UK institute trials genome-edited wheat to reduce carcinogenic acrylamide levels in bread

03 Sep 2021 --- Field trials of CRISPR-edited wheat are underway at Rothamsted Research, an unprecedented study for both the UK and mainland Europe, which have stringent GM regulation. The UK’s Department for Environment Food & Rural Affairs (Defra) has greenlighted the trials to reduce high levels of acrylamide in bread – a carcinogenic processing contaminant that arises when bread containing asparagine is baked or toasted.

FoodIngredientsFirst speaks to project leader Professor Nigel Halford of Rothamsted Research, who is working to produce ultra-low asparagine, non-GM wheat using genome editing (GE) for safer and healthier bakery products. 

“We believe that asparagine levels can be reduced substantially in wheat without compromising grain quality. This would benefit consumers by reducing their exposure to acrylamide from their diet, and food businesses by enabling them to comply with regulations on the presence of acrylamide in their products,” explains Halford. 

The five-year study project is unveiled as EU regulation surrounding high levels of the disconcerting contaminant tightens. 

Acrylamide content has been found in many foods that are fried, baked, roasted or toasted, including crisps and other snacks, chips, roast potatoes and coffee.The problem with acrylamide
Acrylamide has been found to cause cancer in rodents, although epidemiological studies linking the substance to cancer in humans have been “mixed,” Halford adds. 

Nevertheless, acrylamide has been on the food industry’s and regulatory bodies’ radar since it was discovered in 2002. 

In addition to bakery products, acrylamide content has been found in many foods that are fried, baked, roasted or toasted, including crisps and other snacks, chips, roast potatoes and coffee.

“Current regulations on acrylamide include ‘benchmark levels’ for its concentration in different food types and require food businesses to monitor their products for its presence.”

Halford stresses that it is “likely” these regulations will be strengthened, with the EU moving towards the introduction of maximum levels. 

In this case, it would be illegal to sell a food product above the maximum level, he warns and other regulatory authorities would likely follow suit. 

Starting in the field
With the long-term goal of making safer bread, this initial project aims to assess the performance of the wheat plants in the field and to measure the concentration of asparagine in the grain produced under field conditions. 

During development in the lab, researchers “knocked out” the asparagine synthetase gene, TaASN2.

Genome-edited and genetically modified crops are regulated the same way in the EU, which Halford believes is not founded on science.Asparagine concentrations in the grain of the edited plants were substantially reduced compared with un-edited plants, with one line showing a more than 90 percent reduction, according to project scientist Sarah Raffan.

“This new trial will now measure the amount of asparagine in the grain of the same wheat when grown in the field, and assess other aspects of the wheat’s performance, such as yield and protein content.”

Under the terms of the agreement, GE wheat in the trials cannot be consumed and must be destroyed after analysis, says Halford. 

“Safety tests could come much later, if the wheat comes through the trials successfully, and there is a possibility that it could be commercialized.”

Five years in the making
The plan is for a project of up to five years, ending in 2026, with plants being sown in September to October each year and harvested the following September.

The edited plants will be grown alongside wheat in which asparagine synthesis has been affected using the “old-fashioned” method of chemically-induced mutation.

Chemical mutagenesis has been widely used in plant breeding since the mid-20th century and is therefore exempt from GM regulation.  

With modern genomics, the researchers can identify individuals within a mutant wheat population with mutations in the right gene. However, it is not targetable in the way that CRISPR is and results in random mutations throughout the genome, explains Halford. 

These have to be “stacked” by crossing different individuals so that all of the target genes are mutated, so it is a slower process than CRISPR and might have been unfeasible altogether if wheat had more copies of the target gene. 

The GE wheat in this round of trials will not be able to be consumed.Editing a plant with CRISPR
CRISPR makes small changes to a target gene, in this case, to knock that gene out so that a functional protein is no longer made from it. 

The process initially involves genetic modification to introduce genes required for the CRISPR process into the plant.

Once the edit has been made, the GM part can be removed from the plants by conventional plant breeding methods over a few generations. 

“We can do this by self-pollinating the plants and looking for plants in the next generation that have the edits but not the GM components. That is already in progress, and we have some lines that have already lost 2 of the 3 GM components we used,” says Halford. 

GM Regulation 
Halford further notes that the Court of Justice of the European Union in 2018 ruled that GE crops should be regulated like GM crops. 

“There is no scientific basis for the current situation, or, for example, regulating GE crops more stringently than crops produced by chemical mutagenesis.”

“[GE crops] should not be considered the same as GM because by the end of the process, they do not contain any transgenes or foreign DNA,” explains Halford.

He adds that GM plants have been heavily regulated in the EU since the 1990s, and businesses wanting to market them for food and feed use or for cultivation have to get permission (a Part C consent) from the European Commission. 

“That is difficult to do for food and feed use and just about impossible for cultivation. The EU does import millions of metric tons of GM soybean, maize, cotton, and so on, every year, mostly for animal feed, but no one even tries to get permission to cultivate GM crops in the EU any more.”

A healthier future?
With tight EU laws, Brexit may offer some new regulatory opportunities. 

So far, EU law has rolled over into UK law following Brexit, says Halford. But there has been a consultation on genome editing and there is talk of the law being changed in the UK, he affirms. 

Researchers at Rothamsted Research hope that the current UK government consultation on this issue will lead to new legislation in the UK, allowing genome-edited food products, carefully regulated, to be available to consumers. 

Funding is in place for the first year of the project, and additional support is being sought for the subsequent years.

By Missy Green