New research has shown that a strain of genetically-modified potato appears to be immune to the devastating fungus responsible for the famine of 1845.
Late blight, caused by the organism Phytophthora infestans, remains the farmers' greatest enemy each year. Farmers spend millions of dollars keeping the infection at bay with pesticides.
In a bad year, losses and control measures combined can account for half the total cost of growing potatoes.
In the trials carried out outside Norwich, in England, the Desiree potato – a strain developed in the Netherlands in the 1960s – was altered by a gene taken from a wild variety of potato, Solanum venturii.
The aim was to produce a crop that could fight off blight without the aid of chemicals.
The Desiree, a waxy variety of potato used in all types of cooking from roasting to mashing, has been favored by growers because it is resistant to disease.
Over three years, between 2010 and 2012, a genetically modified version of Desiree was grown alongside non-GM varieties to test the GM plant's ability to withstand potato blight.
Lead scientist Professor Jonathan Jones of the Sainsbury Laboratory said, "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.
"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."
In the latest of a series of field trials, conducted in the UK in 2012, the fungus was unable to break down the defences of any of the GM potatoes.
However, no-one can say at this stage how long the GM strain will hold out against blight, which is notorious for its ability to overcome resistance.
Scientists are now conducting further research aimed at identifying multiple resistance genes that will thwart future blight attacks.
The new research, which focused on Desiree potatoes, addressed the problem of reinforcing blight resistance while maintaining crop characteristics pleasing to producers and consumers.
During three years of trials, the scientists grew potatoes containing a gene from a super-resistant wild strain from South America.
Normal cultivated potatoes naturally possess around 750 resistance genes, but in most varieties late blight is able to evade them.
RTE News reports that ‘In 2012 the researchers took advantage of a year with ideal conditions for late blight. Instead of inoculating the plants, the scientists waited for them to be infected naturally by spores blowing on the wind.’
By early August, 100% of the non-GM potatoes in the study were infected. In contrast, all the GM plants maintained full resistance against the pest until the end of the experiment.
The Irish potato famine first hit in 1845. It is estimated that one million people died and over one million emigrated, reducing the population by a quarter.
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