ABSTRACT
Ascomycota is the largest phylum in the kingdom Fungi and contains over 65,000 species, which constitutes 66% of all known fungal species (Kirk et al., 2008). The unifying diagnostic characteristic of species in Ascomycota is the ascus, a sac-like structure containing ascospores that resulted from sexual reproduction and meiosis (Figures 13.1 and 13.2). Asci and sometimes paraphyses (sterile hyphae) typically originate from the hymenium, which is termed the fertile layer in the fruiting body. Based on molecular phylogenetic analyses and morphology, Ascomycota is divided into the following three subphyla (Figure 13.3): Taphrinomycotina (“Archiascomycetes”), Saccharomycotina (Chapter 11), and the Pezizomycotina (“Ascomycotina”). Most members of the first two subphyla are yeasts or yeast-like organisms. This chapter focuses on Pezizomycotina (excluding the powdery mildews: Chapter 12), which are the filamentous ascomycetes that constitute the majority of Ascomycota, and their
asexual reproductive modes that have been treated previously as “Deuteromycetes” or “mitosporic fungi.” We no longer use the two former classification schemes for conidial forms of Ascomycetes and, instead, treat them as asexual forms of species in Ascomycota. This change of classification systems will be explored in more detail in subsequent paragraphs.
