Field trial of late blight resistant potatoes Q&A

Defining the problem
The solution
Why in Norfolk?
The future


Defining the problem

What is late blight and why is it important?

A: Late blight caused by the fungus-like organism Phytophthora infestans ravaged potato crops during the 19th century and caused the Irish potato famine. This disease is still a major threat, causing enormous economic damage in potato and tomato. Globally, potato late blight causes about £3.5 billion annual losses.
In the UK, potatoes are currently planted on about 130,000 ha, yielding ~ 6m tonnes of potatoes with a farm gate value of around £600m. It costs ~£350/hectare to control late blight and in a high pressure blight season the cost of control for the UK can be up to £72M.

In a typical season, UK potato farmers spray fungicides 10-15 times to reduce losses to blight. However, this does not completely prevent crop losses and has an associated negative impact on the environment due to the chemicals released to the environment, the CO2 emissions from tractors used to apply the sprays and compaction caused by tractor journeys. Growing blight resistant crops will greatly reduce crop losses to the disease and reduce the number of fungicide sprays required, thereby having both economic and environmental benefits.

Aren’t blight resistant varieties of potato already available?

Yes, but the more blight-resistant varieties are not yet widely accepted in the market. We have worked and continue to work on Sarpo Mira, and are supportive of the efforts of the Sarvari Trust in promoting their potato varieties – see our published work:  Some of our results should be helpful for breeders trying improve potato, and we believe both breeding and GM can significantly contribute to potato improvement. There is an urgent need for blight-resistant potatoes that address market needs and significantly reduce chemical input. We can never have ‘too many’ resistance genes available for use.

Why do these potatoes need to involve GM technology rather than being conventionally bred?

A: Potato breeding is extremely slow and inefficient. By the time a gene is successfully introduced into a cultivated variety, the late blight pathogen may already have evolved the ability to overcome it. It is better to take a good variety like Maris Piper (~20% of the market) and enhance its blight resistance than to try to breed a blight resistant Maris Piper. Breeding is not an exact science and changes many genes that affect important agronomic traits such as yield, quality and maturity time. By using GM, we can be sure that only the desired resistance gene is introduced into the resulting variety, without changing other characteristics.

Who is providing the funding for the trial? Is there any commercial funding?

A: The trial is funded by the UK’s Biotechnology & Biological Sciences Research Council (BBSRC). BBSRC funds and supports the use of GM as a laboratory tool and research to investigate the feasibility of producing GM crops with specific beneficial traits.


The solution

What genes have been used to create the GM potatoes?

A: Two genes that give potatoes resistance against the pathogen have been isolated from wild South American potato species. The wild South American species are not edible potatoes and are not suitable for cultivation in Europe or elsewhere. In addition to well characterised laboratory races, we also know that one of the genes is effective against the race of Phytophthora infestans that was prevalent in the recent serious UK epidemic years of 2007 and 2008 (known colloquially as 'superblight' or Blue 13). The potatoes also contain a gene which confers resistance against the antibiotic kanamycin. Kanamycin is used during the genetic modification process as a means to select plant cells that also contain the inserted resistance genes. This antibiotic is not used for medical treatment of either humans or animals. One of the Rpi genes (Resistance to Phytophthora infestans genes) was isolated from a wild species using two successive BBSRC grants. The other was isolated partially with BBSRC and partially with EU funding.

Are the products of the genes toxic?

A: No, not even to the late blight pathogen. The resistance genes give the plants the ability to recognise strains of the late blight pathogen that they are normally unable to recognise. In effect, the presence of these genes “immunises” the plant against the disease. Following recognition, the plant’s own in-built defence mechanisms then prevent the pathogen from growing further and causing disease on the plants.
The product of the kanamycin resistance gene has also been shown to be non-toxic to humans and animals. The tubers produced by the potato plants in this trial were destroyed following harvest and did not enter the human or animal food chain.

What would you say in defence to those who think GM trials should not be carried out?

A: Our approach has a high likelihood of helping to minimise the impact of agriculture on the environment by reducing applications of fungicides for late blight control. BBSRC supports, and has full confidence in, the UK regulatory framework for research on GM crops. This is particularly the case when scientists are working to provide objective evidence about some of the potential benefits that are seen by some as contentious.

What is the point in carrying out this research when there has been no take-up of GM products in the UK so far?

A: BBSRC funds basic plant science that underpins a range of farming systems, including organic and low-intensity farming. While GM is a powerful tool and offers significant potential it may not be the most appropriate way to tackle some problems, while in other cases it may be the only feasible option for introducing particular traits. We believe that the scientific challenges in feeding a growing global population places a responsibility on us, as publicly funded researchers, to investigate thoroughly all potential ways that bioscience and biotechnology might be used to increase food production sustainably – including, for example, GM in breeding and natural bio-agents in pest and disease control.

What are the potential benefits of the potatoes? Is it in the end just more profit for farmers? Or is this just about making food even cheaper for supermarkets?

A: The goal of the trial was to assess if this approach to enhance crop disease resistance could be successful. If the approach can be deployed widely, there will be a reduced impact of potato cultivation on the environment because of reduced need to apply agrichemicals. This benefits everyone; consumers as well as farmers.

Why do the scientists say “the gene worked” when it looks like it only worked in 2012?

There was little blight in 2010 and the GM plants were planted late due to a delay in authorisation. The delay caused the plants physiological stress due to reduced light. The non-GM controls were grown in the field from tubers. The GM plants were still clearly more resistant to late blight than non-GM controls or plants with another gene, Rpi-mcq1.

In 2011, the second year of the trial, there was so little blight during the growing season it was not possible to see if the addition of the Rpi-vnt1 gene made GM plants more resistant to blight than non-GM plants. 

2012 was a very wet year, creating ideal conditions for the late blight pathogen which destroyed control plants by the end of August. Rpi-vnt1 plants were resistant and survived until the end of the season. The blight came into the crop so early that the non-GM control plants were affected in their ability to produce a good yield of tubers, hence the marked difference in tuber yield between the GM and non-GM plants.

Why were Sarpo potatoes not used as the control?

The GM and non-GM Desiree plants were different only by the addition of a gene, Rpi-vnt1, introduced to enable the GM plants to recognise the late blight pathogen and mount a defence response. The study is designed in this way so the effectiveness of the gene in a popular commercial potato variety can be assessed. This assessment would not have benefited from comparison to another blight-resistant variety.




Why in Norfolk?

Why was the trial in Norwich?

A: The trial was conducted by leading UK scientists working on plant disease and plant disease resistance at The Sainsbury Laboratory on Norwich Research Park. It was conducted in closely supervised conditions, with top-quality support, where scientists could easily monitor the outcome.

What is the Sainsbury Laboratory at the John Innes Centre?

A: The Sainsbury Laboratory ( was set up in 1988 to better understand biological interactions between plants and microbes. It was established as a joint venture of John Innes Centre, UEA, BBSRC and the Gatsby Charitable Foundation (see, one of David Sainsbury's private charities, and receives core funding from Gatsby. In addition to Gatsby funding, the lab wins grant funding by submitting competitive grant proposals to BBSRC, EU and other public bodies. The Lab has no interaction with J Sainsbury Plc.

Were local residents and farmers informed?

A: Notification of intent to carry out the trial appears in the Daily Telegraph issue of 11 February 2010. We also put details on The Sainsbury Laboratory website. Local councils, key public bodies and local media were been informed. The National Farmers Union was informed.

There are farms and residential areas nearby – do people need to be worried about GM material escaping and crossing with their crops and plants?

A:  The pollen from potatoes does not travel significant distances, typically less than 10 metres. Potatoes cannot cross with any other naturally occurring species. In the extremely unlikely event that the GM potatoes did cross with cultivated potatoes, any seed produced would not be saved as potatoes are grown from tubers. The pollen itself does not pose a threat to humans or other animals.

What size was the plot?

A: The total area dedicated to the field trial was approximately 1000 square metres. Each year of the trial, approximately 200 square metres was sown with the GM potatoes. Two GM potato lines were sown; no more than 200 plants of each line were sown each year of the trial.


Why was’t the trial carried out in a glasshouse?

A: We have done glasshouse trials and we now need to know if the resistance works in the field.
Resistance will be tested against the naturally occurring populations of Phytophthora infestans. The only way to see if the potatoes resist the blight race diversity circulating in nature is to conduct a trial outside


The future

Who will own the rights to any commercial discoveries / crop products?

A: The rights are owned by The Sainsbury Laboratory and handled by Plant Bioscience Ltd, the Sainsbury Laboratory’s IP management company. The rights for one of the genes are shared with Wageningen University, The Netherlands.

Do the inventors stand to make money?

A: If the technology proves useful, is licensed and is commercially deployed, then the TSL Rewards to Inventors scheme means that the inventors will share in some of the royalties with the laboratory.

What will the next stage be – when and where could they be grown commercially?

A: In a new BBSRC-funded industrial partnership award with American potato company Simplot and the James Hutton Institute, the TSL researchers will continue to identify and experiment with multiple resistance genes. By combining understanding of resistance genes with knowledge of the pathogen, they hope to develop Desiree and Maris Piper varieties that can completely thwart attacks from late blight.
Farmers are keen to be able to deploy blight resistant varieties. Once consumers see that this technology confers great benefits to the environment, we hope that supermarkets will stock some form of GM blight resistant potatoes and offer this choice to consumers.

Would future GM blight resistant potatoes be available to the domestic grower or simply be held by one ‘supergrower’?

A: The potatoes being grown in this trial will not be available commercially. The purpose of this trial was to test the efficacy of the blight resistance genes. Since this trial was successful, we hope that companies will want in the future to licence the genes and deploy them in commercial crops. For this to happen, a potato breeding company will produce varieties that carry the blight resistance gene(s), and farmers who wish to plant these varieties will buy seed potatoes from the breeding company and then plant them. So far, one American company (Simplot) but no European companies have taken out a license to one of the resistance genes in this trial via Plant Biosciences Ltd.

The Sainsbury Laboratory,
Norwich Research Park,
Colney, Norwich
NR4 7UH, UK.
Tel: +44 (0)1603 450400
Media enquiries: +44(0) 1603 450962; +44(0) 7768 164185

February 2014