Understanding Adaptation, Coevolution, Host Specialization, and Mating System in Castrating Anther-Smut Fungi by Combining Population and Comparative Genomics.

Anther-smut fungi provide a powerful system to study host-pathogen specialization and coevolution, with hundreds of Microbotryum species specialized on diverse Caryophyllaceae plants, castrating their hosts through manipulation of the hosts' reproductive organs to facilitate disease transmission. Microbotryum fungi have exceptional genomic characteristics, including dimorphic mating-type chromosomes, that make this genus an excellent model for studying the evolution of mating systems and their influence on population genetics structure and adaptive potential. Important insights into adaptation, coevolution, host specialization, and mating system evolution have been gained using anther-smut fungi, with new insights made possible by the recent advent of genomic approaches. We illustrate with Microbotryum case studies how using a combination of comparative genomics, population genomics, and transcriptomics approaches enables the integration of different evolutionary perspectives across different timescales. We also highlight current challenges and suggest future studies that will contribute to advancing our understanding of the mechanisms underlying adaptive processes in populations of fungal pathogens. Expected final online publication date for the Annual Review of Phytopathology Volume 57 is August 26, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.