Pathogen responsible for Irish Potato Famine originated in Peru, not Mexico, says study

The pathogen responsible for the Great Irish Potato Famine of the 19th century that killed millions of people in British-ruled Ireland and led to global Irish emigration, originated in Peru, according to a new study.

Phytophthora infestans, which causes potato blight and still remains a major threat to potato crops globally, likely originated in the Andes mountain range.

From there, it migrated north to Colombia and Mexico and then spread to the United States, Europe, and Asia, according to the study.

The team of researchers used advanced statistical methods to reconstruct the likely migration routes. They analysed genotypic data from 1,706 isolates collected worldwide.

Their findings contradict earlier research according to which Phytophthora infestans originated in Mexico. The researchers also did not find any indication that the pathogen returned to the Andes after the migration.

The research not only unravels the past migrations of P. infestans but also provides a framework for predicting its future movements, according to Silvia Restrepo, lead author of the study and president of the Boyce Thompson Institute in the United States.

“This is essential for global efforts to safeguard potato crops against this persistent threat,” she added.

The potato is the largest non-cereal food crop worldwide. It ranks as humanity’s fourth most important food crop after rice, wheat, and maize.

The potato originated in the Andes, in a region consisting of southern Peru and northern Bolivia. It spread from the Americas to the rest of the world as a result of the Columbian Exchange, the exchange of people, food crops, animals and diseases between the Old and New Worlds as a result of European colonisation of the Americas.

The potato was first brought to the Indian subcontinent by the Portuguese. Edward Terry, an Englishman who was the chaplain of Sir Thomas Roe (the English diplomat who was James I of England’s envoy to Mughal Emperor Jehangir’s court in Agra), made the first mention of its use in India in his travel accounts.