18th February 2014

Genetically modified potatoes can resist blight

Genetically modified potatoes that resist blight – a fungus that caused the Great Irish Famine – have been developed by the John Innes Centre and the Sainsbury Laboratory in Britain.



GM (left) and non-GM (right) potato plants, a month after infection with blight. Credit: The Sainsbury Laboratory (TSL)

The Great Famine is considered the worst tragedy in the history of Ireland. This period of mass starvation and disease occurred from 1845-1852, leaving over a million dead and causing many more to leave the country. The proximate cause of the famine was Phytophthora infestans – a serious potato disease commonly known as blight.

Now, more than 150 years later, scientists have boosted the resistance of potatoes to blight, using genetic modification. The results of their trial were published yesterday in Philosophical Transactions of the Royal Society B.

During 2012, the third year of the trial, the potatoes experienced ideal conditions for late blight. The scientists did not inoculate any plants, but waited for disease strains circulating in the UK to blow in.

Non-GM potato plants of the Desiree variety were 100% infected by August, while all GM plants remained fully resistant throughout the experiment. There was also a notable difference in yield, with tubers from the 16 transgenic plants weighing 6-13 kg, while the non-GM tubers weighed only 1.6-5 kg per block.

The introduced gene, from a South American wild relative of potato, triggers the plant’s natural defence mechanisms by enabling it to recognise the pathogen. Cultivated potatoes possess around 750 resistance genes – but in most varieties, late blight is able to elude them.

“Breeding from wild relatives is laborious and slow and 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,” said Professor Jonathan Jones from The Sainsbury Laboratory (TSL).

“With new insights into both the pathogen and its potato host, we can use GM technology to tip the evolutionary balance in favour of potatoes and against late blight.”

Blight causes annual worldwide losses of about £3.5 billion ($5.8 billion), according to TLS. As well as the economic costs, frequent chemical sprays lead to soil compaction from tractor journeys and CO2 emissions from diesel fuel. In parts of northern Europe, farmers often spray a potato crop 10-15 times, or up to 25 times in a bad year. Scientists hope to replace chemical control with genetic control.

The researchers have licensed their technology to an American company, Simplot, which wants to grow them in the US.

"I think it is unfortunate that American farmers are going to benefit from the fruits of European taxpayers' funded work way before Europeans," Jones told the BBC. "This kind of product will likely be on the US market within a couple of years and if we are lucky within eight to 10 years in Europe."

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