Tremellales
Encyclopedia
The Tremellales are an order
of fungi in the class
Tremellomycetes
. The order contains both teleomorphic and anamorphic species
, most of the latter being yeasts. All teleomorphic species in the Tremellales are parasites
of other fungi, though the yeast states are widespread and not restricted to hosts. Basidiocarps (fruit bodies), when produced, are gelatinous.
The order currently comprises 8 families
, containing around 300 valid species. Significant genera
include Tremella
, two species of which are edible
and commercially cultivated, and the yeast genera Cryptococcus
and Trichosporon
, several species of which are human pathogens.
in 1922 for species in which the basidia were "tremelloid" (globose to ellipsoid with vertical or diagonal septa). Rea placed within it one family, the Tremellaceae
, having the same characteristics as the order.
This circumscription was generally accepted until the 1980s. In 1945, however, G.W. Martin
proposed a substantial extension of the order to include all the species within the (now obsolete) class Heterobasidiomycetes except for the rusts
and the smuts
. Martin therefore included within the Tremellales not only the Tremellaceae, but also the Auriculariaceae
, Dacrymycetaceae, Hyaloriaceae
, Phleogenaceae, Septobasidiaceae, Sirobasidiaceae
, and Tulasnellaceae
(including Ceratobasidium
). This extended version of the order was not widely adopted, but was used in a number of publications by Martin himself and, as late as the 1970s, by his student Bernard Lowy.
A more precise revision was undertaken in 1984, when Bandoni used transmission electron microscopy
to investigate the ultrastructure
of the septal pore apparatus in species of the Tremellales. This revealed that Tremella
and its allies were distinct from Exidia
and its allies, despite both groups having tremelloid basidia. Bandoni referred the latter group to the Auriculariales
, restricting the Tremellales to the Tremellaceae, Sirobasidiaceae, and Tetragoniomycetaceae.
(together with its yeast state Cryptococcus
) and the genus Syzygospora should be included within the group, even though species in these genera do not have tremelloid basidia. The Trichosporonaceae, a family of yeasts, is sometimes placed in its own separate order (the Trichosporonales), but current consensus places the family within the Tremellales. Several genera — Sigmogloea, Tremellina, and Xenolachne — whose family placement is uncertain are also included in the order.
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of fungi in the class
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
Tremellomycetes
Tremellomycetes
The Tremellomycetes are a class of dimorphic fungi. Some species have a gelatinous fruiting body or a sacculate parenthesome. There are 3 orders, 11 families, 50 genera, and 377 species in the Tremellomycetes....
. The order contains both teleomorphic and anamorphic species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, most of the latter being yeasts. All teleomorphic species in the Tremellales are parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
of other fungi, though the yeast states are widespread and not restricted to hosts. Basidiocarps (fruit bodies), when produced, are gelatinous.
The order currently comprises 8 families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
, containing around 300 valid species. Significant genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
include Tremella
Tremella
Tremella is a genus of fungi in the family Tremellaceae. All Tremella species are parasites of other fungi and most produce anamorphic yeast states. Basidiocarps , when produced, are gelatinous and are colloquially classed among the "jelly fungi". Over 100 species of Tremella are currently...
, two species of which are edible
Edible mushroom
Edible mushrooms are the fleshy and edible fruiting bodies of several species of fungi. Mushrooms belong to the macrofungi, because their fruiting structures are large enough to be seen with the naked eye. They can appear either below ground or above ground where they may be picked by hand...
and commercially cultivated, and the yeast genera Cryptococcus
Cryptococcus
Cryptococcus is a genus of fungus. Species grow in culture as yeasts. The perfect forms or teleomorphs of Cryptococcus species are filamentous fungi in the genus Filobasidiella...
and Trichosporon
Trichosporon
Trichosporon is a genus of anamorphic fungi in the family Trichosporonaceae. All species of Trichosporon are yeasts with no known teleomorphs . Most are typically isolated from soil, but several species occur as a natural part of the skin microbiota of humans and other animals...
, several species of which are human pathogens.
History
The order Tremellales was created by Carleton ReaCarleton Rea
Carleton Rea was an English mycologist, botanist, and naturalist.-Background and education:Carleton Rea was born in Worcester, the son of the City Coroner. He was educated at The King's School and Magdalen College, Oxford, where he studied law...
in 1922 for species in which the basidia were "tremelloid" (globose to ellipsoid with vertical or diagonal septa). Rea placed within it one family, the Tremellaceae
Tremellaceae
The Tremellaceae are a family of fungi in the order Tremellales. The family is cosmopolitan and contains both teleomorphic and anamorphic genera, most of the latter being yeasts. All teleomorphic species of fungi in the Tremellaceae are parasites of other fungi, though the yeast states are...
, having the same characteristics as the order.
This circumscription was generally accepted until the 1980s. In 1945, however, G.W. Martin
George Willard Martin
George Willard Martin was an American mycologist. He was born in Brooklyn, New York, and received a Bachelor of Literature degree in 1912, and a Master of Science degree in 1915, both from Rutgers University...
proposed a substantial extension of the order to include all the species within the (now obsolete) class Heterobasidiomycetes except for the rusts
Rust (fungus)
Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales. About 7800 species are known. Rusts can affect a variety of plants; leaves, stems, fruits and seeds. Rust is most commonly seen as coloured powder, composed off tiny aeciospores which land on vegetation producing...
and the smuts
Smut (fungus)
The smuts are multicellular fungi, that are characterized by their large numbers of teliospores. The smuts get their name from a Germanic word for dirt because of their dark, thick-walled and dust-like teliospores. They are mostly Ustilaginomycetes and can cause plant disease...
. Martin therefore included within the Tremellales not only the Tremellaceae, but also the Auriculariaceae
Auriculariaceae
The Auriculariaceae are a family of fungi in the order Auriculariales. Species within the family were formerly referred to the "heterobasidiomycetes" or "jelly fungi", since many have gelatinous basidiocarps that produce spores on septate basidia. Around 100 species are known worldwide. All are...
, Dacrymycetaceae, Hyaloriaceae
Hyaloriaceae
The Hyaloriaceae are a family of fungi in the order Auriculariales. Species within the family have gelatinous basidiocarps that produce spores on septate basidia and, as such, were formerly referred to the "heterobasidiomycetes" or "jelly fungi". All appear to be saprotrophic, growing on dead wood...
, Phleogenaceae, Septobasidiaceae, Sirobasidiaceae
Sirobasidiaceae
The Sirobasidiaceae are a family of fungi in the order Tremellales. Taxa are widespread, primarily tropical, and typically grow on wood and bark....
, and Tulasnellaceae
Tulasnellaceae
The Tulasnellaceae are a family of fungi in the order Cantharellales. The family comprises mainly effused fungi formerly referred to the "jelly fungi" or heterobasidiomycetes...
(including Ceratobasidium
Ceratobasidium
Ceratobasidium is a genus of fungi in the order Cantharellales. Basidiocarps are effused and the genus is sometimes grouped among the corticioid fungi, though species also retain features of the heterobasidiomycetes. Rhizoctonia-like anamorphs of Ceratobasidium species are placed in the genus...
). This extended version of the order was not widely adopted, but was used in a number of publications by Martin himself and, as late as the 1970s, by his student Bernard Lowy.
A more precise revision was undertaken in 1984, when Bandoni used transmission electron microscopy
Transmission electron microscopy
Transmission electron microscopy is a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through...
to investigate the ultrastructure
Ultrastructure
Ultrastructure is the detailed structure of a biological specimen, such as a cell, tissue, or organ, that can be observed by electron microscopy...
of the septal pore apparatus in species of the Tremellales. This revealed that Tremella
Tremella
Tremella is a genus of fungi in the family Tremellaceae. All Tremella species are parasites of other fungi and most produce anamorphic yeast states. Basidiocarps , when produced, are gelatinous and are colloquially classed among the "jelly fungi". Over 100 species of Tremella are currently...
and its allies were distinct from Exidia
Exidia
Exidia is a genus of fungi in the family Auriculariaceae. Species are saprotrophic, growing on dead attached or recently fallen wood, and produce gelatinous basidiocarps . The fruit bodies are variously pustular, lobed, button-shaped, or top-shaped...
and its allies, despite both groups having tremelloid basidia. Bandoni referred the latter group to the Auriculariales
Auriculariales
The Auriculariales are an order of fungi in the class Agaricomycetes. Species within the order were formerly referred to the "heterobasidiomycetes" or "jelly fungi", since many have gelatinous basidiocarps that produce spores on septate basidia...
, restricting the Tremellales to the Tremellaceae, Sirobasidiaceae, and Tetragoniomycetaceae.
Current status
Molecular research, based on cladistic analysis of DNA sequences, confirms Bandoni's split between the tremelloid and exidioid fungi and extends the circumscription of the tremelloid group by including several yeast genera whose status was formerly uncertain. Molecular research has also indicated that the genus FilobasidiellaFilobasidiella
Filobasidiella is a genus of fungi in the family Tremellaceae. Species are parasitic on other fungi and do not produce distinct basidiocarps . The genus is the teleomorphic state of the yeast genus Cryptococcus, some species of which are human pathogens.-History:The genus was first described in...
(together with its yeast state Cryptococcus
Cryptococcus
Cryptococcus is a genus of fungus. Species grow in culture as yeasts. The perfect forms or teleomorphs of Cryptococcus species are filamentous fungi in the genus Filobasidiella...
) and the genus Syzygospora should be included within the group, even though species in these genera do not have tremelloid basidia. The Trichosporonaceae, a family of yeasts, is sometimes placed in its own separate order (the Trichosporonales), but current consensus places the family within the Tremellales. Several genera — Sigmogloea, Tremellina, and Xenolachne — whose family placement is uncertain are also included in the order.