Reconstructing genome evolution in historic samples of the Irish potato famine pathogen

Michael D. Martin*, Enrico Cappellini, Jose A. Samaniego, Marie Lisandra Zepeda Mendoza, Paula F Campos, Andaine Seguin-Orlando, Nathan Wales, Ludovic Orlando, Simon Y. W. Ho, Fred S. Dietrich, Piotr A. Mieczkowski, Joseph Heitman, Eske Willerslev, Anders Krogh, Jean B. Ristaino, M. Thomas P. Gilbert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Responsible for the Irish potato famine of 1845-49, the oomycete pathogen Phytophthora infestans caused persistent, devastating outbreaks of potato late blight across Europe in the 19th century. Despite continued interest in the history and spread of the pathogen, the genome of the famine-era strain remains entirely unknown. Here we characterize temporal genomic changes in introduced P. infestans. We shotgun sequence five 19th-century European strains from archival herbarium samples-including the oldest known European specimen, collected in 1845 from the first reported source of introduction. We then compare their genomes to those of extant isolates. We report multiple distinct genotypes in historical Europe and a suite of infection-related genes different from modern strains. At virulencerelated loci, several now-ubiquitous genotypes were absent from the historical gene pool. At least one of these genotypes encodes a virulent phenotype in modern strains, which helps explain the 20th century's episodic replacements of European P. infestans lineages.

Original languageEnglish
Article number2172
JournalNature Communications
Publication statusPublished - 2013

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