Establishment of Cell Identity in Pathogenic Fungi

Abstract

This chapter examines how cell identity influences mating-type determination, particularly in fungal pathogens. It explores cases where cell identity plays roles outside of mating type, affects cell morphology, and influences pathogenesis. The chapter begins with a description of cell type determination in the budding yeast Saccharomyces cerevisiae and uses this as a platform for exploring mechanisms in the human fungal pathogens Candida albicans and Cryptococcus neoformans as well as the plant fungal pathogen Ustilago maydis. It concludes with a short description of the influence of cell identity on the behaviors of several other plant and human fungal pathogens and how cell identity in fungi is evolving to encompass a more diverse array of fungal behaviors. A fungal pathogen in which cell identity determination has come to the fore is in the basidiomycete fungus C. neoformans. There are two obvious possibilities for specifying haploid cell identity: either the pheromone and pheromone receptor alleles in each mating type have diverged from one another sufficiently to confer pheromone-receptor binding specificity, or there are other factors or mechanisms at play in determining haploid cell types. The authors will continue to discover new strategies undertaken by the pathogenic fungi to develop and integrate multiple cell identities in the effort to survive.