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Ascomycota is a
phylum
In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead ...
of the kingdom Fungi
A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
that, together with the Basidiomycota
Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...
, forms the subkingdom Dikarya
Dikarya is a subkingdom of Fungi that includes the divisions Ascomycota and Basidiomycota, both of which in general produce dikaryons, may be hypha, filamentous or unicellular, but are always without flagella. The Dikarya are most of the so-calle ...
. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
. The defining feature of this fungal group is the "ascus
An ascus (; : asci) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some gen ...
" (), a microscopic sexual structure in which nonmotile spore
In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...
s, called ascospore
In fungi, an ascospore is the sexual spore formed inside an ascus—the sac-like cell that defines the division Ascomycota, the largest and most diverse Division (botany), division of fungi. After two parental cell nucleus, nuclei fuse, the ascu ...
s, are formed. However, some species of Ascomycota are asexual
Asexual or Asexuals may refer to:
*Asexual reproduction
**Asexual reproduction in starfish
*Asexuality, the lack of sexual attraction to anyone or lack of interest in or desire for sexual activity.
**Gray asexuality, the spectrum between asexualit ...
and thus do not form asci or ascospores. Familiar examples of sac fungi include morels
''Morchella'', the true morels, is a genus of edible sac fungi closely related to anatomically simpler cup fungi in the order Pezizales ( division Ascomycota). These distinctive fungi have a honeycomb appearance due to the network of ridges w ...
, truffle
A truffle is the Sporocarp (fungi), fruiting body of a subterranean ascomycete fungus, one of the species of the genus ''Tuber (fungus), Tuber''. More than one hundred other genera of fungi are classified as truffles including ''Geopora'', ''P ...
s, brewers' and bakers' yeast
''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungal microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been o ...
, dead man's fingers, and cup fungi
The Pezizaceae (commonly referred to as cup fungi) are a family of fungi in the Ascomycota which produce mushrooms that tend to grow in the shape of a "cup". Spores are formed on the inner surface of the fruit body ( ascoma). The cup shape typi ...
. The fungal symbionts
Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term
The hypha that creates the sporing (conidiating) tip can be very similar to the normal hyphal tip, or it can be differentiated. The most common differentiation is the formation of a bottle shaped cell called a , from which the spores are produced. Not all of these asexual structures are a single hypha. In some groups, the conidiophores (the structures that bear the conidia) are aggregated to form a thick structure.
E.g. In the order ''Moniliales,'' all of them are single hyphae with the exception of the aggregations, termed as coremia or synnema. These produce structures rather like corn-stokes, with many conidia being produced in a mass from the aggregated conidiophores.
The diverse conidia and conidiophores sometimes develop in asexual sporocarps with different characteristics (e.g. acervulus, pycnidium, sporodochium). Some species of ascomycetes form their structures within plant tissue, either as parasite or saprophytes. These fungi have evolved more complex asexual sporing structures, probably influenced by the cultural conditions of plant tissue as a substrate. These structures are called the . This is a cushion of conidiophores created from a pseudoparenchymatous stroma in plant tissue. The is a globose to flask-shaped parenchymatous structure, lined on its inner wall with conidiophores. The is a flat saucer shaped bed of conidiophores produced under a plant cuticle, which eventually erupt through the cuticle for dispersal.
The initial events of budding can be seen as the development of a ring of chitin around the point where the bud is about to appear. This reinforces and stabilizes the cell wall. Enzymatic activity and turgor pressure act to weaken and extrude the cell wall. New cell wall material is incorporated during this phase. Cell contents are forced into the progeny cell, and as the final phase of mitosis ends a cell plate, the point at which a new cell wall will grow inwards from, forms.
Most species grow as filamentous, microscopic structures called 
In 
Large masses of yeast cells, asci or ascus-like cells, or conidia can also form macroscopic structures. For example. ''
lichen
A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...
s (loosely termed "ascolichens") such as ''Cladonia
''Cladonia'' is a genus of moss-like lichenized fungi in the family Cladoniaceae. They are the primary food source for reindeer/caribou. ''Cladonia'' species are of economic importance to reindeer-herders, such as the Sami in Scandinavia or th ...
'' belong to the Ascomycota.
Ascomycota is a monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
group (containing all of the descendants of a common ancestor). Previously placed in the Basidiomycota
Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...
along with asexual species from other fungal taxa, asexual (or anamorph
In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota:
*Teleomorph: the sexual reproductive stage (morph), typically a fruiting body.
*Anamorph: an ase ...
ic) ascomycetes are now identified and classified based on morphological or physiological
Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ syst ...
similarities to ascus-bearing taxa
In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
, and by phylogenetic
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
analyses of DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
sequences.
Ascomycetes are of particular use to humans as sources of medicinally important compounds such as antibiotics
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...
, as well as for fermenting
Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduced ...
bread, alcoholic beverages, and cheese. Examples of ascomycetes include ''Penicillium
''Penicillium'' () is a genus of Ascomycota, ascomycetous fungus, fungi that is part of the mycobiome of many species and is of major importance in the natural environment, in food spoilage, and in food and drug production.
Some members of th ...
'' species on cheeses and those producing antibiotics for treating bacterial infectious disease
An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...
s.
Many ascomycetes are pathogen
In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
s, both of animals, including humans, and of plants. Examples of ascomycetes that can cause infections in humans include ''Candida albicans
''Candida albicans'' is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usu ...
'', ''Aspergillus niger
''Aspergillus niger'' is a mold classified within the ''Nigri'' section of the ''Aspergillus'' genus. The ''Aspergillus'' genus consists of common molds found throughout the environment within soil and water, on vegetation, in fecal matter, on de ...
'' and several tens of species that cause skin infections
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different d ...
. The many plant-pathogenic ascomycetes include apple scab
Apple scab is a common disease of plants in the rose family (Rosaceae) that is caused by the ascomycete fungus ''Venturia inaequalis''. While this disease affects several plant genera, including '' Sorbus, Cotoneaster,'' and '' Pyrus'', it is ...
, rice blast
''Magnaporthe grisea'', also known as rice blast fungus, rice rotten neck, rice seedling blight, blast of rice, oval leaf spot of graminea, pitting disease, ryegrass blast, Johnson spot, neck blast, wheat blast and , is a plant-pathogenic fungus ...
, the ergot
Ergot ( ) or ergot fungi refers to a group of fungi of the genus ''Claviceps''.
The most prominent member of this group is '' Claviceps purpurea'' ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that c ...
fungi, black knot
''Dibotryon morbosum'' or ''Apiosporina morbosa'' is a plant pathogen, which is the causal agent of black knot. It affects members of the ''Prunus'' genus such as cherry, plum, apricot, and chokecherry trees in North America. The disease produce ...
, and the powdery mildew
Powdery mildew is a fungus, fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of Ascomycota, ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant disea ...
s. The members of the genus ''Cordyceps
''Cordyceps'' is a genus of ascomycete fungi (sac fungi) that includes over 260 species worldwide, many of which are parasitic. Diverse variants of cordyceps have had more than 1,500 years of use in Chinese medicine. Most ''Cordyceps'' specie ...
'' are entomopathogenic fungi
Entomopathogenic fungi are parasitic unicellular or multicellular microorganisms belonging to the kingdom of Fungi, that can infect and seriously disable or kill insects.
Pathogenicity for insects is widely distributed in the kingdom of fungi and ...
, meaning that they parasitise and kill insects. Other entomopathogenic ascomycetes have been used successfully in biological pest control
Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or ot ...
, such as ''Beauveria
''Beauveria'' is a genus of asexually-reproducing fungi allied with the ascomycete family Cordycipitaceae. Its several species are typically insect pathogens. The sexual states ( teleomorphs) of ''Beauveria'' species, where known, are species ...
''.
Several species of ascomycetes are biological model organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...
s in laboratory research. Most famously, ''Neurospora crassa
''Neurospora crassa'' is a type of red bread mold of the phylum Ascomycota. The genus name, meaning 'nerve spore' in Greek, refers to the characteristic striations on the spores. The first published account of this fungus was from an infestatio ...
'', several species of yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...
s, and ''Aspergillus
' () is a genus consisting of several hundred mold species found in various climates worldwide.
''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...
'' species are used in many genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...
and cell biology
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living an ...
studies.
Sexual reproduction in ascomycetes
Ascomycetes are 'spore shooters'. They are fungi which produce microscopic spores inside special, elongated cells or sacs, known as 'asci', which give the group its name. Asexual reproduction is the dominant form of propagation in the Ascomycota, and is responsible for the rapid spread of these fungi into new areas. Asexual reproduction of ascomycetes is very diverse from both structural and functional points of view. The most important and general is production of conidia, but chlamydospores are also frequently produced. Furthermore, Ascomycota also reproduce asexually through budding.Conidia formation
Asexual reproduction may occur through vegetative reproductive spores, theconidia
A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...
. The asexual, non-motile haploid spores of a fungus, which are named after the Greek word for dust (conia), are hence also known as . The conidiospores commonly contain one nucleus and are products of mitotic cell divisions and thus are sometimes called , which are genetically identical to the mycelium from which they originate. They are typically formed at the ends of specialized hyphae, the conidiophores. Depending on the species they may be dispersed by wind or water, or by animals. Conidiophores may simply branch off from the mycelia or they may be formed in fruiting bodies.
The hypha that creates the sporing (conidiating) tip can be very similar to the normal hyphal tip, or it can be differentiated. The most common differentiation is the formation of a bottle shaped cell called a , from which the spores are produced. Not all of these asexual structures are a single hypha. In some groups, the conidiophores (the structures that bear the conidia) are aggregated to form a thick structure.
E.g. In the order ''Moniliales,'' all of them are single hyphae with the exception of the aggregations, termed as coremia or synnema. These produce structures rather like corn-stokes, with many conidia being produced in a mass from the aggregated conidiophores.
The diverse conidia and conidiophores sometimes develop in asexual sporocarps with different characteristics (e.g. acervulus, pycnidium, sporodochium). Some species of ascomycetes form their structures within plant tissue, either as parasite or saprophytes. These fungi have evolved more complex asexual sporing structures, probably influenced by the cultural conditions of plant tissue as a substrate. These structures are called the . This is a cushion of conidiophores created from a pseudoparenchymatous stroma in plant tissue. The is a globose to flask-shaped parenchymatous structure, lined on its inner wall with conidiophores. The is a flat saucer shaped bed of conidiophores produced under a plant cuticle, which eventually erupt through the cuticle for dispersal.
Budding
Asexual reproduction process in ascomycetes also involves the budding which we clearly observe in yeast. This is termed a "blastic process". It involves the blowing out or blebbing of the hyphal tip wall. The blastic process can involve all wall layers, or there can be a new cell wall synthesized which is extruded from within the old wall.
The initial events of budding can be seen as the development of a ring of chitin around the point where the bud is about to appear. This reinforces and stabilizes the cell wall. Enzymatic activity and turgor pressure act to weaken and extrude the cell wall. New cell wall material is incorporated during this phase. Cell contents are forced into the progeny cell, and as the final phase of mitosis ends a cell plate, the point at which a new cell wall will grow inwards from, forms.
Characteristics of ascomycetes
* Ascomycota are morphologically diverse. The group includes organisms from unicellular yeasts to complex cup fungi. * 98% oflichens
A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...
have an Ascomycota as the fungal part of the lichen.
* There are 2000 identified genera and 30,000 species of Ascomycota.
* The unifying characteristic among these diverse groups is the presence of a reproductive structure known as the , though in some cases it has a reduced role in the life cycle.
* Many ascomycetes are of commercial importance. Some play a beneficial role, such as the yeasts used in baking, brewing, and wine fermentation, plus truffles and morels, which are held as gourmet delicacies.
* Many of them cause tree diseases, such as Dutch elm disease and apple blights.
* Some of the plant pathogenic ascomycetes are apple scab, rice blast, the ergot fungi, black knot, and the powdery mildews.
* The yeasts are used to produce alcoholic beverages and breads. The mold ''Penicillium'' is used to produce the antibiotic penicillin.
* Almost half of all members of the phylum Ascomycota form associations with algae to form lichens.
* Others, such as morels (a highly prized edible fungi), form important relationships with plants, thereby providing enhanced water and nutrient uptake and, in some cases, protection from insects.
* Most ascomycetes are terrestrial or parasitic. However, some have adapted to marine or freshwater environments. As of 2015, there were 805 marine fungi
Marine fungi are species of fungi that live in marine or estuarine environments. They are not a taxonomic group, but share a common habitat. Obligate marine fungi grow exclusively in the marine habitat while wholly or sporadically submerged in ...
in the Ascomycota, distributed among 352 genera.
* The cell walls of the hyphae are variably composed of chitin
Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cell ...
and β-glucans, just as in Basidiomycota. However, these fibers are set in a matrix of glycoprotein containing the sugars galactose and mannose.
* The mycelium of ascomycetes is usually made up of septate hyphae
A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium.
Structure
A hypha consists of one or ...
. However, there is not necessarily any fixed number of nuclei in each of the divisions.
* The septal walls have septal pores which provide cytoplasmic continuity throughout the individual hyphae. Under appropriate conditions, nuclei may also migrate between septal compartments through the septal pores.
* A unique character of the Ascomycota (but not present in all ascomycetes) is the presence of Woronin bodies on each side of the septa separating the hyphal segments which control the septal pores. If an adjoining hypha is ruptured, the Woronin bodies block the pores to prevent loss of cytoplasm into the ruptured compartment. The Woronin bodies are spherical, hexagonal, or rectangular membrane bound structures with a crystalline protein matrix.
Modern classification
There are threesubphyla
In zoological nomenclature, a subphylum is a taxonomic rank below the rank of phylum.
The taxonomic rank of " subdivision" in fungi and plant taxonomy is equivalent to "subphylum" in zoological taxonomy. Some plant taxonomists have also used the ...
that are described and accepted:
* The ''Pezizomycotina
Pezizomycotina is the largest subdivision of Ascomycota, containing the filamentous ascomycetes and most lichenized fungi. It is more or less synonymous with the older taxon Euascomycota. These fungi reproduce by fission rather than budding. Thi ...
'' are the largest subphylum and contains all ascomycetes that produce ascocarp
An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...
s (fruiting bodies), except for one genus, '' Neolecta'', in the Taphrinomycotina
The Taphrinomycotina are one of three subdivisions constituting the Ascomycota (fungi that form their spores in a sac-like ascus) and is more or less synonymous with the slightly older invalid name Archiascomycetes (sometimes spelled Archaeascomy ...
. It is roughly equivalent to the previous taxon, ''Euascomycetes''. The Pezizomycotina includes most macroscopic "ascos" such as truffle
A truffle is the Sporocarp (fungi), fruiting body of a subterranean ascomycete fungus, one of the species of the genus ''Tuber (fungus), Tuber''. More than one hundred other genera of fungi are classified as truffles including ''Geopora'', ''P ...
s, ergot
Ergot ( ) or ergot fungi refers to a group of fungi of the genus ''Claviceps''.
The most prominent member of this group is '' Claviceps purpurea'' ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that c ...
, ascolichens, cup fungi
The Pezizaceae (commonly referred to as cup fungi) are a family of fungi in the Ascomycota which produce mushrooms that tend to grow in the shape of a "cup". Spores are formed on the inner surface of the fruit body ( ascoma). The cup shape typi ...
(discomycetes
Discomycetes is a former taxonomic class of Ascomycete fungi which contains all of the cup, sponge and brain fungi, and some club-like fungi. It includes typical cup fungi like the scarlet elf cup and the orange peel fungus, and fungi with frui ...
), pyrenomycetes
Sordariomycetes is a class of fungi in the subdivision Pezizomycotina (Ascomycota). It is the second-largest class of Ascomycota, with a worldwide distribution that mostly accommodates terrestrial based taxa, although several can also be found in ...
, lorchels, and caterpillar fungus. It also contains microscopic fungi such as powdery mildew
Powdery mildew is a fungus, fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of Ascomycota, ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant disea ...
s, dermatophytic
Dermatophyte (from Greek '' derma'' "skin" ( GEN ''dermatos'') and ''phyton'' "plant") is a common label for a group of fungus of ''Arthrodermataceae'' that commonly causes skin disease in animals and humans. Traditionally, these anamorphic (a ...
fungi, and Laboulbeniales
The Laboulbeniales is an order of fungi within the class Laboulbeniomycetes. They are also known by the colloquial name beetle hangers or labouls. The order includes around 2,325 species of obligate insect ectoparasites that produce cellular ...
.
* The ''Saccharomycotina
Saccharomycotina is a subdivision (subphylum) of the division (phylum) Ascomycota in the kingdom Fungi. It comprises most of the ascomycete yeasts. The members of Saccharomycotina reproduce by budding and they do not produce ascocarps (fruiting ...
'' comprise most of the "true" yeasts, such as baker's yeast
Baker's yeast is the common name for the strains of yeast commonly used in baking bread and other bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable ...
and ''Candida
Candida, or Cándida (Spanish), may refer to:
Biology and medicine
* ''Candida'' (fungus), a genus of yeasts
** Candidiasis, an infection by ''Candida'' organisms
* Malvasia Candida, a variety of grape
Places
* Candida, Campania, a ''comu ...
'', which are single-celled (unicellular) fungi, which reproduce vegetatively by budding. Most of these species were previously classified in a taxon called ''Hemiascomycetes''.
* The ''Taphrinomycotina
The Taphrinomycotina are one of three subdivisions constituting the Ascomycota (fungi that form their spores in a sac-like ascus) and is more or less synonymous with the slightly older invalid name Archiascomycetes (sometimes spelled Archaeascomy ...
'' include a disparate and basal group within the Ascomycota that was recognized following molecular (DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
) analyses. The taxon was originally named '' Archiascomycetes'' (or '' Archaeascomycetes''). It includes hyphal fungi ('' Neolecta'', ''Taphrina
''Taphrina'' is a fungal genus within the Ascomycota that causes leaf and catkin curl diseases and witch's brooms of certain flowering plants. One of the more commonly observed species causes peach leaf curl. ''Taphrina'' typically grow as yeas ...
'', ''Archaeorhizomyces
Archaeorhizomycetes is a class of fungi in the subdivision Taphrinomycotina of the Ascomycota. So far, the class has only one described order, Archaeorhizomycetales, family, Archaeorhizomycetaceae, and genus, ''Archaeorhizomyces''. The class was ...
''), fission yeasts (''Schizosaccharomyces
''Schizosaccharomyces'' is a genus of fission yeasts. The most well-studied species is '' S. pombe''. At present five Schizosaccharomyces species have been described ('' S. pombe'', ''S. japonicus'', ''S. octosporus'', ''S. cryophilus'' and ''S ...
''), and the mammalian lung parasite ''Pneumocystis
The Pneumocystidomycetes are a class of ascomycete fungi. It includes the single order Pneumocystidales, which contains the single monotypic family Pneumocystidaceae, which in turn contains the genus
Genus (; : genera ) is a taxonomic rank ...
''.
Outdated taxon names
Several outdated taxon names—based on morphological features—are still occasionally used for species of the Ascomycota. These include the following sexual (teleomorph
In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota:
*Teleomorph: the sexual reproductive stage (morph), typically a fruiting body.
*Anamorph: an ase ...
ic) groups, defined by the structures of their sexual fruiting bodies
The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cyc ...
: the Discomycetes
Discomycetes is a former taxonomic class of Ascomycete fungi which contains all of the cup, sponge and brain fungi, and some club-like fungi. It includes typical cup fungi like the scarlet elf cup and the orange peel fungus, and fungi with frui ...
, which included all species forming apothecia
An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. As ...
; the Pyrenomycetes
Sordariomycetes is a class of fungi in the subdivision Pezizomycotina (Ascomycota). It is the second-largest class of Ascomycota, with a worldwide distribution that mostly accommodates terrestrial based taxa, although several can also be found in ...
, which included all sac fungi that formed perithecia
An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...
or pseudothecia
An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...
, or any structure resembling these morphological structures; and the Plectomycetes, which included those species that form cleistothecia
An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...
. Hemiascomycetes included the yeasts and yeast-like fungi that have now been placed into the Saccharomycotina
Saccharomycotina is a subdivision (subphylum) of the division (phylum) Ascomycota in the kingdom Fungi. It comprises most of the ascomycete yeasts. The members of Saccharomycotina reproduce by budding and they do not produce ascocarps (fruiting ...
or Taphrinomycotina
The Taphrinomycotina are one of three subdivisions constituting the Ascomycota (fungi that form their spores in a sac-like ascus) and is more or less synonymous with the slightly older invalid name Archiascomycetes (sometimes spelled Archaeascomy ...
, while the Euascomycetes included the remaining species of the Ascomycota, which are now in the Pezizomycotina
Pezizomycotina is the largest subdivision of Ascomycota, containing the filamentous ascomycetes and most lichenized fungi. It is more or less synonymous with the older taxon Euascomycota. These fungi reproduce by fission rather than budding. Thi ...
, and the Neolecta, which are in the Taphrinomycotina.
Some ascomycetes do not reproduce sexually or are not known to produce asci and are therefore anamorph
In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota:
*Teleomorph: the sexual reproductive stage (morph), typically a fruiting body.
*Anamorph: an ase ...
ic species. Those anamorphs that produce conidia
A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...
(mitospores) were previously described as mitosporic Ascomycota
The mitosporic Ascomycota are a heterogeneous group of ascomycotic fungi whose common characteristic is the absence of a sexual state ( anamorph); many of the pathogenic fungi in humans belong to this group.
*'' Acremonium''
*'' Acrodontium''
*'' ...
. Some taxonomists placed this group into a separate artificial phylum, the Deuteromycota (or "Fungi Imperfecti"). Where recent molecular analyses have identified close relationships with ascus-bearing taxa, anamorphic species have been grouped into the Ascomycota, despite the absence of the defining ascus. Sexual and asexual isolates of the same species commonly carry different binomial
Binomial may refer to:
In mathematics
*Binomial (polynomial), a polynomial with two terms
*Binomial coefficient, numbers appearing in the expansions of powers of binomials
*Binomial QMF, a perfect-reconstruction orthogonal wavelet decomposition
* ...
species names, as, for example, ''Aspergillus nidulans
''Aspergillus nidulans'' (also called '' Emericella nidulans'' when referring to its sexual form, or teleomorph) is one of many species of filamentous fungi in the phylum Ascomycota. It has been an important research organism for studying eukary ...
'' and ''Emericella nidulans'', for asexual and sexual isolates, respectively, of the same species.
Species of the Deuteromycota were classified as Coelomycetes if they produced their conidia in minute flask- or saucer-shaped conidiomata, known technically as ''pycnidia'' and ''acervuli''. The Hyphomycetes
Hyphomycetes are a form classification of fungi, part of what has often been referred to as fungi imperfecti, Deuteromycota, or anamorphic fungi. Hyphomycetes lack closed fruit bodies, and are often referred to as moulds (or molds). Most hypho ...
were those species where the conidiophore
A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an Asexual reproduction, asexual, non-motility, motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word f ...
s (''i.e.'', the hyphal structures that carry conidia-forming cells at the end) are free or loosely organized. They are mostly isolated but sometimes also appear as bundles of cells aligned in parallel (described as ''synnematal'') or as cushion-shaped masses (described as ''sporodochial'').
Morphology
Most species grow as filamentous, microscopic structures called hypha
A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium.
Structure
A hypha consists of one o ...
e or as budding single cells (yeasts). Many interconnected hyphae form a thallus
Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entir ...
usually referred to as the mycelium
Mycelium (: mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are fo ...
, which—when visible to the naked eye (macroscopic)—is commonly called mold
A mold () or mould () is one of the structures that certain fungus, fungi can form. The dust-like, colored appearance of molds is due to the formation of Spore#Fungi, spores containing Secondary metabolite#Fungal secondary metabolites, fungal ...
. During sexual reproduction, many Ascomycota typically produce large numbers of asci. The ascus is often contained in a multicellular, occasionally readily visible fruiting structure, the ascocarp
An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...
(also called an ''ascoma''). Ascocarps come in a very large variety of shapes: cup-shaped, club-shaped, potato-like, spongy, seed-like, oozing and pimple-like, coral-like, nit-like, golf-ball-shaped, perforated tennis ball-like, cushion-shaped, plated and feathered in miniature (Laboulbeniales
The Laboulbeniales is an order of fungi within the class Laboulbeniomycetes. They are also known by the colloquial name beetle hangers or labouls. The order includes around 2,325 species of obligate insect ectoparasites that produce cellular ...
), microscopic classic Greek shield-shaped, stalked or sessile. They can appear solitary or clustered. Their texture can likewise be very variable, including fleshy, like charcoal (carbonaceous), leathery, rubbery, gelatinous, slimy, powdery, or cob-web-like. Ascocarps come in multiple colors such as red, orange, yellow, brown, black, or, more rarely, green or blue. Some ascomyceous fungi, such as ''Saccharomyces cerevisiae'', grow as single-celled yeasts, which—during sexual reproduction—develop into an ascus, and do not form fruiting bodies.
In lichen
A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...
ized species, the thallus of the fungus defines the shape of the symbiotic
Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...
colony. Some dimorphic species, such as ''Candida albicans
''Candida albicans'' is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usu ...
'', can switch between growth as single cells and as filamentous, multicellular hyphae. Other species are pleomorphic, exhibiting asexual (anamorphic) as well as a sexual (teleomorphic) growth forms.
Except for lichens, the non-reproductive (vegetative) mycelium of most ascomycetes is usually inconspicuous because it is commonly embedded in the substrate, such as soil, or grows on or inside a living host, and only the ascoma may be seen when fruiting. Pigment
A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...
ation, such as melanin
Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes.
There are ...
in hyphal walls, along with prolific growth on surfaces can result in visible mold colonies; examples include ''Cladosporium
''Cladosporium'' is a genus of fungi including some of the most common indoor and outdoor molds. Some species are endophytes or plant pathogens, while others parasitize fungi.
Description
Species produce olive-green to brown or black colonie ...
'' species, which form black spots on bathroom caulking and other moist areas. Many ascomycetes cause food spoilage, and, therefore, the pellicles or moldy layers that develop on jams, juices, and other foods are the mycelia of these species or occasionally Mucoromycotina
Mucoromycotina is a subphylum of uncertain placement in Fungi. It was considered part of the phylum Zygomycota, but recent phylogenetic studies have shown that it was polyphyletic and thus split into several groups, it is now thought to be a para ...
and almost never Basidiomycota
Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...
. Sooty mold
Sooty mold (also spelled sooty mould) is a collective term for different Ascomycete fungi, which includes many genera, commonly ''Cladosporium'' and ''Alternaria''. It grows on plants and their fruit, but also environmental objects, like fences, ...
s that develop on plants, especially in the tropics are the thalli of many species.
Large masses of yeast cells, asci or ascus-like cells, or conidia can also form macroscopic structures. For example. ''Pneumocystis
The Pneumocystidomycetes are a class of ascomycete fungi. It includes the single order Pneumocystidales, which contains the single monotypic family Pneumocystidaceae, which in turn contains the genus
Genus (; : genera ) is a taxonomic rank ...
'' species can colonize lung cavities (visible in x-rays), causing a form of pneumonia
Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...
. Asci of ''Ascosphaera
''Ascosphaera'' is a genus of fungi in the family Ascosphaeraceae. It was described in 1955 by mycologists Charles F. Spiltoir and Lindsay S. Olive. Members of the genus are insect pathogens. The type species, '' A. apis'', causes chalkbro ...
'' fill honey bee
A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to mainland Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the ...
larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
e and pupa
A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...
e causing mummification with a chalk-like appearance, hence the name "chalkbrood". Yeasts for small colonies in vitro
''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...
and in vivo
Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, an ...
, and excessive growth of ''Candida
Candida, or Cándida (Spanish), may refer to:
Biology and medicine
* ''Candida'' (fungus), a genus of yeasts
** Candidiasis, an infection by ''Candida'' organisms
* Malvasia Candida, a variety of grape
Places
* Candida, Campania, a ''comu ...
'' species in the mouth or vagina causes "thrush", a form of candidiasis
Candidiasis is a fungal infection due to any species of the genus '' Candida'' (a yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the ...
.
The cell walls of the ascomycetes almost always contain chitin
Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cell ...
and β-glucans, and divisions within the hyphae, called "septa
SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...
", are the internal boundaries of individual cells (or compartments). The cell wall and septa give stability and rigidity to the hyphae and may prevent loss of cytoplasm
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...
in case of local damage to cell wall and cell membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...
. The septa commonly have a small opening in the center, which functions as a cytoplasm
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...
ic connection between adjacent cells, also sometimes allowing cell-to-cell movement of nuclei within a hypha. Vegetative hyphae of most ascomycetes contain only one nucleus per cell (''uninucleate
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