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 (25 m2) of genetically modified (GM) wheat in the spring and summer of 2019.

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 removed together with the germ and bran.

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, confectionery etc.

Using modern methods of plant breeding, 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. Thus, in principle there would no longer be a need to add iron as an extra ingredient to wheat flour. Moreover, it was shown that the iron in this white flour in bioavailable (3, 5), suggesting that food products made from the biofortified flour could contribute to improved iron nutrition.

Increasing the nutrient content through plant breeding is called biofortification, which is more sustainable than adding vitamins and minerals separately to food products. Biofortified crops are currently being implemented in several developing countries to combat nutrient deficiencies, so called ‘hidden hunger’, focusing on vitamin A, zinc, iron and selenium. It would be great to add high-iron wheat to the range of biofortified crops, but so far it has appeared impossible to increase iron in wheat grain using conventional breeding.

How has the wheat been Genetically Modified?

The genetic material of wheat has been changed slightly by cutting and pasting. A piece of DNA encoding an iron transporter protein (which is called VIT2 for Vacuolar Iron Transporter 2) 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.

Because the DNA was first taken out of wheat and then put back into the genome, it is classified as genetic modification according to UK and EU laws. Some people call it ‘cisgenics’ rather than ‘transgenics’, because the genetic material is from the same species (cis) rather than from a different (trans) species.

However, 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 the 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 2 times more iron. 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 (2019, 2020, 2021) to assess the consistency of the potential increase in iron 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 (6). 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 in a cage 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 effects or adverse effects to human health. Emergency plans are in place should the need arise to terminate the trial at any point.

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 developing countries where wheat is a major staple crop and iron deficiency anaemia is a major health issue, such as Bangladesh, north 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 (7).

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 25 m2), located at the Norwich Research Park, Norwich.

How long will the trial go on for?

If approved, the field trial will take place from April to September, over three consecutive years, starting in April 2019.

Why do we apply for approval from Defra?

Approval is a legal requirement. 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 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 the minister issues a decision. All 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 (19/R52/02)) or by emailing gm-regulation@defra.gsi.gov.uk (include the application reference number, 19/R52/02, in the e-mail title).

Where can I find out more information?

The application to Defra contains additional information (application reference number 19/R52/02). 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
  3. Connorton et al., 2017. Plant Physiology (http://www.plantphysiol.org/content/174/4/2434)
  4. Balk et al., 2019. Nutrition Bulletin (https://onlinelibrary.wiley.com/journal/14673010)
  5. Eagling et al., 2014. Journal of Agricultural and Food Chemistry (https://pubs.acs.org/doi/10.1021/jf5026295)
  6. Hucl P, 1996. Canadian Journal of Plant Sciences (http://www.nrcresearchpress.com/doi/10.4141/cjps96-075#.XD7fWlygKUl)
  7. Lockyer et al., 2018. Nutrition Bulletin (https://onlinelibrary.wiley.com/doi/full/10.1111/nbu.12348)