HUFFINGTON POST: …Now, using DNA from dried lumper potato leaves in herbariums, an international team has sequenced the genome of the organism that ravaged the Irish potato crop and found it was a single strain of the funguslike pathogen Phytophthora infestans — not the common strain of blight that had long been the prime suspect. It is the first time that scientists have decoded the genome of an ancient plant pathogen and its plant host from dried leaves—and the team found it was a strain that has vanished. “An extinct strain caused the pandemic in Ireland and Europe,” says Johannes Krause, a paleogeneticist at the University of Tübingen in Germany who is co-author of the paper published today in the open-access journal eLife. “We found it in all these leaves from Ireland, from England, from France, from Germany. One strain. Then, it just disappeared.”
The international team of molecular biologists traced the historical spread of the P. infestans, a funguslike oomycete, which arose in the Americas. The potato was first domesticated in modern-day Peru between 7000 and 10,000 years ago. The crop was introduced to Europe by Spanish explorers in the 16th century, shortly after their conquest of the Inca Empire. It soon became an important food staple that played a major role in the 19th century population boom in Europe. However, Europeans propagated the potato by planting a piece of potato—essentially growing clones of only a few varieties. As a result, when the blight reached Ireland on ships traveling between America and Britain, P. infestans rapidly spread through Ireland, resulting in the devastating famine. Even today, the Irish population of 4.5 million is less than three-quarters of what it was at the start of the famine… (more)
