Scientists Track the Origins of the Irish Potato Famine to Battle $6 Billion Global Problem

The potato blight that caused the Great Irish Famine of the 1840s left families starving as their source of food was left rotting in their fields. Now, though, researchers have tracked the origin of this blight, and have found that the deadly plant disease actually first originated in an alpine valley in central Mexico.

The potato is thought to have been first domesticated more than 7,000 years ago in parts of what are now Peru and Bolivia. It was first brought to Europe by Spanish explorers in the late 1500s. These days, though, each person on Earth eats, on average, more than 70 pounds of potatoes a year. These tubers possess a range of vitamins, minerals, phytochemicals, fiber and needed calories.

It's important to learn the origins of plant diseases. As our world becomes more open, people can carry diseases from one continent to another in just a matter of hours. Knowing a disease's origins can allow scientists to potentially discover resistance genes and can explain the repeated emergence of a disease.

This potato pathogen is called Phytophthora infestans, which probably co-evolved with potatoes over hundreds or maybe even a few thousand years. To this day, it's still the most costly potato pathogen in the world. In fact, about $6 billion a year is spent to combat it.

So how did the researchers find the origins of this pathogen? They used gene sequencing technology in order to find out that the Toluca Valley in Mexico was where Phytophthora infestans originated. It evolved with distant cousins of modern potatoes, which produced tubers but were more often thought of as a weed than a vegetable crop.

"This is immensely important," said Niklaus Grunwald, one of the researchers, in a news release. "This is just a textbook example of a center of origin for a pathogen, and it's a real treat. I can't think of another system so well understood. This should allow us to make significant headway in finding additional genes that provide resistance to P. infestans."

The findings may pave the way for creating new tools to deal with P. infestans and protect potato crops.

The findings are published in the journal Proceedings of the National Academy of Sciences.