Blight-resistant GM potatoes field trial begins

Researchers say the GM potatoes will drastically cut the use of fungicides

A field trial of a genetically modified (GM) variety of potato resistant to "late blight" - a major threat to the crop - has begun in eastern England.

The global annual cost of crops lost to the disease is estimated to be £3.5bn.

The trial, carried out by scientists from The Sainsbury Laboratory (TSL), will last three years.

Anti-GM campaigners criticised the trials, saying it was possible to grow blight-resistant potatoes using conventional methods.

The project's research team said it was necessary to carry out the field trial in order to test the plants' resistance to naturally occuring pathogen Phytophthora infestans - the fungus that causes late blight in potatoes.

"What we don't know is if we have got a GM potato, which is resistant to laboratory strains of the late blight pathogen, (whether) that will be resistant to the whole spectrum of races that circulate out there in the field," said Jonathan Jones, TSL's senior scientist.

The experiment will be conducted on a 1,000-square-metre plot in Norfolk. Each year of the trial, approximately 200 sq m, containing about 400 plants, will be sown with GM potatoes.

Professor Jones said that the team started screening wild gene-banks for sources of resistance to late blight.

"We screened about 100 different species of Sollanum, the genus to which potatoes belong, and identified a few that were resistant," he told BBC News.

"We have isolated genes from two different wild potato species that confer blight resistance."

The genes, taken from inedible wild plants that grow in South America, were used to to produce a genetically modified Desiree variety.

The genes give the Desiree plants the ability to recognise strains of the blight pathogen that it would not otherwise recognise, Professor Jones explained.

"A new race showed up about four or five years ago, but is now about 70% of all (racees) you see in the field. It has overcome previously resistant varieties of potato.

"So you use the pathogen's attack as your defence. The resistance genes allow the plant to discern a pathogen attack as a cue to activate the host's defences."

About 130,000 hectares of land in the UK is used to grow potatoes, yielding in the region of 6m tonnes of potatoes each year.

However, in a typical growing season, farmers can spray fungicides on their crops up 15 times at a cost of about £500/hectare, Professor Jones said.

Therefore a late blight resistance GM potato would reduce a number of environmental impacts, including reducing the amount of chemicals being sprayed on farmland, as well as cutting emissions from using tractors to spray fungicides and from the production of the agrichemicals.

Biosecurity concerns

Dr Helen Wallace, director of campaign group GeneWatch, called the trial a "waste of public money".

"It is possible to breed blight-resistant potatoes using conventional methods, so there is no need to use GM technology," she told BBC News.

GM Freeze, another group opposed to genetically modified food crops, voiced a number of objections to the trial, which has been approved by the Department for Environment, Food and Rural Affairs (Defra).

"The application from the Sainsbury Laboratory states that potatoes are mainly self-pollinating and that dissemination of pollen 'is usually less than 10 metres' and the role of the wind is 'very limited'," it said in its objections.

"Pollination is also by insects, including bumble bees, pollinated hoverflies and pollen beetles. Long distant cross-pollination events have been found to occur.

"Distances for potato-to-potato cross pollination events of up to 1km have been recorded in which pollen beetles were believed to be the vectors."

They added: "Thus, the justification for very limited separation distances and safeguards against pollen escape are open to question."

Professor Jones said that the trial was well within the biosecurity parameters required in order for permission to be granted.

"The rules are that the field trial has to be at least 20 metres from adjacent conventional potato fields," he said.

"Very hypothetically, if a few pollen grains make it from our GM potatoes to some cultivated potatoes, given that we do not eat the fruit but the tubers, there is absolutely no way that the DNA we use can enter the human food chain."

"There are also no wild relatives of potato in Europe that it could cross (breed) with."

Food for thought

Helen Ferrier, the National Farmers Union's chief science and regulatory affairs adviser, welcomed the start of the field trial.

"We are encouraged that there is research into tackling this problem and it is progressing into field trials, as blight is a major issue for the potato sector," she told BBC News.

However, she added that there would not be any commercial cultivation of GM potatoes in the UK unless there was a market for it.

"At the moment, it is a bit of a leap of imagination for farmers to think that they will be growing this crop.

"But they are always looking for ways to produce more sustainably, so in the future if there is a market, then some farmers will go for it."

Professor Jones said that if there was no public controversy about using technology, then the first GM potatoes could be available to commercial growers within five years.

"However, the wild card is the public mood," he added.

"What will be required in order for this technology to move forward is for supermarkets to say that they are not scared to tell customers that food produced this way will reduce the environmental impact of agriculture and will be better value.

"But we are not at that stage yet."

As a member of the Royal Society panel that produced a report last year examining the role of science in delivering a sustainable global food system, Professor Jones said that GM technology offered a possible solution to delivering food security.

"We do face a 'perfect storm' of needing to produce at least 50% more food by 2030 with no more land, less water, climate change and rising costs of energy and fertilisers.

"This is not a trivial challenge at all, and this technology - I believe - is one of the essential (items) in the toolkit to meet that challenge."

Professor Jones and his team hope to publish initial results of the field trial, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), in a scientific journal by the end of the year.