Pucciniomycotina Ustilaginomycotina Agaricomycotina Incertae sedis no phylum. Basidiomycota is a major division or phyla of the kingdom Fungiwhose members typically are characterized by the presence of a basidium, a microscopic reproductive structure where sexual spores are produced.
The presence of basidia "little pedestal" is one of the main diagnostic features of the Basidiomycota and is the source of the group's name. However, Basidiomycota also includes single-celled forms yeasts and asexual species.
Basidiomycota commonly are known as club fungigiven the club-shaped basidium. They also are known as basidiomycetes based on some older classifications that recognize Basidiomycetes as a class-level taxon ITIS About 30, described species are placed within Basidiomycota, or about 37 percent of all described species of fungi Swann and Hibbett Basidiomycota is so varied that unique morphological features of the group, such as basidium, dikaryon, and clamp connections, are not found in all representatives see description of Basidomycota.
Well-known Basidiomycota include rusts, smuts, various yeasts, true mushrooms, jelly fungi, false truffles, puffballs, stinkhorns. Basidiomycota are very important for the ecosystem and for humans. Ecologicallythey are vital for decaying dead organic matter, including wood and leaf litter, and thus vital for the carbon cycle Swann and Hibbett Some are cultivated by ants.
For humans, some Basidiomycota are a source of food. On the other hand, Basidiomycetes asexual reproduction definition also will decompose living wood tissue and thus can damage the wood in homes and other buildings, and the rusts and smuts are parasitic on plants and cause diseases of important agricultural crops, such as wheat. Some cause human and animal Basidomycota are one of the major groups of the fungi kingdom.
Fungi are eukaryotic organisms that digest their food externally and absorb the nutrient molecules into its cells. Unlike plants, they do not make their own food through photosynthesis and unlike animals they are not mobile and absorb nutrition externally rather than internally. Fungi may be single-celled or multicellular. Multicellular fungi are composed of networks of long hollow tubes called hyphae.
The hyphae often gather in dense networks known as mycelium. The mycelium is the vegetative part of a fungus, and consists of the mass branching, thread-like hyphae.
The mycelium grows through the medium on which the fungus feeds. Because most fungi are embedded in the medium in which they grow, most often soilthey are often not visible. Although fungi lack true organsthe mycelia can become organized into more complex reproductive structures fruiting bodies, or sporocarps, under the right conditions.
The sporocarp or fruiting body is a multicellular structure in which spore -producing structures, such as basidia or asci, are borne. The fruiting body is part of the sexual phase of a fungal life cyclethe rest of the life cycle is characterized by its vegetative mycelial growth. The sporocarp of a basidiomycete is known as a basidiocarpwhile the fruiting body of Basidiomycetes asexual reproduction definition ascomycete is known as an ascocarp. Mushroom is the common name given to the fruiting bodies of many fungal species.
Although these typically above-ground structures are the most conspicuous to humansthey make up only a small portion of the entire fungal body. The major divisions phyla of fungi are mainly classified based on their sexual reproductive structures. Currently, four or five main divisions are recognized, one of which is the Basidomycota or club fungi.
Another major division is the Ascomycota, or sac fungi. Together, the Basidomycota and Ascomycota are commonly known as "higher fungi" subkingdom Dikarya. Although considered monophyletic Swann and HibbertBasidiomycota is very varied, with unicellular and multicellular, sexual and asexual, and terrestrial and aquatic forms Swann and Hibbert As a result, "it is impossible to identify any morphological characteristics that are both unique to the group and constant in the group" Swann and Hibbert The production of basidia is the most diagnostic feature.
A basidium is a cell in which nuclear fusion and meiosis occur prior to developing the typically haploid basidiospores.
However, basidia are limited to the sexual Basidiomycota.
Another characteristic feature is a long-lived dikaryonin which all the cells in the thallus contain two haploid nuclei as a result of a mating event Swann and Hibbert Clamp connectionsa kind of hyphal outgrowth, are another unique feature to Basidiomycota Swann and Hibbert Basically, Basidiomycota are filamentous fungi composed of hyphae except for those forming yeastsand reproducing sexually via the formation of the specialized club-shaped end cells basidia that normally bear external spores usually fourwhich are the specialized meiospores known as basidiospores.
Asexually reproducing Basidiomycota discussed below can be recognized as members of this phylum by gross similarity to others, by the formation of the distinctive anatomical feature known as the clamp connection, by components of the cell walland definitively by phylogenetic molecular analysis of DNA sequence data.
The most recent classification Hibbett et al. As now classified, the subphyla join and also cut across various obsolete taxonomic groups see below previously commonly used to describe various Basidiomycota.
The Basidiomycota had traditionally been divided into two Basidiomycetes asexual reproduction definition classes, the Homobasidiomycetes including true mushrooms ; and the Heterobasidiomycetes the Jelly, Rust, and Smut fungi. Previously, the entire Basidiomycota were called Basidiomycetesan invalid class level name coined in as a counterpart to the Ascomyceteswhen neither of these taxa were recognized as phyla.
The terms basidiomycetes and ascomycetes are frequently used loosely to refer to Basidiomycota and Ascomycota. They are often abbreviated to "basidios" and "ascos" as mycological slang. The Agaricomycotina includes what had previously been called the Hymenomycetes an obsolete morphological based class of Basidiomycota that formed hymenial layers on their fruitbodiesthe Gasteromycetes another obsolete class that included species mostly lacking hymenia and mostly forming spores in enclosed fruitbodiesas well as most of the jelly fungi.
The Ustilaginomycotina are most but not all of the smut fungi, along with the Exobasidiales.
Unlike higher animals and plantswhich have readily recognizable male and female counterparts, Basidiomycota except for the Rust Pucciniales tend to have mutually indistinguishable, compatible haploidswhich
Basidiomycetes asexual reproduction definition usually mycelia being composed of filamentous hyphae. Typically, haploid Basidiomycota mycelia fuse via plasmogamy and then the compatible nuclei migrate into each other's mycelia and pair up with the resident nuclei.
Karyogamy is delayed, so that the compatible nuclei remain in pairs, called a dikaryon. The hyphae are then said to be dikaryotic. Conversely, the haploid mycelia are called monokaryons.
Often, the dikaryotic mycelium is more vigorous than the individual monokaryotic mycelia, and proceeds to take over the substrate in which they are growing. The dikaryons can be long-lived, lasting years, decades, or centuries.
The monokaryons are neither male nor female. They either a bipolar unifactorial or a tetrapolar bifactorial mating system. Basidiomycetes asexual reproduction definition results in the fact that following meiosisthe resulting haploid basidiospores and resultant monokaryons have nuclei that are compatible with 50 percent if bipolar or 25 percent if tetrapolar of their sister basidiospores and their resultant monokaryons because the mating genes must differ for them to be compatible.
However, there are many variations of these genes in the population, and therefore, over 90 percent of monokaryons are compatible with each other.
It is as if there were multiple sexes. The maintenance of the dikaryotic status in dikaryons in many Basidiomycota is facilitated by the formation of clamp connections that physically appear to help coordinate and re-establish pairs of compatible following synchronous mitotic nuclear divisions.
Variations "Basidiomycetes asexual reproduction definition" frequent and multiple. In a typical Basidiomycota lifecycle, the long lasting dikaryons periodically seasonally or occasionally produce basidia, the specialized usually club-shaped end cells, in which a pair of compatible nuclei fuse karyogamy to form a diploid cell. Meiosis follows shortly with the production of 4 haploid nuclei that migrate into four external, usually apical basidiospores.
Typically the basidiospores are ballistic, hence they are sometimes also called ballistospores. In most species, the basidiospores disperse and each can start a new haploid mycelium, continuing the life cycle. Basidia are microscopic, but they are often produced on or in multicelled large fructifications called basidiocarps or
Basidiomycetes asexual reproduction definition, or fruitbodiesvariously called mushroomspuffballs, and so forth.
Ballistic basidiospores are formed on sterigmatawhich are tapered spine-like projections on basidia, and are typically curved, like the horns of a bull. In some Basidiomycota, the spores are not ballistic, and the sterigmata may be straight, Basidiomycetes asexual reproduction definition to stubs, or absent.
The basidiospores of these non-ballistosporic basidia may either bud off, or be released via dissolution or disintegration of the basidia. In summary, meiosis takes place in a diploid basidium. Each one of the four haploid nuclei migrates into its own basidiospore.
The basidiospores are ballistically discharged and start new haploid mycelia called monokaryons.
There are no typical males or females, rather there are compatible thalli with multiple compatibility factors. Plasmogamy between compatible individuals leads to delayed karyogamy leading to establishment of a dikaryon. The dikaryon is long lasting but ultimately gives rise to either fruitbodies with basidia or directly to basidia without fruitbodies. The paired dikaryon in the basidium fuse i. The diploid basidium begins the cycle again.
There are many variations "Basidiomycetes asexual reproduction definition" the Basidiomycota life cycle from the typical cycle.
Some Basidiomycota are self compatible and spontaneously form dikaryons without a separate compatible thallus being involved. These fungi are said to be homothallic versus the normal heterothallic species with mating types. Others are secondarily homothallicin that two compatible nuclei following meiosis migrate into each basidiospore, which is then dispersed as a pre-existing dikaryon. Often such species form only two spores per basidium, but that too varies.
Following meiosis, mitotic divisions can occur in the basidium.
Multiple numbers of basidiospores can result, including odd numbers via degeneration of nuclei, or pairing up of nuclei, or lack of migration of nuclei.
For example, the chanterelle genus Craterellus often has 6-spored basidia, while some corticioid Sistotrema species can have 2- 4- 6- or 8-spored basidia, "Basidiomycetes asexual reproduction definition" the cultivated button mushroom, Agaricus bisporus can have 1- 2- 3- or 4-spored basidia under some circumstances. Occasionally monokaryons of some taxa can form morphologically fully formed basidiomes and anatomically correct basidia and ballistic basidiospores in the absence of dikaryon formation, diploid nuclei, and meiosis.