According to a study published in the journal Plos One, the parasite that infected Ireland's potato crops and caused the great famine of 1845 had affected the US two years before that.
In the research, experts from North Carolina State University and the Norwegian University of Science and Technology also found historical samples of the pathogen in Colombia, suggesting that this parasite had a South American origin.
The most common theory regarding the potato shortage that led to the Great Irish Famine (1845-1849), which killed some 2 million people, is that the first infected tubers came from South America.
Jean Ristaino, author of the study, has a new theory: the plant pathogen might have also arrived in Europe in a shipment of infected potatoes from the United States.
Ristaino and her team have managed to trace the evolutionary line of different strains of this organism, which is called Phytophthora infestans, that is responsible for the late blight disease in potatoes or tomatoes.
To achieve this, researchers studied 12 key regions in the genomes of 183 samples worldwide. Some of these samples, which were isolated between 1992 and 2014, were recent, while others were older and belonged to the period between 1846 and 1970.
It also affected Colombia
The study allowed researcher to discover that a strain known as FAM-1 caused an outbreak of late blight in potatoes on US soil in 1843, two years before the disease was registered in the UK and Ireland. According to the authors of the study, this strain was also found in older samples that came from Colombia. "The FAM-1 strain spread and affected the US in the second half of the nineteenth century and early twentieth centuries," said Ristaino.
This strain survived in US territory for almost a century, until it was displaced by the US-1, another strain of the Phytophthora infestans. In turn, the US-1 was displaced by more aggressive strains from Mexico.
According to Ristaino, the effects of this parasite were not limited to the Irish crops of the nineteenth century, as producers worldwide spend billions of dollars every year to try to control this disease.
Source: EFE