Scientists have finally identified the strain of potato blight that caused the Irish famine and led to a million deaths and mass starvation.
In an article in IrishCentral.com dated 25 May 2013 by PATRICK COUNIHAN, IrishCentral Staff Writer:
New study sequences the genome and shows it originally came from Mexico
Scientists have finally identified the
strain of potato blight that caused the Irish famine and led to a
million deaths and mass starvation.
Phytophthora infestans, a fungus-like organism that devastated potato crops, led to the famine in Ireland according to an international team of molecular biologists.
They say the precise strain of the pathogen that caused the devastating famine from 1845 to 1852, had been unknown until now.
The newly identified strain of potato blight has been christened HERB-1 by the biologists according to the report on Yahoo news.
Study
co-author Hernán Burbano, a researcher at the Max Planck Institute for
Developmental Biology in Germany, said in a statement: “We have finally
discovered the identity of the exact strain that caused all this havoc.”
The report says that a Phytophthora strain called US-1 was thought to have triggered the potato famine.
But,
by sequencing the genomes of preserved samples of the plant pathogen,
the researchers discovered that a different strain, new to science, was
the real culprit.
Burbano added: “Both strains seem to have separated from each other only years before the first major outbreak in Europe.”
Researchers
studied 11 historic samples from potato leaves that were collected
about 150 years ago in Ireland, the United Kingdom, Europe and North
America.
The ancient samples, preserved
at the Botanical State Collection Munich and the Kew Gardens in London,
still had many intact pieces of DNA.
The
DNA quality was so good the researchers were able to sequence the
entire genome of Phytophthora infestans and its host, the potato, within
just a few weeks.
Johannes Krause, a
professor of paleogenetics at the University of Tübingen in Germany and a
study co-author, said: “The degree of DNA preservation in the herbarium
samples really surprised us.
The
decoded genomes were compared with modern Phytophthora strains from
Europe, Africa and the Americas and the results enabled the researchers
to trace the evolution of the pathogen, including where and when the
HERB-1 and US-1 strains likely diverged.
Their report says Phytophthora infestans originated in Mexico’s Toluca Valley.
When
Europeans and Americans first came to Mexico in the 16th century, the
pathogen experienced increased genetic diversity, and in the early
1800s, the HERB-1 Phytophthora strain emerged and was brought out of
Mexico, the researchers said.
They added
that by the summer of 1845, the HERB-1 strain had arrived at European
ports, and the potato disease spread throughout Ireland and the United
Kingdom, causing the Irish potato famine.
In
the 20th century, as new varieties of potatoes were introduced, the
HERB-1 strain was eventually replaced by the US-1 Phytophthora strain,
the researchers said.
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