The origin of potato pathogen leis nevertheless in the Andes
The potato pathogen Phytophthora infestans was responsible for the Irish Potato Famine. But where it exactly has its origin is a point of debate between scientists. Now American researchers hope to have cleared that up.
Phytophthora infestans, a fungus which likes potato plants, can have disastrous consequences. It caused the Irish Potato Famine between 1845 and 1852. The pathogen is still making its rounds, and farmers prefer to have potato plants that are Phytophthora infestans resistant. For this it is useful to know where Phytophthora infestans had its start. The potato plants there are co-evolved with the pathogen, and more likely to have natural resistance.
But the origin of Phytophthora infestans is a point of debate. Both Mexico and the Andes are possible contenders. The origin differs per publication. The American researchers hope to end this uncertainty for once and for all. Their plan of attack: To compare the genome sequence of a large number of Phytophthora species and variants.
Phytophthora infestans has more similarities with variants from the Andes
For their comparison the researchers compared multiple Phytophthora infestans variants together with Phytophthora variants from Mexico and the Andes that did not, like Phytophthora infestans did, travel the world. This showed that Phytophthora infestans has more similarities with variants from the Andes than variants from Mexico.
At the moment breeders use Mexican potato varieties to find genes that contribute to Phytophthora infestans resistance. Although this can be a good source, because for centuries the local population of the Andes and Mexico have been trading potato varieties. It also might be a good idea for breeders to also include potatoes from the Andes in the search for resistant genes.
Literature
Allison L. Coomber, Amanda C. Saville, Ignazio Carbone, Michael Martin, Vanessa C. Bieker, Jean Beagle Ristaino (2025) A pangenome analysis reveals the center of origin and evolutionary history of Phytophthora infestans and 1c clade species. PLOS ONE, 20 (1): e0314509 DOI: 10.1371/journal.pone.0314509
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