FAQs: Planned field trial of high-iron wheat

Researchers at the John Innes Centre have applied to Defra to grow a small-scale field experiment (50 m2) of genetically modified (GM) wheat in 2022 – 2024, following previous successful field trials.

Here we explain why this field trial is important and how it may contribute to sustainable food production in the future.

Why high-iron wheat?

Wheat is an important staple crop, and the main ingredient of bread, pasta, cakes, biscuits and breakfast cereals. It’s a good source of carbohydrates and protein, and wheat grain is rich in mineral micro-nutrients such as iron. However, in the process of milling most of the iron is lost when the germ and bran are removed.

Deficiencies in the mineral micronutrients iron and zinc are a global health issue. White flour usually contains between 5 and 8 milligram (mg) of iron per kilogram (kg), which is low for human nutrition. Therefore, in the UK and many other countries in the world, iron powder or iron salts are added to flour and breakfast cereals 1.

In the UK, there is a legal requirement to bring the iron concentration of milled flour up to 16.5 mg per kg 2. You will find ‘iron’ as an ingredient on many wheat products, such as packs of flour, sandwiches and confectionery.

Using genetic modification researchers at the John Innes Centre have developed a wheat line that contains 20 mg per kg iron in milled white flour 3,4 when plants are grown in greenhouse conditions. In principle with our high-iron wheat there would no longer be a need to add iron as an extra ingredient to wheat flour.

It has also been shown that the iron in this white flour is bioavailable 3,5, meaning that the iron is in a form that can be absorbed and used by the human body. This suggests that food products made from the biofortified flour could contribute to improved iron nutrition.

The video below was produced for a previous successful trials of high iron wheat which used wheat genes to increase the iron content of the endosperm of the grain. The video explains how the process works in general terms, but does not include the specifics of the proposed trial.

What is biofortification?

Increasing the nutritional quality of crops is known as biofortification. Using plant breeding we can increase the total amount of important nutrients in food crops to alleviating micronutrient deficiencies in people. It can be a more sustainable alternative to adding vitamins and minerals to food products.

Biofortified crops are currently being implemented in several countries to combat nutrient deficiencies, so called ‘hidden hunger’, focusing on vitamin A, zinc, iron and selenium.

It would be good to add high-iron wheat to the range of biofortified crops, but so far it has not been possible to increase iron in wheat grain to the levels required using conventional breeding.

The iron content of staple crops such as wheat has been difficult to improve using conventional breeding, and as a result many wheat products for human consumption have to be artificially fortified with iron.

How has the wheat been Genetically Modified?

The genetic material of wheat has been changed using genetic modification techniques to increase the iron and zinc in the wheat grain.

In the field trials in 2019 and 2021, the effect of one inserted piece of DNA (gene) was tested, in the proposed field trials another piece of DNA is added to that.

The previous trial tested a piece of DNA that encodes an iron transporter protein (which is called VIT2 for Vacuolar Iron Transporter 2) which was isolated from the wheat genome, and placed behind a regulatory piece of DNA, also from wheat 3. This was then inserted back into the wheat genome.

The regulatory sequence ‘tells’ the wheat plant when and where to produce the iron transporter. In this case, an extra amount of iron transporter is made during grain development only and is restricted to the so called starchy endosperm of the grain, the source of white flour.

Normally very little of this particular iron transporter is present in the starchy endosperm, but in the high-iron wheat there is about 10 times more. As a consequence, more iron is transported into this tissue and retained there.

In the proposed crop trial a second piece of DNA has been added to the high iron wheat line. This tells the plant how to produce a specific molecule, an enzyme called NAS2 (NicotianAmine Synthase).

The first piece of DNA (VIT2) increases the iron content of white flour, but does not change the total amount of iron in the grain. By adding the NAS2 gene to our high-iron wheat line we aim to increase total iron in the grain, and the total zinc content.

The video below was produced for a previous successful trials of high iron wheat which used wheat genes to increase the iron content of the endosperm of the grain. The video explains how the process works in general terms, but does not include the specifics of the proposed trial.

Where do the genes come from?

DNA, or genes, from wheat, rice and maize are used in the high-iron wheat lines we are planning to trial in 2022 – 2024.

The gene VIT2 was isolated from the wheat genome, and placed behind a regulatory piece of DNA, also from wheat. This was then inserted back into the wheat genome.

The gene NAS2 was isolated from the rice genome, and placed behind a regulatory piece of DNA that drives increased production of the enzyme (and thus the compound) throughout the entire plant. The regulatory piece of DNA is from maize.

NAS2 from rice is well studied, and the regulatory piece of DNA from maize has been tested in wheat field trials in Australia. Wheat, rice and maize are closely related plant species, and because the equivalent genes in wheat have not been characterized or studied it is better to use the rice and maize sequences.

It should be noted that additional pieces of DNA were added to help the insertion of the DNA and to select for plants with the insertion. These extra pieces can be removed later as they are not essential for the aim of increasing iron in the starchy endosperm of the grain, but for now they have been left in as a research tool.

Why a field trial?

Several generations of this high-iron wheat have been grown in environmentally-controlled growth chambers and greenhouses to verify the inheritance of the high-iron trait and to see if there were any effects on plant growth.

So far, the high-iron wheat is indistinguishable from the parent line with respect to plant height and grain production, except that the white flour fraction has at least two times more iron and the bran fraction has more zinc. We would now like to test if this is the same when the wheat is grown in the field, where it will be exposed to the weather and regular UK pathogens.

We propose to study field trials of high-iron wheat during the spring and summer in each of three years (2022, 2023, 2024) to assess the consistency of the potential increase in iron, zinc and nicotianamine across years.

Is a field trial safe for the environment?

Yes. Wheat is widely grown in the UK, and the main risks to consider are the spread of pollen and spread of seed. Wheat pollen is relatively heavy, and cross-pollination is very rare 7. We will leave a zone of at least 20 meters between the high-iron wheat and other test plots of non-GM wheat to avoid the spread of pollen. From experience, this distance is more than sufficient.

The wheat is grown under a net to prevent birds from eating the seeds. When the grain is ripe, we will take care to harvest all the seed. In addition, the field trial site will be visited regularly by trained personnel to monitor the trial and to prevent any adverse environmental if these are suspected.  Emergency plans are in place should the need arise to terminate the trial at any point. In our previous field trials there were no effects on the environment or human health.

Who will benefit from high-iron wheat?

The primary reason to develop the high-iron wheat line is to help increase iron intake through plants in our diet, without resorting to chemical iron supplementation.

After further breeding for yield and disease resistance, we hope the high-iron wheat can be grown in  countries where wheat is a major staple crop and iron and zinc deficiencies are a major health issue, such as Bangladesh, northern India and Pakistan.

In addition, the iron biofortified wheat could potentially replace iron fortification in the UK. The fortification practice was enshrined in UK law in the 1960’s, but iron deficiency remains a problem.

According to the National Diet and Nutrition Study adolescent girls have on average an iron intake that is 25% below the recommended intake, and for women aged 19 – 64 it is 54% below the recommended amount. The intake of iron shows a declining trend over the last 8 years 8.

Who has funded the research?

The development of this particular wheat line was initially funded by the not-for profit organisation HarvestPlus (2013 – 2014), and subsequently it was publicly funded by the UK Biotechnology and Biological Sciences Research Council.

Where will the field trial be located?

If approved, the field trial will take place on a relatively small area of land (no larger than 50 m2), located at the experimental field station of the John Innes Centre in Bawburgh, Norwich.

How long will the trial go on for?

If approved, the field trial will take place from March to August, over three consecutive years, starting in March 2022.

Why do we apply for approval from Defra?

Approval is a legal requirement for field trials of genetically modified plants. Defra has created the Advisory Committee on Releases to the Environment (ACRE) to ensure each trial is safe and will not cause environmental damage. ACRE analyses the data provided and assess possible risks of the trial. It gives consent if it considers the trial is safe. The committee also gives advice and recommendations on how the trial should be carried out and monitored if the consent is granted. Finally, it checks that we comply with their requirements in every step of the process, before, during and after the trial.

What are the next steps in this application?

Defra considers the application, holds a public consultation and finally a Minister issues a decision. This takes at least 90 days.

At any time, further information or clarification may be requested by Defra. Defra invites representations on this application which can be made in writing to the GM Team (Department for Environment, Food and Rural Affairs, Defra Area 3B Nobel House, 17 Smith Square, London SW1P 3JR, stating the application reference number (22/R52/01)) or by emailing gm-regulation@defra.gsi.gov.uk (include the application reference number, 22/R52/01, in the e-mail title).

Where can I find out more information?

The application to Defra contains additional information (application reference number : 22/R52/01: https://www.gov.uk/government/publications/genetically-modified-organisms-john-innes-centre-21r5201.). You can also contact Professor Cristobal Uauy, a Group Leader at the John Innes Centre who leads the application (Cristobal.Uauy@jic.ac.uk).


  1. http://www.ffinetwork.org
  2. https://www.legislation.gov.uk/uksi/1998/141/contents/made
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  8. Lockyer et al., 2018. Nutrition Bulletin (https://onlinelibrary.wiley.com/doi/full/10.1111/nbu.12348)