Fig. 5: Worldwide migration patterns hypothesis over time and throughout the world.

Different colors represent the approximate time periods when the proposed events occurred. (1) Firstly, we have the Fertile Crescent being the origin of the pathogen. (2) Then, it splits, migrating to East Asia. (3) Migration of powdery mildew across all Eurasia. (4) During the colonization of America, Eurasian wheat powdery mildew was introduced to the Americas, which recombined with a distantly related powdery mildew, followed by isolation on this continent. (5–6) Later, the USA started exporting wheat to Japan and Australia, helping the pathogen migrate to both places. In Japan, because of the breeding of the American wheat lines with Japanese landraces, powdery mildew recombined between the East Asian and American populations and quickly got fixed because of adaptation to these new lines. (7) Finally, recent various levels of recombination between East Asian and European ancestry have been observed in the Chinese mildew population. The stars represent recombination events of populations that were fixed.