant like tobacco into a factory that only needs sunlight and water.

“Synthetic biology can allow us to engineer plants to make much more of something than they have already produced, or we can provide the genetic instructions that allow them to build new biological molecules, such as drugs or these pheromones,” Dr. Patron said.

In this latest work, the team worked with scientists from the Institute of Molecular and Cellular Biology of Plants in Valencia to engineer a species of tobacco, Nicotiana benthamiana, to produce moth sex pheromones. The same plant has already been engineered to produce antibodies against Ebola and even coronavirus-like particles for use in COVID vaccines.

The Group constructed new DNA sequences in the lab to mimic ringworm genes and introduced a few molecular switches to fine-tune their expression, effectively turning the manufacturing process on and off.

An important part of the new research was the ability to fine-tune the production of pheromones, because forcing plants to continually build these molecules has its downsides.

“When we increase efficiency, too much energy is diverted from normal growth and development,” Dr. Patron explained.

“The plants produce a lot of pheromones but they can’t get very big, which basically reduces the capacity of our production line. Our new research provides a way to regulate gene expression with much more subtlety.

In the lab, the team set about testing and refining the control of the genes responsible for producing the mixture of specific molecules that mimic the sex pheromones of moth species, including the orange belly button worm and the the cotton boll.

They showed that copper sulfate could be used to fine-tune gene activity, allowing them to control both the timing and level of gene expression. This is especially important because copper sulfate is a cheap and readily available compound already approved for use in agriculture.

They were even able to carefully control the production of different pheromone components, allowing them to modify the cocktail to better suit specific moth species.

“We have shown that we can control the expression levels of each gene relative to the others,” Dr. Patron said. “It allows us to control the ratio of products that are produced.”

“Getting this recipe right for moth pheromones is especially important because they are often a mixture of two or three molecules in specific ratios. Our collaborators in Spain are now extracting plant pheromones and testing them in dispensers to see how well they compare. to female butterflies.”

The team hopes their work will pave the way for the systematic use of plants to produce a wide range of valuable natural products.

“A major advantage of using plants is that it can be much more expensive to build complex molecules using chemical processes,” Dr Patron said. “Plants already produce an array of useful molecules, so we are able to use the latest techniques to adapt and refine existing machines.”

“In the future, we may see greenhouses filled with plant factories, providing a greener, cheaper and more sustainable way to make complex molecules.”

The research is published in the journal plant biotechnology.