Scientists Determine Blight Behind 19th Century Irish Potato Famine is Extinct

Posted on May 25, 2013

Scientists have identified the unique strain of potato blight that was behind the Irish potato famine of the mid-19th century. The strain appears to no longer exist. It is estimated that about 1 million people died during the famine, about 20% to 25% of Ireland's population. The famine was so bad that the Irish population has still not recovered to pre-famine levels.

The scientists have named the blight HERB-1. It is the first time scientists have decoded the genome of a plant pathogen and its plant host from dried herbarium samples.

Hernan Burbano from the Max Planck Institute for Developmental Biology, said in a statement, "We have finally discovered the identity of the exact strain that caused all this havoc."

The researchers examined the historical spread of the fungus-like oomycete Phytophthora infestans, known as the Irish potato famine pathogen. A strain called US-1 was thought to have been the cause of the fatal outbreak, but the study concludes that a strain new to science was responsible. The researchers compared the historic samples with modern strains as well as two closely related Phytophthora species. The scientists were able to estimate that the HERB-1 strain of Phytophthora infestans likely emerged in the early 1800s and continued its global conquest throughout the 19th century. In the twentieth century, after new potato varieties were introduced, HERB-1 was replaced by the US-1 strain.

The research paper was published in eLife.

PLANTS