A characteristic that places fungi in a different kingdom from
bacteria, and some
chitin in their
cell walls. Fungi, like animals, are
heterotrophs; they acquire their food by absorbing dissolved molecules, typically by secreting
digestive enzymes into their environment. Fungi do not
photosynthesize. Growth is their means of
mobility, except for
spores (a few of which are
flagellated), which may travel through the air or water. Fungi are the principal
decomposers in ecological systems. These and other differences place fungi in a single group of related organisms, named the Eumycota (true fungi or Eumycetes), that share a
common ancestor (i.e. they form a monophyletic group), an interpretation that is also strongly supported by
molecular phylogenetics. This fungal group is distinct from the structurally similar
myxomycetes (slime molds) and
oomycetes (water molds). The discipline of
biology devoted to the study of fungi is known as
mycology (from the
Greekμύκηςmykes, mushroom). In the past mycology was regarded as a branch of
botany, although it is now known that fungi are genetically more closely related to animals than to plants.
The fungus kingdom encompasses an enormous diversity of
taxa with varied ecologies,
life cycle strategies, and
morphologies ranging from unicellular aquatic
chytrids to large mushrooms. However, little is known of the true
biodiversity of the fungus kingdom, which has been estimated at 2.2 million to 3.8 million species. Of these, only about 148,000 have been described, with over 8,000 species known to be detrimental to plants and at least 300 that can be pathogenic to humans. Ever since the pioneering 18th and 19th century
taxonomical works of
Christiaan Hendrik Persoon, and
Elias Magnus Fries, fungi have been classified according to their morphology (e.g., characteristics such as spore color or microscopic features) or
physiology. Advances in
molecular genetics have opened the way for
DNA analysis to be incorporated into taxonomy, which has sometimes challenged the historical groupings based on morphology and other traits.
Phylogenetic studies published in the first decade of the 21st century have helped reshape the classification within the fungi kingdom, which is divided into one
phyla, and ten
The English word fungus is directly adopted from the
Latinfungus (mushroom), used in the writings of
Pliny. This in turn is derived from the
Greek word sphongos (σφόγγος 'sponge'), which refers to the
macroscopic structures and morphology of mushrooms and molds; the
root is also used in other languages, such as the German Schwamm ('sponge') and Schimmel ('mold').
The word mycology is derived from the Greek mykes (μύκης 'mushroom') and logos (λόγος 'discourse'). It denotes the scientific study of fungi. The Latin adjectival form of "mycology" (mycologicæ) appeared as early as 1796 in a book on the subject by
Christiaan Hendrik Persoon. The word appeared in English as early as 1824 in a book by
Robert Kaye Greville. In 1836 the English naturalist
Miles Joseph Berkeley's publication The English Flora of Sir James Edward Smith, Vol. 5. also refers to mycology as the study of fungi.
Before the introduction of
molecular methods for phylogenetic analysis,
taxonomists considered fungi to be members of the
plant kingdom because of similarities in lifestyle: both fungi and plants are mainly
immobile, and have similarities in general morphology and growth habitat. Although inaccurate, the common misconception that fungi are plants persists among the general public due to their historical classification, as well as several similarities. Like plants, fungi often grow in soil and, in the case of
mushrooms, form conspicuous
fruit bodies, which sometimes resemble plants such as
mosses. The fungi are now considered a separate kingdom, distinct from both plants and animals, from which they appear to have
diverged around one billion years ago (around the start of the
Neoproterozoic Era). Some morphological, biochemical, and genetic features are shared with other organisms, while others are unique to the fungi, clearly separating them from the other kingdoms:
With plants: Fungi have a cell wall and
vacuoles. They reproduce by both sexual and asexual means, and like
basal plant groups (such as
spores. Similar to mosses and algae, fungi typically have
The cells of most fungi grow as tubular, elongated, and thread-like (filamentous) structures called
hyphae, which may contain multiple nuclei and extend by growing at their tips. Each tip contains a set of aggregated
vesicles—cellular structures consisting of
lipids, and other organic molecules—called the
Spitzenkörper. Both fungi and
oomycetes grow as filamentous hyphal cells. In contrast, similar-looking organisms, such as filamentous
green algae, grow by repeated cell division within a chain of cells. There are also single-celled fungi (
yeasts) that do not form hyphae, and some fungi have both hyphal and yeast forms.
Some species grow as unicellular yeasts that reproduce by
Dimorphic fungi can switch between a yeast phase and a hyphal phase in response to environmental conditions.
The fungal cell wall is made of a
chitin-glucan complex; while glucans are also found in plants and chitin in the
arthropods, fungi are the only organisms that combine these two structural molecules in their cell wall. Unlike those of plants and oomycetes, fungal cell walls do not contain cellulose.
As of 2020,[update] around 148,000 species of fungi have been
taxonomists, but the global biodiversity of the fungus kingdom is not fully understood. A 2017 estimate suggests there may be between 2.2 and 3.8 million species. The number of new fungi species discovered yearly has increased from 1,000 to 1,500 per year about 10 years ago, to about 2000 with a peak of more than 2,500 species in 2016. In the year 2019, 1882 new species of fungi were described, and it was estimated that more than 90% of fungi remain unknown. The following year, 2905 new species were described—the highest annual record of new fungus names. In mycology, species have historically been distinguished by a variety of methods and concepts. Classification based on
morphological characteristics, such as the size and shape of spores or fruiting structures, has traditionally dominated fungal taxonomy. Species may also be distinguished by their
physiological characteristics, such as their ability to metabolize certain biochemicals, or their reaction to
chemical tests. The
biological species concept discriminates species based on their ability to
mate. The application of
molecular tools, such as
DNA sequencing and phylogenetic analysis, to study diversity has greatly enhanced the resolution and added robustness to estimates of
genetic diversity within various taxonomic groups.
Mycology is the branch of
biology concerned with the systematic study of fungi, including their genetic and biochemical properties, their taxonomy, and their use to humans as a source of medicine, food, and
psychotropic substances consumed for religious purposes, as well as their dangers, such as poisoning or infection. The field of
phytopathology, the study of plant diseases, is closely related because many plant pathogens are fungi.
The use of fungi by humans dates back to prehistory;
Ötzi the Iceman, a well-preserved mummy of a 5,300-year-old
Neolithic man found frozen in the Austrian Alps, carried two species of
polypore mushrooms that may have been used as
tinder (Fomes fomentarius), or for medicinal purposes (Piptoporus betulinus). Ancient peoples have used fungi as food sources—often unknowingly—for millennia, in the preparation of leavened bread and fermented juices. Some of the oldest written records contain references to the destruction of crops that were probably caused by pathogenic fungi.
Most fungi grow as
hyphae, which are cylindrical, thread-like structures 2–10µm in diameter and up to several centimeters in length. Hyphae grow at their tips (apices); new hyphae are typically formed by emergence of new tips along existing hyphae by a process called branching, or occasionally growing hyphal tips fork, giving rise to two parallel-growing hyphae. Hyphae also sometimes fuse when they come into contact, a process called hyphal fusion (or
anastomosis). These growth processes lead to the development of a
mycelium, an interconnected network of hyphae. Hyphae can be either
coenocytic. Septate hyphae are divided into compartments separated by cross walls (internal cell walls, called septa, that are formed at
right angles to the cell wall giving the hypha its shape), with each compartment containing one or more nuclei; coenocytic hyphae are not compartmentalized. Septa have
pores that allow
organelles, and sometimes nuclei to pass through; an example is the
dolipore septum in fungi of the phylum Basidiomycota. Coenocytic hyphae are in essence
Many species have developed specialized hyphal structures for nutrient uptake from living hosts; examples include
haustoria in plant-parasitic species of most fungal phyla, and
arbuscules of several
mycorrhizal fungi, which penetrate into the host cells to consume nutrients.
Although fungi are
opisthokonts—a grouping of evolutionarily related organisms broadly characterized by a single posterior
flagellum—all phyla except for the
chytrids have lost their posterior flagella. Fungi are unusual among the eukaryotes in having a cell wall that, in addition to
β-1,3-glucan) and other typical components, also contains the
Fungal mycelia can become visible to the naked eye, for example, on various surfaces and
substrates, such as damp walls and spoiled food, where they are commonly called
molds. Mycelia grown on solid
agar media in laboratory
petri dishes are usually referred to as
colonies. These colonies can exhibit growth shapes and colors (due to spores or
pigmentation) that can be used as diagnostic features in the identification of species or groups. Some individual fungal colonies can reach extraordinary dimensions and ages as in the case of a
clonal colony of Armillaria solidipes, which extends over an area of more than 900ha (3.5 square miles), with an estimated age of nearly 9,000years.
apothecium—a specialized structure important in
sexual reproduction in the ascomycetes—is a cup-shaped fruit body that is often macroscopic and holds the
hymenium, a layer of tissue containing the spore-bearing cells. The fruit bodies of the basidiomycetes (
basidiocarps) and some ascomycetes can sometimes grow very large, and many are well known as
The mechanical pressure exerted by the appressorium is generated from physiological processes that increase intracellular
turgor by producing
osmolytes such as
glycerol. Adaptations such as these are complemented by
hydrolytic enzymes secreted into the environment to digest large organic molecules—such as
lipids—into smaller molecules that may then be absorbed as nutrients. The vast majority of filamentous fungi grow in a polar fashion (extending in one direction) by elongation at the tip (apex) of the hypha. Other forms of fungal growth include intercalary extension (longitudinal expansion of hyphal compartments that are below the apex) as in the case of some
endophytic fungi, or growth by volume expansion during the development of mushroom
stipes and other large organs. Growth of fungi as
multicellular structures consisting of
somatic and reproductive cells—a feature independently evolved in animals and plants—has several functions, including the development of fruit bodies for dissemination of sexual spores (see above) and
biofilms for substrate colonization and
Fungal reproduction is complex, reflecting the differences in lifestyles and genetic makeup within this diverse kingdom of organisms. It is estimated that a third of all fungi reproduce using more than one method of propagation; for example, reproduction may occur in two well-differentiated stages within the
life cycle of a species, the
teleomorph (sexual reproduction) and the
anamorph (asexual reproduction). Environmental conditions trigger genetically determined developmental states that lead to the creation of specialized structures for sexual or asexual reproduction. These structures aid reproduction by efficiently dispersing spores or spore-containing
Asexual reproduction occurs via vegetative spores (
conidia) or through
mycelial fragmentation. Mycelial fragmentation occurs when a fungal mycelium separates into pieces, and each component grows into a separate mycelium. Mycelial fragmentation and vegetative spores maintain
clonal populations adapted to a specific
niche, and allow more rapid dispersal than sexual reproduction. The "Fungi imperfecti" (fungi lacking the perfect or sexual stage) or
Deuteromycota comprise all the species that lack an observable sexual cycle. Deuteromycota (alternatively known as Deuteromycetes, conidial fungi, or mitosporic fungi) is not an accepted taxonomic clade and is now taken to mean simply fungi that lack a known sexual stage.
Sexual reproduction with
meiosis has been directly observed in all fungal phyla except
Glomeromycota (genetic analysis suggests meiosis in Glomeromycota as well). It differs in many aspects from sexual reproduction in animals or plants. Differences also exist between fungal groups and can be used to discriminate species by morphological differences in sexual structures and reproductive strategies. Mating experiments between fungal isolates may identify species on the basis of biological species concepts. The major fungal groupings have initially been delineated based on the morphology of their sexual structures and spores; for example, the spore-containing structures,
basidia, can be used in the identification of ascomycetes and basidiomycetes, respectively. Fungi employ two
heterothallic species allow mating only between individuals of the opposite
mating type, whereas
homothallic species can mate, and sexually reproduce, with any other individual or itself.
Most fungi have both a
haploid and a
diploid stage in their life cycles. In sexually reproducing fungi, compatible individuals may combine by fusing their hyphae together into an interconnected network; this process,
anastomosis, is required for the initiation of the sexual cycle. Many ascomycetes and basidiomycetes go through a
dikaryotic stage, in which the nuclei inherited from the two parents do not combine immediately after cell fusion, but remain separate in the hyphal cells (see
In ascomycetes, dikaryotic hyphae of the
hymenium (the spore-bearing tissue layer) form a characteristic hook (crozier) at the hyphal septum. During
cell division, the formation of the hook ensures proper distribution of the newly divided nuclei into the apical and basal hyphal compartments. An ascus (plural asci) is then formed, in which
karyogamy (nuclear fusion) occurs. Asci are embedded in an
ascocarp, or fruiting body. Karyogamy in the asci is followed immediately by meiosis and the production of
ascospores. After dispersal, the ascospores may germinate and form a new haploid mycelium.
Sexual reproduction in basidiomycetes is similar to that of the ascomycetes. Compatible haploid hyphae fuse to produce a dikaryotic mycelium. However, the dikaryotic phase is more extensive in the basidiomycetes, often also present in the vegetatively growing mycelium. A specialized anatomical structure, called a
clamp connection, is formed at each hyphal septum. As with the structurally similar hook in the ascomycetes, the clamp connection in the basidiomycetes is required for controlled transfer of nuclei during cell division, to maintain the dikaryotic stage with two genetically different nuclei in each hyphal compartment. A
basidiocarp is formed in which club-like structures known as
basidia generate haploid
basidiospores after karyogamy and meiosis. The most commonly known basidiocarps are mushrooms, but they may also take other forms (see
In fungi formerly classified as
Zygomycota, haploid hyphae of two individuals fuse, forming a
gametangium, a specialized cell structure that becomes a fertile
gamete-producing cell. The gametangium develops into a
zygospore, a thick-walled spore formed by the union of gametes. When the zygospore germinates, it undergoes
meiosis, generating new haploid hyphae, which may then form asexual
sporangiospores. These sporangiospores allow the fungus to rapidly disperse and germinate into new genetically identical haploid fungal mycelia.
The spores of most of the researched species of fungi are transported by wind. Such species often produce dry or
hydrophobic spores that do not absorb water and are readily scattered by raindrops, for example. In other species, both asexual and sexual spores or sporangiospores are often actively dispersed by forcible ejection from their reproductive structures. This ejection ensures exit of the spores from the reproductive structures as well as traveling through the air over long distances.
Specialized mechanical and physiological mechanisms, as well as spore surface structures (such as
hydrophobins), enable efficient spore ejection. For example, the structure of the
spore-bearing cells in some ascomycete species is such that the buildup of
substances affecting cell volume and fluid balance enables the explosive discharge of spores into the air. The forcible discharge of single spores termed ballistospores involves formation of a small drop of water (Buller's drop), which upon contact with the spore leads to its projectile release with an initial acceleration of more than 10,000g; the net result is that the spore is ejected 0.01–0.02cm, sufficient distance for it to fall through the
pores into the air below. Other fungi, like the
puffballs, rely on alternative mechanisms for spore release, such as external mechanical forces. The
hydnoid fungi (tooth fungi) produce spores on pendant, tooth-like or spine-like projections. The
bird's nest fungi use the force of falling water drops to liberate the spores from cup-shaped fruiting bodies. Another strategy is seen in the
stinkhorns, a group of fungi with lively colors and putrid odor that attract insects to disperse their spores.
Besides regular sexual reproduction with meiosis, certain fungi, such as those in the genera Penicillium and Aspergillus, may exchange genetic material via
parasexual processes, initiated by anastomosis between hyphae and
plasmogamy of fungal cells. The frequency and relative importance of parasexual events is unclear and may be lower than other sexual processes. It is known to play a role in intraspecific hybridization and is likely required for hybridization between species, which has been associated with major events in fungal evolution.
In contrast to
animals, the early fossil record of the fungi is meager. Factors that likely contribute to the under-representation of fungal species among fossils include the nature of fungal
fruiting bodies, which are soft, fleshy, and easily degradable tissues and the microscopic dimensions of most fungal structures, which therefore are not readily evident. Fungal fossils are difficult to distinguish from those of other microbes, and are most easily identified when they resemble
extant fungi. Often recovered from a
permineralized plant or animal host, these samples are typically studied by making thin-section preparations that can be examined with
light microscopy or
transmission electron microscopy. Researchers study
compression fossils by dissolving the surrounding matrix with acid and then using light or
scanning electron microscopy to examine surface details.
The earliest fossils possessing features typical of fungi date to the
Paleoproterozoic era, some 2,400 million years ago (
Ma); these multicellular
benthic organisms had filamentous structures capable of
anastomosis. Other studies (2009) estimate the arrival of fungal organisms at about 760–1060Ma on the basis of comparisons of the rate of evolution in closely related groups. The oldest fossilizied mycelium to be identified from its molecular composition is between 715 and 810 million years old. For much of the
Paleozoic Era (542–251Ma), the fungi appear to have been aquatic and consisted of organisms similar to the extant
chytrids in having flagellum-bearing spores. The evolutionary adaptation from an aquatic to a terrestrial lifestyle necessitated a diversification of ecological strategies for obtaining nutrients, including
saprobism, and the development of
mutualistic relationships such as
mycorrhiza and lichenization. Studies suggest that the ancestral ecological state of the
Ascomycota was saprobism, and that independent
lichenization events have occurred multiple times.
Lichens formed a component of the early terrestrial ecosystems, and the estimated age of the oldest terrestrial lichen fossil is 415Ma; this date roughly corresponds to the age of the oldest known
sporocarp fossil, a Paleopyrenomycites species found in the Rhynie Chert. The oldest fossil with microscopic features resembling modern-day basidiomycetes is Palaeoancistrus, found permineralized with a
fern from the Pennsylvanian. Rare in the fossil record are the Homobasidiomycetes (a
taxon roughly equivalent to the mushroom-producing species of the
amber-preserved specimens provide evidence that the earliest known mushroom-forming fungi (the extinct species Archaeomarasmius leggetti) appeared during the late
Some time after the
Permian–Triassic extinction event (251.4Ma), a fungal spike (originally thought to be an extraordinary abundance of fungal spores in
sediments) formed, suggesting that fungi were the dominant life form at this time, representing nearly 100% of the available
fossil record for this period. However, the relative proportion of fungal spores relative to spores formed by
algal species is difficult to assess, the spike did not appear worldwide, and in many places it did not fall on the Permian–Triassic boundary.
Sixty-five million years ago, immediately after the
Cretaceous–Paleogene extinction event that famously killed off most dinosaurs, there was a dramatic increase in evidence of fungi; apparently the death of most plant and animal species led to a huge fungal bloom like "a massive compost heap".
Although commonly included in botany curricula and textbooks, fungi are more closely related to
animals than to plants and are placed with the animals in the
monophyletic group of
opisthokonts. Analyses using
molecular phylogenetics support a
monophyletic origin of fungi. The
taxonomy of fungi is in a state of constant flux, especially due to research based on DNA comparisons. These current phylogenetic analyses often overturn classifications based on older and sometimes less discriminative methods based on morphological features and biological species concepts obtained from experimental
There is no unique generally accepted system at the higher taxonomic levels and there are frequent name changes at every level, from species upwards. Efforts among researchers are now underway to establish and encourage usage of a unified and more consistent
nomenclature. Until relatively recent (2012) changes to the
International Code of Nomenclature for algae, fungi and plants, fungal species could also have multiple scientific names depending on their life cycle and mode (sexual or asexual) of reproduction. Web sites such as
Index Fungorum and
MycoBank are officially recognized
nomenclatural repositories and list current names of fungal species (with cross-references to older
The 2007 classification of Kingdom Fungi is the result of a large-scale collaborative research effort involving dozens of mycologists and other scientists working on fungal taxonomy. It recognizes seven
phyla, two of which—the Ascomycota and the Basidiomycota—are contained within a branch representing
subkingdomDikarya, the most species rich and familiar group, including all the mushrooms, most food-spoilage molds, most plant pathogenic fungi, and the beer, wine, and bread yeasts. The accompanying
cladogram depicts the major fungal
taxa and their relationship to opisthokont and unikont organisms, based on the work of Philippe Silar, "The Mycota: A Comprehensive Treatise on Fungi as Experimental Systems for Basic and Applied Research" and Tedersoo et al. 2018. The lengths of the branches are not proportional to
phyla (sometimes called divisions) of fungi have been classified mainly on the basis of characteristics of their sexual
reproductive structures. As of 2019[update], nine major
lineages have been identified: Opisthosporidia, Chytridiomycota, Neocallimastigomycota, Blastocladiomycota, Zoopagomycota, Mucoromycota, Glomeromycota, Ascomycota and Basidiomycota.
Phylogenetic analysis has demonstrated that the
Microsporidia, unicellular parasites of animals and protists, are fairly recent and highly derived
endobiotic fungi (living within the tissue of another species). Previously considered to be "primitive" protozoa, they are now thought to be either a
basal branch of the Fungi, or a
sister group–each other's closest evolutionary relative.
Blastocladiomycota were previously considered a taxonomic clade within the Chytridiomycota. Molecular data and
ultrastructural characteristics, however, place the Blastocladiomycota as a sister clade to the Zygomycota, Glomeromycota, and Dikarya (Ascomycota and Basidiomycota). The blastocladiomycetes are
saprotrophs, feeding on decomposing organic matter, and they are parasites of all eukaryotic groups. Unlike their close relatives, the chytrids, most of which exhibit
zygotic meiosis, the blastocladiomycetes undergo
Neocallimastigomycota were earlier placed in the phylum Chytridiomycota. Members of this small phylum are
anaerobic organisms, living in the digestive system of larger herbivorous mammals and in other terrestrial and aquatic environments enriched in cellulose (e.g., domestic waste landfill sites). They lack
mitochondria but contain
hydrogenosomes of mitochondrial origin. As in the related chrytrids, neocallimastigomycetes form zoospores that are posteriorly uniflagellate or polyflagellate.
Ascomycota, commonly known as sac fungi or ascomycetes, constitute the largest taxonomic group within the Eumycota. These fungi form meiotic spores called
ascospores, which are enclosed in a special sac-like structure called an
ascus. This phylum includes
morels, a few
yeasts (e.g., of the genera Saccharomyces, Kluyveromyces, Pichia, and Candida), and many filamentous fungi living as saprotrophs, parasites, and mutualistic symbionts (e.g. lichens). Prominent and important genera of filamentous ascomycetes include Aspergillus, Penicillium, Fusarium, and Claviceps. Many ascomycete species have only been observed undergoing asexual reproduction (called
anamorphic species), but analysis of molecular data has often been able to identify their closest
teleomorphs in the Ascomycota. Because the products of meiosis are retained within the sac-like ascus, ascomycetes have been used for elucidating principles of genetics and heredity (e.g., Neurospora crassa).
Unlike true fungi, the
cell walls of oomycetes contain
cellulose and lack
chitin. Hyphochytrids have both chitin and cellulose. Slime molds lack a cell wall during the assimilative phase (except labyrinthulids, which have a wall of scales), and take in nutrients by ingestion (
phagocytosis, except labyrinthulids) rather than absorption (
osmotrophy, as fungi, labyrinthulids, oomycetes and hyphochytrids). Neither water molds nor slime molds are closely related to the true fungi, and, therefore,
taxonomists no longer group them in the kingdom Fungi. Nonetheless, studies of the oomycetes and myxomycetes are still often included in
mycology textbooks and primary research literature.
Rozellida clade, including the "ex-chytrid" Rozella, is a genetically disparate group known mostly from environmental DNA sequences that is a sister group to fungi. Members of the group that have been isolated lack the chitinous cell wall that is characteristic of fungi. Alternatively,
Rozella can be classified as a basal fungal group.
Mycorrhizal symbiosis between
plants and fungi is one of the most well-known plant–fungus associations and is of significant importance for plant growth and persistence in many ecosystems; over 90% of all plant species engage in mycorrhizal relationships with fungi and are dependent upon this relationship for survival.
The mycorrhizal symbiosis is ancient, dating back to at least 400 million years. It often increases the plant's uptake of inorganic compounds, such as
phosphate from soils having low concentrations of these key plant nutrients. The fungal partners may also mediate plant-to-plant transfer of carbohydrates and other nutrients. Such mycorrhizal communities are called "common
mycorrhizal networks". A special case of mycorrhiza is
myco-heterotrophy, whereby the plant parasitizes the fungus, obtaining all of its nutrients from its fungal symbiont. Some fungal species inhabit the tissues inside roots, stems, and leaves, in which case they are called endophytes. Similar to mycorrhiza, endophytic colonization by fungi may benefit both symbionts; for example, endophytes of grasses impart to their host increased resistance to herbivores and other environmental stresses and receive food and shelter from the plant in return.
With algae and cyanobacteria
Lichens are a symbiotic relationship between fungi and
cyanobacteria. The photosynthetic partner in the relationship is referred to in lichen terminology as a "photobiont". The fungal part of the relationship is composed mostly of various species of
ascomycetes and a few
basidiomycetes. Lichens occur in every ecosystem on all continents, play a key role in
soil formation and the initiation of
biological succession, and are prominent in some extreme environments, including
semiarid desert regions. They are able to grow on inhospitable surfaces, including bare soil, rocks,
tree bark, wood, shells, barnacles and leaves. As in
mycorrhizas, the photobiont provides sugars and other carbohydrates via
photosynthesis to the fungus, while the fungus provides minerals and water to the photobiont. The functions of both symbiotic organisms are so closely intertwined that they function almost as a single organism; in most cases the resulting organism differs greatly from the individual components. Lichenization is a common mode of nutrition for fungi; around 27% of known fungi—more than 19,400 species—are lichenized. Characteristics common to most lichens include obtaining
organic carbon by photosynthesis, slow growth, small size, long life, long-lasting (seasonal)
vegetative reproductive structures, mineral nutrition obtained largely from airborne sources, and greater tolerance of
desiccation than most other photosynthetic organisms in the same habitat.
Organisms that parasitize fungi are known as
mycoparasitic organisms. About 300 species of fungi and fungus-like organisms, belonging to 13 classes and 113 genera, are used as
biocontrol agents against plant fungal diseases. Fungi can also act as mycoparasites or antagonists of other fungi, such as Hypomyces chrysospermus, which grows on
Fungi can also become the target of infection by
Mycotoxins are secondary metabolites (or
natural products), and research has established the existence of biochemical pathways solely for the purpose of producing mycotoxins and other natural products in fungi. Mycotoxins may provide
fitness benefits in terms of physiological adaptation, competition with other microbes and fungi, and protection from consumption (
fungivory). Many fungal secondary metabolites (or derivatives) are used medically, as described under
Human use below.
Ustilago maydis is a pathogenic plant fungus that causes smut disease in maize and
teosinte. Plants have evolved efficient defense systems against pathogenic microbes such as U. maydis. A rapid defense reaction after pathogen attack is the
oxidative burst where the plant produces
reactive oxygen species at the site of the attempted invasion. U. maydis can respond to the oxidative burst with an oxidative stress response, regulated by the gene YAP1. The response protects U. maydis from the host defense, and is necessary for the pathogen's virulence. Furthermore, U. maydis has a well-established recombinational
DNA repair system which acts during mitosis and meiosis. The system may assist the pathogen in surviving DNA damage arising from the host plant's oxidative defensive response to infection.
Cryptococcus neoformans is an encapsulated yeast that can live in both plants and animals. C.neoformans usually infects the lungs, where it is phagocytosed by
alveolar macrophages. Some C.neoformans can survive
inside macrophages, which appears to be the basis for
latency, disseminated disease, and resistance to antifungal agents. One mechanism by which C.neoformans survives the hostile macrophage environment is by up-regulating the expression of genes involved in the oxidative stress response. Another mechanism involves
meiosis. The majority of C.neoformans are mating "type a". Filaments of mating "type a" ordinarily have haploid nuclei, but they can become diploid (perhaps by endoduplication or by stimulated nuclear fusion) to form
blastospores. The diploid nuclei of blastospores can undergo meiosis, including recombination, to form haploid basidiospores that can be dispersed. This process is referred to as monokaryotic fruiting. This process requires a gene called DMC1, which is a conserved homologue of genes recA in bacteria and RAD51 in eukaryotes, that mediates homologous chromosome pairing during meiosis and repair of DNA double-strand breaks. Thus, C.neoformans can undergo a meiosis, monokaryotic fruiting, that promotes recombinational repair in the oxidative, DNA damaging environment of the host macrophage, and the repair capability may contribute to its virulence.
Certain types of cheeses require inoculation of milk curds with fungal species that impart a unique flavor and texture to the cheese. Examples include the
blue color in cheeses such as
Roquefort, which are made by inoculation with Penicillium roqueforti. Molds used in cheese production are non-toxic and are thus safe for human consumption; however, mycotoxins (e.g., aflatoxins,
roquefortine C, patulin, or others) may accumulate because of growth of other fungi during cheese ripening or storage.
Many mushroom species are
poisonous to humans and cause a range of reactions including slight digestive problems,
hallucinations, severe organ failure, and death. Genera with mushrooms containing deadly toxins include Conocybe, Galerina, Lepiota and the most infamous, Amanita. The latter genus includes the destroying angel (
A.virosa) and the death cap (
A.phalloides), the most common cause of deadly mushroom poisoning. The false morel (Gyromitra esculenta) is occasionally considered a delicacy when cooked, yet can be highly toxic when eaten raw.Tricholoma equestre was considered edible until it was implicated in serious poisonings causing
rhabdomyolysis.Fly agaric mushrooms (Amanita muscaria) also cause occasional non-fatal poisonings, mostly as a result of ingestion for its
hallucinogenic properties. Historically, fly agaric was used by different peoples in Europe and Asia and its present usage for religious or
shamanic purposes is reported from some ethnic groups such as the
Koryak people of northeastern
As it is difficult to accurately identify a safe mushroom without proper training and knowledge, it is often advised to assume that a wild mushroom is poisonous and not to consume it.
^Moore RT (1980). "Taxonomic proposals for the classification of marine yeasts and other yeast-like fungi including the smuts". Botanica Marina. 23: 361–373.
^/ˈfʌndʒaɪ/ⓘ, /ˈfʌŋɡaɪ/ⓘ, /ˈfʌŋɡi/ⓘ or /ˈfʌndʒi/ⓘ. The first two pronunciations are favored more in the US and the others in the UK, however all pronunciations can be heard in any English-speaking country.
^Smith JE (1836). Hooker WJ, Berkeley MJ (eds.).
The English Flora of Sir James Edward Smith. Vol. 5, part II: "Class XXIV. Cryptogamia". London, England: Longman, Rees, Orme, Brown, Green & Longman. p. 7. From p. 7: "This has arisen, I conceive, partly from the practical difficulty of preserving specimens for the herbarium, partly from the absence of any general work, adapted to the immense advances which have of late years been made in the study of Mycology."
^"IUCN SSC acceptance of Fauna Flora Funga"(PDF). Fungal Conservation Committee,
IUCN SSC. 2021. Archived from
the original(PDF) on 11 November 2021. Retrieved 11 November 2021. The IUCN Species Survival Commission calls for the due recognition of fungi as major components of biodiversity in legislation and policy. It fully endorses the Fauna Flora Funga Initiative and asks that the phrases animals and plants and fauna and flora be replaced with animals, fungi, and plants and fauna, flora, and funga.
^According to one 2001 estimate, some 10,000 fungal diseases are known. Struck C (2006). "Infection strategies of plant parasitic fungi". In Cooke BM, Jones DG, Kaye B (eds.). The Epidemiology of Plant Diseases. Berlin, Germany: Springer. p. 117.
^Money NP (1998). "Mechanics of invasive fungal growth and the significance of turgor in plant infection". Molecular Genetics of Host-Specific Toxins in Plant Disease: Proceedings of the 3rd Tottori International Symposium on Host-Specific Toxins, Daisen, Tottori, Japan, August 24–29, 1997. Netherlands:
Kluwer Academic Publishers. pp. 261–271.
^Blackwell M, Spatafora JW (2004). "Fungi and their allies". In Bills GF, Mueller GM, Foster MS (eds.). Biodiversity of Fungi: Inventory and Monitoring Methods. Amsterdam:
Elsevier Academic Press. pp. 18–20.
^Brakhage AA, Spröte P, Al-Abdallah Q, Gehrke A, Plattner H, Tüncher A (2004). "Regulation of Penicillin Biosynthesis in Filamentous Fungi". Molecular Biotechnolgy of Fungal beta-Lactam Antibiotics and Related Peptide Synthetases. Advances in Biochemical Engineering/Biotechnology. Vol. 88. Berlin, Heidelberg: Springer. pp. 45–90.
^Pan A, Lorenzotti S, Zoncada A (January 2008). "Registered and investigational drugs for the treatment of methicillin-resistant Staphylococcus aureus infection". Recent Patents on Anti-Infective Drug Discovery. 3 (1): 10–33.
Kolbert, Elizabeth, "Spored to Death" (review of
Emily Monosson, Blight: Fungi and the Coming Pandemic, Norton, 253 pp.; and
Alison Pouliot, Meetings with Remarkable Mushrooms: Forays with Fungi Across Hemispheres, University of Chicago Press, 278 pp.), The New York Review of Books, vol. LXX, no.14 (21 September 2023), pp. 41–42. "Fungi sicken us and fungi sustain us. In either case, we ignore them at our peril." (p. 42.)