Pezizomycotina make up the majority of the Ascomycota fungi and include most lichenized fungi too. Pezizomycotina contains the filamentous is a subdivision of the Ascomycota, it is less synonymous with the older taxon Euascomycota. These fungi reproduce by fission rather than budding and this subdivision includes all the ascus fungi that have fruiting bodies visible to the naked eye. See the taxobox for a list of the classes that make up the Pezizomycotina; the old class Loculoascomycetes has been replaced by the two classes Eurotiomycetes and Dothideomycetes. The rest of the Pezizomycotina include the defined hymenial groups Discomycetes and Pyrenomycetes; some important groups in Pezizomycotina include: Pezizomycetes, Laboulbeniomycetes, Dothideomycetes. Paleopyrenomycites from the Early Devonian Rhynie Chert is the oldest known fossil member of Pezizomycotina, although its position within this subdivision is unclear. Tree of Life Pezizomycotina The Pezizomycotina in the Paleos site
In zoological nomenclature, a type species is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e. the species that contains the biological type specimen. A similar concept is used for suprageneric groups called a type genus. In botanical nomenclature, these terms have no formal standing under the code of nomenclature, but are sometimes borrowed from zoological nomenclature. In botany, the type of a genus name is a specimen, the type of a species name; the species name that has that type can be referred to as the type of the genus name. Names of genus and family ranks, the various subdivisions of those ranks, some higher-rank names based on genus names, have such types. In bacteriology, a type species is assigned for each genus; every named genus or subgenus in zoology, whether or not recognized as valid, is theoretically associated with a type species. In practice, there is a backlog of untypified names defined in older publications when it was not required to specify a type.
A type species is both a concept and a practical system, used in the classification and nomenclature of animals. The "type species" represents the reference species and thus "definition" for a particular genus name. Whenever a taxon containing multiple species must be divided into more than one genus, the type species automatically assigns the name of the original taxon to one of the resulting new taxa, the one that includes the type species; the term "type species" is regulated in zoological nomenclature by article 42.3 of the International Code of Zoological Nomenclature, which defines a type species as the name-bearing type of the name of a genus or subgenus. In the Glossary, type species is defined as The nominal species, the name-bearing type of a nominal genus or subgenus; the type species permanently attaches a formal name to a genus by providing just one species within that genus to which the genus name is permanently linked. The species name in turn is fixed, to a type specimen. For example, the type species for the land snail genus Monacha is Helix cartusiana, the name under which the species was first described, known as Monacha cartusiana when placed in the genus Monacha.
That genus is placed within the family Hygromiidae. The type genus for that family is the genus Hygromia; the concept of the type species in zoology was introduced by Pierre André Latreille. The International Code of Zoological Nomenclature states that the original name of the type species should always be cited, it gives an example in Article 67.1. Astacus marinus Fabricius, 1775 was designated as the type species of the genus Homarus, thus giving it the name Homarus marinus. However, the type species of Homarus should always be cited using its original name, i.e. Astacus marinus Fabricius, 1775. Although the International Code of Nomenclature for algae and plants does not contain the same explicit statement, examples make it clear that the original name is used, so that the "type species" of a genus name need not have a name within that genus, thus in Article 10, Ex. 3, the type of the genus name Elodes is quoted as the type of the species name Hypericum aegypticum, not as the type of the species name Elodes aegyptica.
Glossary of scientific naming Genetypes – genetic sequence data from type specimens. Holotype Paratype Principle of Typification Type Type genus
Rhytisma punctatum is a species of fungus in the family Rhytismataceae. The fungus causes speckled tar spot of maple leaves; the small spots are black, raised from the leaf surface, occur in dense groups on the upper surface. Areas afflicted by the fungus will retain their color after the remainder of the leaf has faded. Rhytisma punctatum in Index Fungorum
The Leotiomycetes are a class of ascomycete fungi. Many of them cause serious plant diseases; the class Leotiomycetes contains numerous species with an anamorph placed within the fungi imperfecti, that have only found their place in the phylogenetic system. The older classifications placed Leotiomycetes into the Discomycetes clade. Molecular studies have shed some new light to the still obscure systematics. Most scholars consider Leotiomycetes a sister taxon to Sordariomycetes in the phylogenetic tree of Pezizomycotina, its division into subclasses have received strong support by the molecular data, but the overall monophyly of Leotiomycetes is dubious. Most Leotiomycetes grow their asci in apothecia; the asci are cylindrical, without operculum. The spores are hyaline, of various shapes, are released through a circular apical pore. Tree of Life: Leotiomycetes
In the fields of horticulture and botany, the term deciduous means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves in the autumn. The term deciduous means "the dropping of a part, no longer needed" and the "falling away after its purpose is finished". In plants, it is the result of natural processes. "Deciduous" has a similar meaning when referring to animal parts, such as deciduous antlers in deer, deciduous teeth in some mammals. Wood from deciduous trees is used in a variety of ways in several industries including lumber for furniture and flooring, bowling pins and baseball bats and furniture, cabinets and paneling. In botany and horticulture, deciduous plants, including trees and herbaceous perennials, are those that lose all of their leaves for part of the year; this process is called abscission. In some cases leaf loss coincides with winter -- namely in polar climates. In other parts of the world, including tropical and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall.
The converse of deciduous is evergreen, where foliage is shed on a different schedule from deciduous trees, therefore appearing to remain green year round. Plants that are intermediate may be called semi-deciduous. Other plants are semi-evergreen and lose their leaves before the next growing season, retaining some during winter or dry periods; some trees, including a few species of oak, have desiccated leaves that remain on the tree through winter. Many deciduous plants flower during the period when they are leafless, as this increases the effectiveness of pollination; the absence of leaves improves wind transmission of pollen for wind-pollinated plants and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost or, in dry season regions, result in water stress on the plant. There is much less branch and trunk breakage from glaze ice storms when leafless, plants can reduce water loss due to the reduction in availability of liquid water during cold winter days.
Leaf drop or abscission involves complex physiological changes within plants. The process of photosynthesis degrades the supply of chlorophylls in foliage; when autumn arrives and the days are shorter or when plants are drought-stressed, deciduous trees decrease chlorophyll pigment production, allowing other pigments present in the leaf to become apparent, resulting in non-green colored foliage. The brightest leaf colors are produced when days grow short and nights are cool, but remain above freezing; these other pigments include carotenoids that are yellow and orange. Anthocyanin pigments produce red and purple colors, though they are not always present in the leaves. Rather, they are produced in the foliage in late summer, when sugars are trapped in the leaves after the process of abscission begins. Parts of the world that have showy displays of bright autumn colors are limited to locations where days become short and nights are cool. In other parts of the world, the leaves of deciduous trees fall off without turning the bright colors produced from the accumulation of anthocyanin pigments.
The beginnings of leaf drop starts when an abscission layer is formed between the leaf petiole and the stem. This layer is formed in the spring during active new growth of the leaf; the cells are sensitive to a plant hormone called auxin, produced by the leaf and other parts of the plant. When auxin coming from the leaf is produced at a rate consistent with that from the body of the plant, the cells of the abscission layer remain connected; the elongation of these cells break the connection between the different cell layers, allowing the leaf to break away from the plant. It forms a layer that seals the break, so the plant does not lose sap. A number of deciduous plants remove nitrogen and carbon from the foliage before they are shed and store them in the form of proteins in the vacuoles of parenchyma cells in the roots and the inner bark. In the spring, these proteins are used as a nitrogen source during the growth of new leaves or flowers. Plants with deciduous foliage have advantages and disadvantages compared to plants with evergreen foliage.
Since deciduous plants lose their leaves to conserve water or to better survive winter weather conditions, they must regrow new foliage during the next suitable growing season. Evergreens suffer greater water loss during the winter and they can experience greater predation pressure when small. Losing leaves in winter may reduce damage from insects. Removing leaves reduces cavitation which can damage xylem vessels in plants; this allows deciduous plants to have xylem vessels with larger diameters and therefore a greater rate of transpiration during the summer growth period
Rhytisma acerinum is a plant pathogen that affects sycamores and maples in late summer and autumn, causing tar spot. Tar spot does not have an adverse effect on the trees' long-term health. R. acerinum is an Ascomycete fungus that locally infects the leaves of trees and is a biotrophic parasite. The disease is cosmetic and is therefore controlled only with sanitation methods. In late spring, chlorotic spots appear on tree leaves; these develop into brown-black lesions. The lesions continue to grow, by the end of summer form leaf spots that look like tar; the spot can grow up to 1.5 inches in diameter. A microscopic sign of the pathogen are mats of hyphae found in the lesions; these lesions can cause senescence of leaves but are of cosmetic importance. Rhytisma acerinum can occur in many tree species, with the most affected genus being Acer. Specific varieties affected most by the disease are Norway maple, silver maple and sycamore maple. · Rhytisma acerinum is the teleomorph of tar spot. In the spring, needle-shaped ascospores are released from overwintering apothecia in fallen leaf debris.
These spores have a sticky coat to attach to new healthy leaves. Once on the leaves, the spores penetrate through the stoma; the subsequent infection causes chlorosis of the leaves in localized yellow spots. As the season continues into summer, apothecia begin to form, giving rise to brown-black leaf lesions that resemble spots of tar. Leaves retain their yellow border from the initial chlorosis. Apothecia survive in the fallen plant debris over winter, releasing spores when the temperature is warm again; the infection of Tar Spot is localized to the chlorotic areas on the leaves and is a cosmetic issue, rather than an economically detrimental disease. The anamorph of tar spot is Melasmia acerina. In late summer, conidiophores are formed in the mass of fungal tissue called the stroma. Stroma is located in the black lesions of the infected leaves. Conidiophores form non-infectious conidia that are released both in conditions of wetness and drought; the most favorable environment for the pathogen is when there is an extended period of moisture such as fog or rain, which prevents the leaves from drying out.
Young trees growing in shade are therefore more susceptible. Under these conditions, conidiophores excrete a milky substance of conidia. In times of drought, the conidia stick together as one form yellowish tendrils; because the conidia are not infectious, this stage is not seen as as the teleomorph, it is not certain why the spores are produced. Tar spot is most found in Europe and North America, it was thought to be a useful pollution indicator because it is not found in areas with high amounts of sulfur dioxide. However, while sulfur dioxide is toxic to the fungus in laboratory studies, no correlation was found between pollution levels and the disease. Instead, it was found that in urban areas fallen leaves were more to be swept up and removed, thus removing a source of infection for the plants As mentioned the disease appears in the summer in times of wetness, but can develop through a dryer season. Tar spot is a localized disease that causes cosmetic symptoms and is therefore not a controlled disease.
One of the best ways to manage the pathogen is through proper sanitation techniques. Because the fungus overwinters in diseased leaf debris, removing the debris in fall can help reduce the occurrence of the disease. In certain severe cases, fungicides can be implemented to help with control. Copper fungicides sprayed in early spring when leaves are budding and twice more throughout the season to help reduce the disease. However, chemical control is not used because this disease is cosmetic. Resistant varieties are unknown; because the affected tree species are of low economic value, yield reduction is of little concern to growers. By far the most important practice is to remove as much debris as possible. Tar spot has been recognized since 1794, when it was discovered in Europe by Christiaan Hendrik Persoon, a prominent mycologist of that time. Tar spot has little historical importance because of its cosmetic nature. However, equine atypical myopathy has been associated with the ingestion of tar spot infected maple leaves.
This disease causes subsequent death in horses. Commentary and video of Tar Spot
Ascomycota is a division or phylum of the kingdom Fungi that, together with the Basidiomycota, form the subkingdom Dikarya. Its members are known as the sac fungi or ascomycetes, it is the largest phylum of Fungi, with over 64,000 species. The defining feature of this fungal group is the "ascus", 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. Familiar examples of sac fungi include morels, brewer's yeast and baker's yeast, dead man's fingers, cup fungi; the fungal symbionts in the majority of lichens such as Cladonia belong to the Ascomycota. Ascomycota is a monophyletic group. Placed in the Deuteromycota along with asexual species from other fungal taxa, asexual ascomycetes are now identified and classified based on morphological or physiological similarities to ascus-bearing taxa, by phylogenetic analyses of DNA sequences.
The ascomycetes are of particular use to humans as sources of medicinally important compounds, such as antibiotics, for fermenting bread, alcoholic beverages and cheese. Penicillium species on cheeses and those producing antibiotics for treating bacterial infectious diseases are examples of ascomycetes. Many ascomycetes are pathogens, both of animals, including humans, of plants. Examples of ascomycetes that can cause infections in humans include Candida albicans, Aspergillus niger and several tens of species that cause skin infections; the many plant-pathogenic ascomycetes include apple scab, rice blast, the ergot fungi, black knot, the powdery mildews. Several species of ascomycetes are biological model organisms in laboratory research. Most famously, Neurospora crassa, several species of yeasts, Aspergillus species are used in many genetics and cell biology studies. 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: Asexual reproduction is the dominant form of propagation in the Ascomycota, is responsible for the rapid spread of these fungi into new areas. Asexual reproduction of ascomycetes is diverse from both structural and functional points of view; the most important and general is production of conidia, but chlamydospores are frequently produced. Furthermore, Ascomycota reproduce asexually through budding. 1) Conidia formation: Asexual reproduction may occur through vegetative reproductive spores, the conidia. The asexual, non-motile haploid spores of a fungus, which are named after the Greek word for dust, are hence known as conidiospores and mitospores; the conidiospores contain one nucleus and are products of mitotic cell divisions and thus are sometimes call mitospores, which are genetically identical to the mycelium from which they originate. They are formed at the ends of specialized hyphae, the conidiophores. Depending on the species they may be dispersed by animals. Conidiophores may branch off from the mycelia or they may be formed in fruiting bodies.
The hypha that creates the sporing tip can be 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 phialide, from which the spores are produced. Not all of these asexual structures are a single hypha. In some groups, the conidiophores 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; some species of Ascomycetes form their structures within plant tissue, either as parasite or saprophytes. These fungi have evolved more complex asexual sporing structures influenced by the cultural conditions of plant tissue as a substrate; these structures are called the sporodochium.
This is a cushion of conidiophores created from a pseudoparenchymatous stroma in plant tissue. The pycnidium is a globose to flask-shaped parenchymatous structure, lined on its inner wall with conidiophores; the acervulus is a flat saucer shaped bed of conidiophores produced under a plant cuticle, which erupt through the cuticle for dispersal. 2) Budding: Asexual reproduction process in ascomycetes involves the budding which we observe in yeast. This is termed a “blastic process”, it involves the blebbing of the hyphal tip wall. The blastic process can involve all wall layers, or there can be a new cell wall synthesized, 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 stabilizes the cell wall. Enzymatic activity and turgor pressure act to extrude the cell wall. New cell wall material is incorporated during this phase. Cell contents are forced into the progeny cell, as the final phase of mitosis ends a cell plate, the point at which a new cell wall will grow inwards from, forms.
Ascomycota are morphologically diverse. The group includes organisms from unicellular yeasts to complex cup fungi. There are 30,000 species of Ascomycota; the unifying characteri