Tillage focus: GM potato study – see the results here

The environmental impact of potato production can be reduced by 95% by using a genetically modified (GM) blight-resistant potato in combination with a novel integrated pest management strategy.

AgriLand met Dr. Ewen Mullins, the head research officer involved in the four-year GM potato environmental trial carried out at Teagasc Oak Park, to hear all about the results of the AMIGA project – which have now been published – and to understand what the trial was all about.

“Our goal in the AMIGA project wasn’t to advocate the merits of one production system over another. We wanted to look at the agronomic and environmental impact of growing this specific GM potato relative to current systems,” Ewen explained.

Dr. Ewen Mullins in Teagasc Oakpark yesterday

A few facts about the trial:
  • It was set up to examine the impact of the GM potato variety on the environment;
  • To examine if this variety stood up to late blight in Ireland;
  • The trial was part of the ‘AMIGA’ project in collaboration with Wageningen University in the Netherlands;
  • The GM potato in the trial was engineered in Wageningen University through cisgenesis.

How was the GM potato engineered?

According to Ewen, the University of Wageningen had a separate publicly-funded programme (DurPh) which was investigating the role of cisgenics as a tool to breed novel varieties.

“The traditional understanding of GM is where you transfer, for example, a gene from a fish into a carrot . This is transgenics and in this case it will never happen naturally,” Ewen explained.

“With cisgenics, what you’re doing is accelerating the breeding process by transferring a gene from a wild potato into a conventional variety, in effect potato to potato. At Wageningen, they took a gene from a wild potato – Solanum venturii – and transferred it into Désirée – just the potato DNA with no bacteria or viral DNA included.

“That can happen naturally, but it takes a long time to breed a new potato – on average about 13 years,” he said.

L-R: Désirée (conventional) and Désirée (engineered)

So why carry out cisgenics?

Cisgenics speeds up the breeding process.

“It is considered a GM potato, but really, with cisgenics all you’re doing is accelerating the breeding process, bringing in a single wild gene (here it was called VNT1).

If you cross a wild potato with a conventional potato you will bring in the gene that you want, but you will also bring in thousands of other genes that you don’t want.

“So what they did in Wageningen was focus in on the single gene and using cisgenics they were able to transfer one gene into the potato. Cisgenics is considered a novel breeding technique because you’re effectively enhancing an existing variety.”

L-R: Désirée (conventional) and Désirée (engineered)

Examining the engineered variety in Ireland?

The trial allowed the cisgenic variety to be examined in Ireland for its resistance to blight strains in this country and to also investigate its environmental impact.

“They had indications previously in the Netherlands that the gene could actually confer late blight resistance, but strains in the Netherlands are very different to strains in Ireland.

Ewen described late blight pressure in the Netherlands as “phenomenal”.

“We would typically get blight in mid-July, whereas they would get it in mid-June, so their blight season is much longer; but they have more intensive potato cropping in a smaller area relative to what we would have, so the blight pressures are much higher.

It stood up very well in the Netherlands, which gave more confidence that the source of resistance would stand up very well in Ireland.

“We also had Sarpo mira in the trial, which is a variety favoured by organic growers and that has up to five of these wild genes.”

L-R: Désirée (conventional) and Désirée (engineered)

Environmental yardstick for pesticides

In the Netherlands, the team at Wageningen used an internationally-recognised environmental yardstick for pesticides which is used to monitor the impact of pesticide use on the environment.

With a conventional potato system the metric scores around 700 points. That’s because conventional potatoes have negligible genetic resistance and are reliant on 10 plus sprays of fungicide. The cisgenic variety scored 10 points because of its significantly lesser requirement for fungicides.

“The Sarpo mira variety which was also included in the study has really good resistance as well – it gets a bit of late blight at the end of the season – and scored 40 points.

“Fundamentally, the study reiterates the need for durable genetic resistance. It’s the only way if we’re going to cut back on fungicides.”

Désirée is a very popular variety in mainland Europe and was chosen by Wageningen University for the study. It has no resistance to late blight and is amenable to the lab techniques involved in cisgenics. Sarpo mira has good resistance to late blight, but it does not meet all of the requirements for consumers.

“We were looking at how quickly late blight could adapt or evolve.

“We found that late blight wasn’t adapting or evolving to these sources of resistance during the course of the field study, which is very encouraging,” Ewen explained.

The AMIGA trial in Teagasc:
  • One fixed site;
  • One of two sited in Europe (Ireland and the Netherlands);
  • Site was in grass for 10-15 years before the trial;
  • Fenced in – as per the EPA (Environmental Protection Agency) licence;
  • Plots rotated onto new grass within that contained site each year;
  • No potato crops were sown into ground where a potato had been grown already;
  • Three treatments – a control; standard production and a novel Integrated Pest Management system, called IPM2.0.
Drone footage of the GM potato trial at Teagasc Oak Park

Examining the environmental impact

“We looked at the environmental impact of each production system using the yardstick measurement, but we also looked at nematodes, which are microscopic worms which are in effect a barometer of a soil’s health.

“Basically what we found is that there was no difference in nematode community abundance or diversity between the Désirée and the engineered Désirée. What we did see was a significant difference between varieties, so between Désirée and Sapro mira there was a big difference because they are completely different plants in regards to biomass and structures,” Ewen explained.

We also saw a huge difference year-on-year, as the climate has a huge impact on the nematode abundance and diversity.

Results

The photographs throughout the article also show the control plots of Désirée and engineered Désirée.

The conventional version of Désirée suffered from severe late blight, while the engineered variety showed high levels of resistance to late blight in all three years of the study in both Oak Park and the Netherlands.

“What we saw is that you can reduce the need for fungicide inputs by 80-90% by using a single source of genetic resistance, which in this case was a gene taken from a wild potato species.

Ultimately, how you get the resistance into the plant is the nub of it. Do you use conventional breeding, which takes many, many years or do you use an accelerated form of breeding, such as cisgenesis?

Why use the cisgenic variety?

“We have novel strains of blight migrating into Ireland and these strains are more aggressive and result in higher levels of disease.

As a result farmers are more and more reliant on fungicides to control blight but that is not sustainable, from either an economic or environmental perspective.

“On top of that, the EU is mandating that certain chemistries are removed from the registered list and therefore are not available to farmers.

“Spraying is a necessity at present but, if chemistries are removed, there has to be a viable alternative. Based on our research, cisgenic bred varieties may provide one solution.”

Informing the public

Over the past three years the project team has completed 96 knowledge transfer events and discussed and presented on the project to thousands of people: stakeholders; farmers; and consumers.

“The experience when you walk in first is that people are not overly happy; they are apprehensive and want to know why the research is necessary. However, when you explain the challenges that farmers face, and the issues that we have, they want to know what the solutions are.

We’re not advocates of GM or any other production system. We’re advocates of knowledge, so from that starting point we explain what the possible solutions could be.

“You can try and breed a new variety but, while it might have blight resistance, it won’t have all the other traits you want. Are you willing to accept that?

“Or you can consider something like cisgenics – for example, take an existing variety like a Kind Edward, a beautiful potato with no capacity to resist blight, and make it a King Edward plus. It’s for the consumers to decide at the end of the day. It’s not for us to decide.”

Ewen explained that it is important to have a discussion about new breeding techniques. The world population is getting bigger; food production needs to be sustainable. The EU is also cutting back on a lot of fungicides that can be used in crop production.

No farmer likes to spray, but they have to spray. If Europe is saying you can’t use certain chemistry, what are the alternatives? We have to breed new varieties with durable genetic resistance.

“That’s fine; we know we have to do that, but we need to be able to use all of the techniques that are available to us – assuming there is no negative environmental impact.”

Farmer reaction to the study

Ewen thinks that, during the course of the AMIGA study, farmers in general showed strong positivity to the research.

He stated: “More so I think because Teagasc was doing it. They know we are impartial because there was no industry linkage with this project.

Prior to the AMIGA project we surveyed potato farmers and just over 60% of farmers said they would seriously consider growing it – but obviously this will only occur if consumers will buy it. That’s really where the issues are.

A Euro-barometer carried out in Ireland a few years ago showed that, while only 37% of consumers would consider consuming a transgenic crop, 61% would eat a cisgenic crop.

“That showed that the consumer can delineate between the different forms of breeding, cisgenics versus transgenics” Ewen added.

“It’s a societal decision, but now that the AMIGA study has concluded at least consumers and all stakeholders can now make their decisions based on Irish specific datasets and knowledge that is the most relevant to our potato production systems.”