The cause of potato late blight and the Great Irish Famine of the 1840s has been tracked to a pretty, alpine valley in central Mexico, which is ringed by mountains and now known to be the ancestral home of one of the most costly and deadly plant diseases in human history.
Research published today in the Proceedings of the National Academy of Sciences, by researchers from Oregon State University, the USDA Agricultural Research Service and five other institutions, concludes that Phytophthora infestans originated in this valley and co-evolved with potatoes over hundreds or maybe a few thousand years, and later spread repeatedly to much of the world.
Knowing the origin of the pathogen does more than just fill in a few facts in agricultural history, the scientists say. It provides new avenues to discover resistance genes, and helps explain the mechanisms of repeated emergence of this disease, which to this day is still the most costly potato pathogen in the world.
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