Discovery of attributes that distinguish pathogens from non pathogens and symbionts from pathogens or non-pathogens is the focus of contemporary research in plant pathology and an overall goal of our work. This endeavor overlaps with our study of fungal reproductive strategies, since both are fundamentally recognition issues. For pathogenic, symbiotic, or mutualistic associations, the issue is how cells of different organisms (e.g., a fungus and its plant host) communicate with each other to effect their partnership or cause disease; for reproduction, the question is how cells (or nuclei) of the same organism recognize self from non-self. Both forms of recognition allow one cell to form an intimate association, or to fuse with, another. Of practical importance, is the fact that fungi travel in the field by spore dissemination, thus, complete understanding of the spore developmental pathway provides an avenue for design of global solutions for preventing plant disease. We apply a wide range of classical genetic, molecular genetic, genomic, biochemical, and cytological tools and use three model fungi, Cochliobolus heterostrophus, a necrotrophic pathogen of corn, Setosphaeria turcica, a hemibiotrophic pathogen of corn, and Fusarium graminearum/Gibberella zeae, a necrotrophic pathogen of wheat, corn, barley and rice to address our questions