Ustilago maydispopulations tracked maize through domestication and cultivation in the Americas

Abstract

The domestication of crops and the development of agricultural societies not only brought about major changes in human interactions with the environment but also in plants' interactions with the diseases that challenge them. We evaluated the impact of the domestication of maize from teosinte and the widespread cultivation of maize on the historical demography ofUstilago maydis, a fungal pathogen of maize. To determine the evolutionary response of the pathogen's populations, we obtained multilocus genotypes for 1088U. maydisdiploid individuals from two teosinte subspecies in Mexico and from maize in Mexico and throughout the Americas. Results identified five majorU. maydispopulations: two in Mexico; two in South America; and one in the United States. The two populations in Mexico diverged from the other populations at times comparable to those for the domestication of maize at 6000–10 000 years before present. Maize domestication and agriculture enforced sweeping changes inU. maydispopulations such that the standing variation in extant pathogen populations reflects evolution only since the time of the crop's domestication.