Pathogen that caused the Irish potato famine even more virulent now

Seed Daily via SPX: The plant pathogen that caused the Irish potato famine in the 1840s lives on today with a different genetic blueprint and an even larger arsenal of weaponry to harm and kill plants.

In a study published in the journal Nature Communications, North Carolina State University plant pathologist Jean Ristaino and colleagues Mike Martin and Tom Gilbert from the University of Copenhagen compared the genomes, or sets of all genes, of five 19th century strains of the Phytophthora infestans pathogen with modern strains of the pathogen, which still wreaks havoc on potatoes and tomatoes.

The researchers found that the genes in historical plant samples collected in Belgium in 1845 as well as other samples collected from varied European locales in the late 1870s and 1880s were quite different from modern-day P. infestans genes, including some genes in modern plants that make the pathogen more virulent than the historical strains.

...Some of the differences between the European historical samples from the 1840s and the 1870s and 1880s suggest that the pathogen was brought to Europe more than once, debunking the theory that the pathogen was introduced once and then expanded its range. Ristaino believes it was introduced to Europe multiple times, probably from South American ships.

P. infestans caused massive and debilitating late-blight disease outbreaks in Europe, leaving starvation and migration in its wake after ravaging Ireland in the mid-to-late 1840s. Ristaino's previous work pointed the finger at the 1a strain of P. infestans as the Irish potato-famine pathogen and traced its probable origin to South America...

The Great Famine National Monument. Detail from the bronze sculpture by John Behan depicting a "coffin ship" carrying emigrants following the 1840s famines. Shot by Bruce Hall, Wikimedia Commons via Geograph UK, under the Creative Commons Attribution-Share Alike 2.0 Generic license