UK scientists have identified a new genetic weapon in the "evolutionary arms race" to combat blight in potato crops.
Late blight, the cause of the Irish potato famine in the 1840s, continues to infect potato fields today and can cause devastating yield losses.
While resistance genes in plants provide a defense against disease, single resistance genes often act against a limited range of pathogens and can be overcome by new variants, said researchers. But scientists at the Sainsbury Laboratory, based on Norwich Research Park, have found "an excellent source of new resistance genes against late blight" in a wild plant related to the potato.
A team led by Jonathan Jones explored the genetic defenses of Solanum americanum, the ancestor of the widespread UK wild plant Solanum nigrum, also known as black nightshade. In a study published in the journal Nature Plants, they highlight a resistance gene named Rpi-amr1 and its many variants, most of which will recognize both of the two related "virulence proteins" carried by late blight strains. The researchers said this is significant because disease pathogens overcome resistance by losing or substantially modifying their virulence proteins through evolution, but the chances of modifying several virulence proteins at the same time is lower.
The team says the Rpi-amr1 gene confers resistance against all of the 19 blight strains tested, and is being combined with two other resistance genes in the commercial Maris Piper potato variety to produce new lines which are immune to a wide range of blight races.
“I'm delighted to see this important work out in print," says Jones. "It took a long time and there were many false leads and confusing data to make sense of, but this Rpi-amr1 gene now looks like one of the best resistance genes in our armoury against late blight. By combining Rpi-amr1 with two other resistance genes, I think it can make a durably blight-resistant potato."
Jones worked closely with Sophien Kamoun, also at The Sainsbury Laboratory, Vivianne Vleeshouwers from Wageningen University in the Netherlands, and other scientists from the John Innes Centre in the UK, the Technical University of Munich, and the Universities of East Anglia, Leeds and Hull.