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24.3D: Basidiomycota: The Club Fungi - Biology


The basidiomycota are mushroom-producing fungi with developing, club-shaped fruiting bodies called basidia on the gills under its cap.

Learning Objectives

  • Describe the ecology and reproduction of the Basidiomycota

Key Points

  • The majority of edible fungi belong to the Phylum Basidiomycota.
  • The basidiomycota includes shelf fungus, toadstools, and smuts and rusts.
  • Unlike most fungi, basidiomycota reproduce sexually as opposed to asexually.
  • Two different mating strains are required for the fusion of genetic material in the basidium which is followed by meiosis producing haploid basidiospores.
  • Mycelia of different mating strains combine to produce a secondary mycelium that contains haploid basidiospores in what is called the dikaryotic stage, where the fungi remains until a basidiocarp (mushroom) is generated with the developing basidia on the gills under its cap.

Key Terms

  • basidiocarp: a fruiting body that protrudes from the ground, known as a mushroom, which has a developing basidia on the gills under its cap
  • basidiomycete: a fungus of the phylum Basidiomycota, which produces sexual spores on a basidium
  • Basidiomycota: a taxonomic division within the kingdom Fungi: 30,000 species of fungi that produce spores from a basidium
  • basidium: a small structure, shaped like a club, found in the Basidiomycota phylum of fungi, that bears four spores at the tips of small projections
  • basidiospore: a sexually-reproductive spore produced by fungi of the phylum Basidiomycota

Basidiomycota: The Club Fungi

The fungi in the Phylum Basidiomycota are easily recognizable under a light microscope by their club-shaped fruiting bodies called basidia (singular, basidium), which are the swollen terminal cell of a hypha. The basidia, which are the reproductive organs of these fungi, are often contained within the familiar mushroom, commonly seen in fields after rain, on the supermarket shelves, and growing on your lawn. These mushroom-producing basidiomyces are sometimes referred to as “gill fungi” because of the presence of gill-like structures on the underside of the cap. The “gills” are actually compacted hyphae on which the basidia are borne. This group also includes shelf fungus, which cling to the bark of trees like small shelves. In addition, the basidiomycota includes smuts and rusts, which are important plant pathogens, and toadstools. Most edible fungi belong to the Phylum Basidiomycota; however, some basidiomycetes produce deadly toxins. For example, Cryptococcus neoformans causes severe respiratory illness.

The lifecycle of basidiomycetes includes alternation of generations. Spores are generally produced through sexual reproduction, rather than asexual reproduction. The club-shaped basidium carries spores called basidiospores. In the basidium, nuclei of two different mating strains fuse (karyogamy), giving rise to a diploid zygote that then undergoes meiosis. The haploid nuclei migrate into basidiospores, which germinate and generate monokaryotic hyphae. The mycelium that results is called a primary mycelium. Mycelia of different mating strains can combine and produce a secondary mycelium that contains haploid nuclei of two different mating strains. This is the dikaryotic stage of the basidiomyces lifecyle and it is the dominant stage. Eventually, the secondary mycelium generates a basidiocarp, which is a fruiting body that protrudes from the ground; this is what we think of as a mushroom. The basidiocarp bears the developing basidia on the gills under its cap.


Enzymes from Basidiomycetes—Peculiar and Efficient Tools for Biotechnology

Rosane Marina Peralta , . Adelar Bracht , in Biotechnology of Microbial Enzymes , 2017

Abstract

Basidiomycetes are considered to be a very interesting group of fungi given their exceptional adjustment abilities to accommodate themselves to the detrimental conditions of the environment where they constantly act as natural lignocellulose destroyers. Basidiomycetes possess the two types of extracellular enzymatic systems necessary to degrade the vegetal biomass: (1) a hydrolytic system responsible for polysaccharide degradation, consisting mainly of xylanases and cellulases and (2) a unique oxidative ligninolytic system, which degrades lignin and opens phenyl rings this systemcomprises mainly laccases, ligninases, and peroxidases. Recent genomic studies of basidiomycetes have provided valuable information about the various ecological groups including white rot and brown rot fungi. The ability of basidiomycetes to degrade the complex structure of lignocellulose makes them potentially useful in the exploration of the lignocellulosic biomass for the production of fuel ethanol and other value-added commodity chemicals. No less important is their potential in biodegradation and bioremediation processes, thanks to the capability of their ligninolytic system in degrading a wide range of xenobiotic compounds. In this chapter, special attention is devoted to those enzymes typically produced by basidiomycetes with a high potential for biotechnological applications.


Economic Importance of Basidiomycetes | Club Fungi

Many of the Basidiomycetes are of great economic importance because of their beneficial as well as harmful nature. Some of them are the causative agents of most destructive diseases of our cereal crops.

To this category belong the smut diseases of com, wheat, oats, and barley as well as the wheat rusts. They destroy several million rupees worth of crops every year.

Some of the higher Basidiomycetes such as the pore fungi are the common wood rotters. They destroy lumbar and timber. Mushrooms which also belong to this group are of great economic value as food.

They are regularly cultivated for being delicious. The young fleshy sporophores of many species of puff balls (Lycoperdon and Clavatia) are also edible. Clavatia contains an anticancer substance calvacin.

The toad stools, however, are poisonous. Some of these such as Amanita are fatally poisonous whereas others cause only discomfort. Many members of this class form ectotrophic mycorrhizal associations with the roots of forest trees.

The association is mutually beneficial. The fungus obtains sugars and other organic substances from the roots of the tree partner whereas the mantle of the fungal partner serves to pass on nitrogen, phosphorus, and other elements absorbed by the mycelium to the root.

The saprophytic Basidiomycetes play a significant role in decomposing the dead fallen leaves and other forest litter converting waste material and returning it to the soil.

Two hypotheses have been put forth to explain the origin of the Basidiomycetes. They are the Ascomycetean hypothesis and Phycomycetean hypothesis. The consensus of opinion now favours the first view.

Ascomycetean Hypothesis:

According to this hypothesis, Basidiomycetes have evolved from Ascomycetes. This view is based on the fact that the Basidiomycetes resemble Ascomycetes more closely than any other class of fungi.

These resemblances are:

1. Their hyphal structure is similar.

2. In both the classes plasmogamy is not immediately followed by karyogamy. It is delayed for some time so that the resultant fusion cell contains two nuclei.

3. Secondary mycelium is homologous to the ascogenous hyphae of the Ascomycetes.

4. Clamp connections of the Basidiomycetes are homologous to the croziers of the Ascomycetes.

5. Asexual reproduction takes place by means of conidia which are produced in the same way in both the classes.

6. Basidia are homologous to the asci. Both have a similar origin and early development. In fact basidium is considered an early evolutionary development from an ascus of the Ascomycetes.

7. Basidiospores are homologous to the ascospores.

8. Basidiocarps are comparable to the ascocarps.

From the above-mentioned similarities mycologists conclude that the Basidiomycetes have arisen from the Ascomycetes. In fact they believe that a basidium is an evolutionary development from an ascus.

The fact that in some Ascomycetes the ascus produces only four ascospores gives further support to the close affinity between the two classes.

The views regarding evolution within the Basidiomycetes are rather speculative. Some mycologists think that the Basidiomycetes with septate basidia (phragmobasidia) are nearer to the ancestral Ascomycetes.

On this basis the Heterobasidiomycetidae such as rusts (Uredinales) are considered primitive. The rust spermagonium suggests a relationship to the Ascomycetes.

According to this view, the unseptate basidium (holobasidium) of the Homobasidiomycetidae is more advanced and derived from the septate basidium by simplification in which the septa disappeared.

The massive fructifications of the Homobasidiomycetidae support the view that they are more advanced than the Heterobasidiomycetidae.

Some mycologists, however, maintain that the Heterobasidiomycetidae are more advanced. They have arisen from the simpler members of the Homobasidiomycetidae much like the ancestors of Agaricus.

This viewpoint is supported by the fact that the unseptate basidium (holobasidium) is very much similar to the unseptate ascus. According to this interpretation, Homobasidiomycetidae are more primitive and closer to the ancestral Ascomycetes.


Zygomycota: The Conjugated Fungi

Zygomycetes have a thallus of coenocytic hyphae in which the nuclei are haploid when the organism is in the vegetative stage. The fungi usually reproduce asexually by producing sporangiospores (Figure). The black tips of bread mold are the swollen sporangia packed with black spores (Figure). When spores land on a suitable substrate, they germinate and produce a new mycelium. Sexual reproduction starts when conditions become unfavorable. Two opposing mating strains (type + and type –) must be in close proximity for gametangia from the hyphae to be produced and fuse, leading to karyogamy. The developing diploid zygospores have thick coats that protect them from desiccation and other hazards. They may remain dormant until environmental conditions are favorable. When the zygospore germinates, it undergoes meiosis and produces haploid spores, which will, in turn, grow into a new organism. This form of sexual reproduction in fungi is called conjugation (although it differs markedly from conjugation in bacteria and protists), giving rise to the name “conjugated fungi”.

Zygomycetes have asexual and asexual life cycles. In the sexual life cycle, plus and minus mating types conjugate to form a zygosporangium. Sporangia grow at the end of stalks, which appear as (a) white fuzz seen on this bread mold, Rhizopus stolonifer. The (b) tips of bread mold are the spore-containing sporangia. (credit b: modification of work by "polandeze"/Flickr)


Phylum Ascomycota: Life Cycle

Let's turn our attention to the life cycle of the typical ascomycete depicted in Figure 3. We will start with step 1 in the sexual part of the life cycle, in which two compatible haploid hyphae become intertwined and form an ascogonium and an antheridium (not to be confused with the male gametangium known as an antheridium in plants). In this case, in step 2, the ascogonium acts as a "female" and accepts nuclei from the antheridium after plasmogamy has occurred. In step 3, the resultant dikaryon is then capable of forming a cup-shaped ascocarp. In step 4, asci begin to form on the surface of the ascocarp at the tips of the dikaryotic mycelium, and in step 5, karyogamy occurs to form the highly transient diploid nucleus. In step 6, the diploid nucleus immediately undergoes meiosis, yielding four, genetically distinct, haploid nuclei. In step 7, after an additional round of mitosis, the ascus now contains eight haploid nuclei. In step 8, these eight nuclei will eventually develop into eight ascospores, which are released from the ascus on the surface of the ascocarp. In the final step in the sexual cycle (step 9), haploid mycelia arise from the aforementioned ascospores as the sexual cycle begins again.

Figure 3. An ascomycete life cycle. (Click image to enlarge)

Next, turn your attention to the left side of the diagram. Step 10 depicts the asexual part of the life cycle. Here, a compatible haploid partner is not present and the haploid mycelium is capable of producing asexual spores (conidia) by segmentation of its hyphae. These segments will compartmentalize into conidia, and wind or water dispersal will follow.


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Basidiomycota: The Club Fungi

The fungi in the Phylum Basidiomycota are easily recognizable under a light microscope by their club-shaped fruiting bodies called basidia (singular, basidium ), which are the swollen terminal cells of hyphae. The basidia, which are the reproductive organs of these fungi, are often contained within the familiar mushroom, commonly seen in fields after rain, on the supermarket shelves, and growing on your lawn (Figure). These mushroom-producing basidiomycetes are sometimes referred to as “gill fungi” because of the presence of gill-like structures on the underside of the cap. The gills are actually compacted hyphae on which the basidia are borne. This group also includes shelf fungi, which cling to the bark of trees like small shelves. In addition, the basidiomycota include smuts and rusts, which are important plant pathogens. Most edible fungi belong to the Phylum Basidiomycota however, some basidiomycota are inedible and produce deadly toxins. For example, Cryptococcus neoformans causes severe respiratory illness. The infamous death cap mushroom (Amanita phalloides) is related to the fly agaric seen at the beginning of the previous section.

Fairy ring. The fruiting bodies of a basidiomycete form a ring in a meadow, commonly called “fairy ring.” The best-known fairy ring fungus has the scientific name Marasmius oreades. The body of this fungus, its mycelium, is underground and grows outward in a circle. As it grows, the mycelium depletes the soil of nitrogen, causing the mycelia to grow away from the center and leading to the “fairy ring” of fruiting bodies where there is adequate soil nitrogen. (Credit: "Cropcircles"/Wikipedia Commons)]

The lifecycle of basidiomycetes includes alternation of generations (Figure). Most fungi are haploid through most of their life cycles, but the basidiomycetes produce both haploid and dikaryotic mycelia, with the dikaryotic phase being dominant. (Note: The dikaryotic phase is technically not diploid, since the nuclei remain unfused until shortly before spore production.) In the basidiomycetes, sexual spores are more common than asexual spores. The sexual spores form in the club-shaped basidium and are called basidiospores. In the basidium, nuclei of two different mating strains fuse (karyogamy), giving rise to a diploid zygote that then undergoes meiosis. The haploid nuclei migrate into four different chambers appended to the basidium, and then become basidiospores.

Each basidiospore germinates and generates monokaryotic haploid hyphae. The mycelium that results is called a primary mycelium. Mycelia of different mating strains can combine and produce a secondary mycelium that contains haploid nuclei of two different mating strains. This is the dominant dikaryotic stage of the basidiomycete life cycle. Thus, each cell in this mycelium has two haploid nuclei, which will not fuse until formation of the basidium. Eventually, the secondary mycelium generates a basidiocarp , a fruiting body that protrudes from the ground—this is what we think of as a mushroom. The basidiocarp bears the developing basidia on the gills under its cap.


Contents

A recent classification [4] adopted by a coalition of 67 mycologists recognizes three subphyla (Pucciniomycotina, Ustilaginomycotina, Agaricomycotina) and two other class level taxa (Wallemiomycetes, Entorrhizomycetes) outside of these, among the Basidiomycota. As now classified, the subphyla join and also cut across various obsolete taxonomic groups (see below) previously commonly used to describe Basidiomycota. According to a 2008 estimate, Basidiomycota comprise three subphyla (including six unassigned classes) 16 classes, 52 orders, 177 families, 1,589 genera, and 31,515 species. [5]

Traditionally, the Basidiomycota were divided into two classes, now obsolete:

Previously the entire Basidiomycota were called Basidiomycetes, an invalid class level name coined in 1959 as a counterpart to the Ascomycetes, when neither of these taxa were recognized as divisions. 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. [ citation needed ]

Agaricomycotina Edit

The Agaricomycotina include what had previously been called the Hymenomycetes (an obsolete morphological based class of Basidiomycota that formed hymenial layers on their fruitbodies), the Gasteromycetes (another obsolete class that included species mostly lacking hymenia and mostly forming spores in enclosed fruitbodies), as well as most of the jelly fungi. This sub-phyla also includes the "classic" mushrooms, polypores, corals, chanterelles, crusts, puffballs and stinkhorns. [6] The three classes in the Agaricomycotina are the Agaricomycetes, the Dacrymycetes, and the Tremellomycetes. [7]

The class Wallemiomycetes is not yet placed in a subdivision, but recent genomic evidence suggests that it is a sister group of Agaricomycotina. [8] [9]

Pucciniomycotina Edit

The Pucciniomycotina include the rust fungi, the insect parasitic/symbiotic genus Septobasidium, a former group of smut fungi (in the Microbotryomycetes, which includes mirror yeasts), and a mixture of odd, infrequently seen, or seldom recognized fungi, often parasitic on plants. The eight classes in the Pucciniomycotina are Agaricostilbomycetes, Atractiellomycetes, Classiculomycetes, Cryptomycocolacomycetes, Cystobasidiomycetes, Microbotryomycetes, Mixiomycetes, and Pucciniomycetes. [10]

Ustilaginomycotina Edit

The Ustilaginomycotina are most (but not all) of the former smut fungi and the Exobasidiales. The classes of the Ustilaginomycotina are the Exobasidiomycetes, the Entorrhizomycetes, and the Ustilaginomycetes. [11]

Genera included Edit

There are several genera classified in the Basidiomycota that are 1) poorly known, 2) have not been subjected to DNA analysis, or 3) if analysed phylogenetically do not group with as yet named or identified families, and have not been assigned to a specific family (i.e., they are incertae sedis with respect to familial placement). These include:

  • AnastomycesW.P.Wu, B.Sutton & Gange (1997)
  • AnguillomycesMarvanová & Bärl. (2000)
  • AnthoseptobasidiumRick (1943)
  • ArcisporaMarvanová & Bärl. (1998)
  • ArrasiaBernicchia, Gorjón & Nakasone (2011)
  • BrevicellopsisHjortstam & Ryvarden (2008)
  • CelatogloeaP.Roberts (2005)
  • CleistocybeAmmirati, A.D.Parker & Matheny (2007)
  • CystogloeaP. Roberts (2006)
  • DacryomycetopsisRick (1958)
  • EriocybeVellinga (2011)
  • HallenbergiaDhingra & Priyanka (2011)
  • HymenoporusTkalčec, Mešić & Chun Y.Deng (2015)
  • KryptastrinaOberw. (1990)
  • MicrostellaK.Ando & Tubaki (1984)
  • NeotyphulaWakef. (1934)
  • NodulosporaMarvanová & Bärl. (2000)
  • ParaphelariaCorner (1966)
  • PunctulariopsisGhob.-Nejh. (2010)
  • RadulodontiaHjortstam & Ryvarden (2008)
  • RestilagoVánky (2008)
  • SinofavusW.Y.Zhuang (2008)
  • ZanchiaRick (1958)
  • ZygodesmusCorda (1837)
  • ZygogloeaP.Roberts (1994)

Unlike animals and plants which have readily recognizable male and female counterparts, Basidiomycota (except for the Rust (Pucciniales)) tend to have mutually indistinguishable, compatible haploids which are 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 have either a bipolar (unifactorial) or a tetrapolar (bifactorial) mating system. This results in the fact that following meiosis, the resulting haploid basidiospores and resultant monokaryons, have nuclei that are compatible with 50% (if bipolar) or 25% (if tetrapolar) of their sister basidiospores (and their resultant monokaryons) because the mating genes must differ for them to be compatible. However, there are sometimes more than two possible alleles for a given locus, and in such species, depending on the specifics, over 90% of monokaryons could be compatible with each other.

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 nuclei following synchronous mitotic nuclear divisions. Variations are 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 4 external, usually apical basidiospores. Variations occur, however. 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 lifecycle. Basidia are microscopic but they are often produced on or in multicelled large fructifications called basidiocarps or basidiomes, or fruitbodies), variously called mushrooms, puffballs, etc. Ballistic basidiospores are formed on sterigmata which 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, reduced to stubbs, 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 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.e. karyogamy takes place). The diploid basidium begins the cycle again.

Meiosis Edit

Coprinopsis cinerea is a basidiomycete mushroom. It is particularly suited to the study of meiosis because meiosis progresses synchronously in about 10 million cells within the mushroom cap, and the meiotic prophase stage is prolonged. Burns et al. [12] studied the expression of genes involved in the 15-hour meiotic process, and found that the pattern of gene expression of C. cinerea was similar to two other fungal species, the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. These similarities in the patterns of expression led to the conclusion that the core expression program of meiosis has been conserved in these fungi for over half a billion years of evolution since these species diverged. [12]

Cryptococcus neoformans and Ustilago maydis are examples of pathogenic basidiomycota. Such pathogens must be able to overcome the oxidative defenses of their respective hosts in order to produce a successful infection. The ability to undergo meiosis may provide a survival benefit for these fungi by promoting successful infection. A characteristic central feature of meiosis is recombination between homologous chromosomes. This process is associated with repair of DNA damage, particularly double-strand breaks. The ability of C. neoformans and U. maydis to undergo meiosis may contribute to their virulence by repairing the oxidative DNA damage caused by their host's release of reactive oxygen species. [13] [14]

Many variations occur. Some 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 homothallic, in 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 six-spored basidia, while some corticioid Sistotrema species can have two-, four-, six-, or eight-spored basidia, and the cultivated button mushroom, Agaricus bisporus. can have one-, two-, three- or four-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. A rare few number of taxa have extended diploid lifecycles, but can be common species. Examples exist in the mushroom genera Armillaria and Xerula, both in the Physalacriaceae. Occasionally, basidiospores are not formed and parts of the "basidia" act as the dispersal agents, e.g. the peculiar mycoparasitic jelly fungus, Tetragoniomyces or the entire "basidium" acts as a "spore", e.g. in some false puffballs (Scleroderma). In the human pathogenic genus Cryptococcus, four nuclei following meiosis remain in the basidium, but continually divide mitotically, each nucleus migrating into synchronously forming nonballistic basidiospores that are then pushed upwards by another set forming below them, resulting in four parallel chains of dry "basidiospores".

Other variations occur, some as standard lifecycles (that themselves have variations within variations) within specific orders.

Rusts Edit

Rusts (Pucciniales, previously known as Uredinales) at their greatest complexity, produce five different types of spores on two different host plants in two unrelated host families. Such rusts are heteroecious (requiring two hosts) and macrocyclic (producing all five spores types). Wheat stem rust is an example. By convention, the stages and spore states are numbered by Roman numerals. Typically, basidiospores infect host one, also known as the alternate or sexual host, and the mycelium forms pycnidia, which are miniature, flask-shaped, hollow, submicroscopic bodies embedded in the host tissue (such as a leaf). This stage, numbered "0", produces single-celled spores that ooze out in a sweet liquid and that act as nonmotile spermatia, and also protruding receptive hyphae. Insects and probably other vectors such as rain carry the spermatia from spermagonium to spermagonium, cross inoculating the mating types. Neither thallus is male or female. Once crossed, the dikaryons are established and a second spore stage is formed, numbered "I" and called aecia, which form dikaryotic aeciospores in dry chains in inverted cup-shaped bodies embedded in host tissue. These aeciospores then infect the second host, known as the primary or asexual host (in macrocyclic rusts). On the primary host a repeating spore stage is formed, numbered "II", the urediospores in dry pustules called uredinia. Urediospores are dikaryotic and can infect the same host that produced them. They repeatedly infect this host over the growing season. At the end of the season, a fourth spore type, the teliospore, is formed. It is thicker-walled and serves to overwinter or to survive other harsh conditions. It does not continue the infection process, rather it remains dormant for a period and then germinates to form basidia (stage "IV"), sometimes called a promycelium. In the Pucciniales, the basidia are cylindrical and become 3-septate after meiosis, with each of the 4 cells bearing one basidiospore each. The basidiospores disperse and start the infection process on host 1 again. Autoecious rusts complete their life-cycles on one host instead of two, and microcyclic rusts cut out one or more stages.

Smuts Edit

The characteristic part of the life-cycle of smuts is the thick-walled, often darkly pigmented, ornate, teliospore that serves to survive harsh conditions such as overwintering and also serves to help disperse the fungus as dry diaspores. The teliospores are initially dikaryotic but become diploid via karyogamy. Meiosis takes place at the time of germination. A promycelium is formed that consists of a short hypha (equated to a basidium). In some smuts such as Ustilago maydis the nuclei migrate into the promycelium that becomes septate (i.e., divided into cellular compartments separated by cell walls called septa), and haploid yeast-like conidia/basidiospores sometimes called sporidia, bud off laterally from each cell. In various smuts, the yeast phase may proliferate, or they may fuse, or they may infect plant tissue and become hyphal. In other smuts, such as Tilletia caries, the elongated haploid basidiospores form apically, often in compatible pairs that fuse centrally resulting in "H"-shaped diaspores which are by then dikaryotic. Dikaryotic conidia may then form. Eventually the host is infected by infectious hyphae. Teliospores form in host tissue. Many variations on these general themes occur.

Smuts with both a yeast phase and an infectious hyphal state are examples of dimorphic Basidiomycota. In plant parasitic taxa, the saprotrophic phase is normally the yeast while the infectious stage is hyphal. However, there are examples of animal and human parasites where the species are dimorphic but it is the yeast-like state that is infectious. The genus Filobasidiella forms basidia on hyphae but the main infectious stage is more commonly known by the anamorphic yeast name Cryptococcus, e.g. Cryptococcus neoformans and Cryptococcus gattii.

The dimorphic Basidiomycota with yeast stages and the pleiomorphic rusts are examples of fungi with anamorphs, which are the asexual stages. Some Basidiomycota are only known as anamorphs. Many are yeasts, collectively called basidiomycetous yeasts to differentiate them from ascomycetous yeasts in the Ascomycota. Aside from yeast anamorphs, and uredinia, aecia and pycnidia, some Basidiomycota form other distinctive anamorphs as parts of their life-cycles. Examples are Collybia tuberosa [15] with its apple-seed-shaped and coloured sclerotium, Dendrocollybia racemosa [16] with its sclerotium and its Tilachlidiopsis racemosa conidia, Armillaria with their rhizomorphs, [17] Hohenbuehelia [18] with their Nematoctonus nematode infectious, state [19] and the coffee leaf parasite, Mycena citricolor [17] and its Decapitatus flavidus propagules called gemmae.


What is the scientific name for club fungi?

Click to read full detail here. In this regard, what is the common name for club fungi?

Secondly, why Basidiomycetes are called club fungi? Basidiomycetes are often called club fungi because the cells (basidia) that bear the sexual spores resemble a small club. Biologically, basidiomycetes follow the same theme as the rest of the fungal kingdom they are important decomposers, plant pathogens, and symbionts with plants (mycorrhizal).

Then, what is the scientific name of basidiomycota?

Basidiomycota
Basidiomycetes from Ernst Haeckel's 1904 Kunstformen der Natur
Scientific classification
Kingdom: Fungi
Subkingdom: Dikarya

What is meant by club fungi?

Definition of club fungus. : any of various basidiomycetes (family Clavariaceae) with a simple or branched often club-shaped sporophore.


Asexual Ascomycota and Basidiomycota

Imperfect fungi—those that do not display a sexual phase—use to be classified in the form phylum Deuteromycota, , a classification group no longer used in the present, ever-developing classification of organisms. While Deuteromycota use to be a classification group, recent moleclular analysis has shown that the members classified in this group belong to the Ascomycota or the Basidiomycota classifications. Since they do not possess the sexual structures that are used to classify other fungi, they are less well described in comparison to other members. Most members live on land, with a few aquatic exceptions. They form visible mycelia with a fuzzy appearance and are commonly known as mold.

Reproduction of the fungi in this group is strictly asexual and occurs mostly by production of asexual conidiospores (see the figure below). Some hyphae may recombine and form heterokaryotic hyphae. Genetic recombination is known to take place between the different nuclei.

Aspergillus niger is an asexually reproducing fungus (phylum Ascomycota) commonly found as a food contaminant. The spherical structure in this light micrograph is a conidiophore. (credit: modification of work by Dr. Lucille Georg, CDC scale-bar data from Matt Russell)

The fungi in this group have a large impact on everyday human life. The food industry relies on them for ripening some cheeses. The blue veins in Roquefort cheese and the white crust on Camembert are the result of fungal growth. The antibiotic penicillin was originally discovered on an overgrown Petri plate, on which a colony of Penicillium fungi killed the bacterial growth surrounding it. Other fungi in this group cause serious diseases, either directly as parasites (which infect both plants and humans), or as producers of potent toxic compounds, as seen in the aflatoxins released by fungi of the genus Aspergillus.