It was a disaster that killed around a million people, devastating Ireland in the 19th century, but while the potato disease associated with the Irish Famine is well known, a battle has raged over where it originated.
Scientists have long been divided over whether it is a fungal-like pathogen Phtytophthora Infestans He grew up in the Andes or I grew up in Mexico.
Now a team of researchers says the question is settled after conducting what they describe as one of the largest whole-genome studies of the microbe and its close relatives — with results supporting a South American origin.
“That’s how science works. There’s a hypothesis, people wonder about it, it’s tested, and there’s existing data,” said Professor Jean Restaino, co-author of the research from North Carolina State University. “But over time, the evidence is really weighing in favor of the Andes, because the DNA doesn’t lie, the genetics show an origin in that region.” She added that the conclusion was recorded with historical documents.
“In 1845 when this pest hit Europe and the United States they were immediately trying to figure out where it came from,” Restano said. “There were reports that the disease occurred and was known among the indigenous Andean Indians who grew potatoes.”
Ristaino did not rule out further discussion, but said the amount of data available would be difficult to counter.
In the journal PLOS One, Ristaino and colleagues report how an analysis of the genomes of a microbe and its close relatives from South America and Mexico emerged from Mexico more recently than others.
The team found that contemporary populations of the potato blight microbe have a complex relationship, suggesting those found in Mexico, and the mixing of the Andes and Europe more recently.
But while contemporary populations of the microbe from the United States, Mexico and South America all emerged from historical populations from the 19th century, the researchers say the Mexican population is more recent.
“If Mexico is the center of origin, you would expect it to be rootstock, which is not the case,” Restano said.
Blight Potato continues to pose a threat, with Ristaino noting the presence of fungicide-resistant strains in Europe.
“Farmers have to consider different types of chemicals, and companies are trying to come up with different approaches,” she said. “Perhaps through breeding and genetically approved potatoes, there may be a long-term solution, but at the moment, it has become a worldwide problem in many parts of the world including in developing countries in Africa, South America and England.”
Understanding where potato blight originated was important, Restano said.
“When you know the center of origin of a pathogen, that’s where you’ll find resistance to it,” she said. “In the long term, the way to manage this disease is through host resistance, and… [this work shows] Focus on breeding efforts needs to occur in the Andes. “
Dr David Cook of the James Hutton Institute, an expert on Blight, who was not involved in the work, welcomed the research.
The origins of the pathogen remain up for debate, not least because populations in South America reproduce almost asexually, in other words by producing clones, while populations in Mexico reproduce mostly sexually which maintains diversity and helps prevent a kind of bad mutations from accumulating over time. the time.
“What we need as a smoking gun will be a survey in South America that reveals the sexual population,” he said.