Research reveals movement and evolution of potato famine pathogen

The pathogen responsible for the Irish potato famine that killed more than a million people may have originated in South America. That's the conclusion of a team of scientists from North Carolina State University who recently analyzed the movement and evolution of the potato pathogen.

Scientists analyzed the genome of 183 samples of the pathogen Phytophthora infestans, both historic and modern, collected from 12 key regions. Their analysis revealed the origins of the P. infestans lineage known a FAM-1, the strain responsible for the catastrophic outbreaks of blight among potato crops in the United States, Great Britain and, most infamously, Ireland.

Genetic analysis suggests the strain jumped the Atlantic via infected potatoes from either the United States or South America.

"FAM-1 was widespread and dominant in the United States in the mid-to-late 19th century and the early 20th century," Jean Ristaino, a professor of plant pathology at N.C. State, said in a news release. "It also was found in Costa Rica and Columbia in the early 20th century."

"FAM-1 survived for about 100 years in the United States but was then displaced by a different strain of the pathogen called US-1," Ristaino explained. "US-1 is not a direct descendant of FAM-1, but rather a sister lineage."

The new research was published in the journal PLOS ONE.