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Ascomycota
Ascomycota is a division or phylum of the kingdom Fungi that, together with the Basidiomycota, form the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. They are the largest phylum of Fungi, with over 64,000 species.〔Kirk ''et al''., p. 55.〕 The defining feature of this fungal group is the "ascus" (from Greek: (''askos''), meaning "sac" or "wineskin"), a microscopic sexual structure in which nonmotile spores, called ascospores, are formed. However, some species of the Ascomycota are asexual, meaning that they do not have a sexual cycle and thus do not form asci or ascospores. Previously placed in the Deuteromycota along with asexual species from other fungal taxa, asexual (or anamorphic) ascomycetes are now identified and classified based on morphological or physiological similarities to ascus-bearing taxa, and by phylogenetic analyses of DNA sequences.
The ascomycetes are a monophyletic group, i.e. it contains all descendants of one common ancestor. This group is of particular relevance to humans as sources for medicinally important compounds, such as antibiotics and for making bread, alcoholic beverages, and cheese, but also as pathogens of humans and plants. Familiar examples of sac fungi include morels, truffles, brewer's yeast and baker's yeast, dead man's fingers, and cup fungi. The fungal symbionts in the majority of lichens (loosely termed "ascolichens") such as ''Cladonia'' belong to the Ascomycota. There are many plant-pathogenic ascomycetes, including apple scab, rice blast, the ergot fungi, black knot, and the powdery mildews. Several species of ascomycetes are biological model organisms in laboratory research. Most famously, ''Neurospora crassa'', several species of yeasts, and ''Aspergillus'' species are used in many genetics and cell biology studies. ''Penicillium'' species on cheeses and those producing antibiotics for treating bacterial infectious diseases are examples of taxa that belong to the Ascomycota.
== Ascomycetes versus Ascomycota ==
Before the recognition of the fungal kingdom, the sac fungi were considered to be a ''class'', not a ''phylum''. The original collective term for these taxa was "Ascomycetes", which was first coined in the 1800s for a rankless nonlichenized taxon that possessed asci. The names Ascomycota, Ascomycetes, and others with the same root are based upon the term "ascus". "Ascomycetes" was soon used to include lichenized taxa, and became the standard term, at the class level, for all ascus-bearing species, just as the term "Basidiomycetes" became used for their basidium-bearing counterparts. Elevation of the taxonomic rank of the Ascomycetes resulted in the names Ascomycetae, Ascomycotina, and finally Ascomycota. Together, the Ascomycota and the Basidiomycota form the subkingdom Dikarya. The more familiar term, Ascomycetes, is still loosely used, e.g. at fungal forays it is often said of a fungus, such as ''Peziza'', "It is an ascomycete, not a basidiomycete" in reference to their sexual reproductive mode. The terms are further abbreviated to "ascos" and "basidos", which are not officially sanctioned technical names.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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