XVI International Botanical Congess

How might the population structure or history affect the coevolution of corn smut and corn? We are addressing this question by: examining the population structure of U. maydis over the broad geographic range of its host, Z. mays and using the b mating type locus of U. maydis to reconstruct the history of these populations. Our evidence to date indicates that more geographically distant populations of this pathogen may be genetically isolated from the widespread North American populations. Because the genealogy alleles at the b locus exhibits deep divergences as well as more recently diverged alleles, we will be able to use this genealogy to trace the history of these populations. The evidence to date indicates that new b mating types may be evolving at a higher rate in more isolated populations, perhaps due to selection for mating type diversity.