Fungus-growing ants and their microbial partners form a complex symbiosis, involving at least four integrated, coevolved, and anciently associated lineages that span three taxonomic kingdoms. At the center of the symbiosis is the obligate mutualism between the ant farmers and the fungi they cultivate for food. The ant-fungus mutualism is parasitized by microfungi in the genus Escovopsis, and to defend against infection, the ants have a mutualistic association with antibiotic-producing filamentous bacteria in the genus Pseudonocardia. The antibiotics produced by Pseudonocardia suppress the growth of the specialized parasite Escovopsis, and these compounds differ depending on the strain of bacteria. The genomes for three strains of Pseudonocardia that span the diversity of the mutualism will be sequenced, as well as the genome of P. saturnea, a closely related non-symbiotic species. In addition, optical maps for the genomes of 20 Pseudonocardia strains will be generated, which will facilitate estimations of the degree of genome plasticity and rates and patterns of evolution in this group of bacteria. Symbiosis is a major theme in the history of life; thus, this work will contribute to understanding general mechanisms that drive biological complexity and diversity. The research team will contribute to education and training through the development of public displays related to this project for The Microbe Place in the Microbial Sciences Building at the University of Wisconsin-Madison, as well as through a yearly workshop on microbial genomics for undergraduate and graduate researchers.
