Ganoderma

''Ganoderma'' is a genus of polypore fungi in the family Ganodermataceae that includes about 80 species, many from tropical regions. They have a high genetic diversity and are used in traditional Asian medicines. ''Ganoderma'' can be differentiated from other polypores because they have a double-walled basidiospore. They may be called ''shelf mushrooms'' or bracket fungi.

Etymology

The name ''Ganoderma'' is derived from the Greek ''ganos''/γάνος "brightness, sheen", hence "shining" and ''derma''/δέρμα "skin".

History

The genus ''Ganoderma'' was established as a genus in 1881 by Karsten and included only one species, ''G. lucidum'' (Curtis) Karst. Previously, this taxon was characterized as ''Boletus lucidus'' Curtis (1781) and then ''Polyporus lucidus'' (Curtis) Fr. (1821) (Karsten 1881). The species ''P. lucidus'' was characterized by having a laccate (shiny or polished) pileus and stipe, and this is a character that Murrill suspected was the reason for Karsten's division because only one species was included, ''G. lucidum'' .Murrill, W. A. 1902. The Polyporaceae of North America, genus I ''Ganoderma''. Bull. Torrey Bot. Club 29:599-608. Patouillard revised Karsten's genus ''Ganoderma'' to include all species with pigmented spores, adhering tubes and laccate crusted pilei, which resulted with a total of 48 species classified under the genus ''Ganoderma'' in his 1889 monograph.Atkinson, G. F. 1908. Observations on ''Polyporus lucidus'' Leys and some of its Allies from Europe and North America. Botanical Gazette 46:321-338. Until Murrill investigated ''Ganoderma'' in North America in 1902, previous work had focused solely on European species including, for example, ''G. lucidum, G. resinaceum'' Boud. (1890) and ''G. valesiacum'' Boud. (1895).Murrill, W. A. 1908. Agaricales (Polyporaceae). North Amer. Flora 9:73-131.

Description

''Ganoderma'' are characterized by basidiocarps that are large, perennial, woody brackets also called "conks". They are lignicolous and leathery either with or without a stem. The fruit bodies typically grow in a fan-like or hoof-like form on the trunks of living or dead trees. They have double-walled, truncate spores with yellow to brown ornamented inner layers.

Phylogeny

The genus was named by Karsten in 1881. Members of the family Ganodermataceae were traditionally considered difficult to classify because of the lack of reliable morphological characteristics, the overabundance of synonyms, and the widespread misuse of names. Until recently, the genus was divided into two sections – ''Ganoderma'', with a shiny cap surface (like ''Ganoderma lucidum''), and ''Elfvingia'', with a dull cap surface (like '' Ganoderma applanatum'').

Phylogenetic analysis using DNA sequence information have helped to clarify our understanding of the relationships amongst ''Ganoderma'' species. The genus may now be divided into six monophyletic groups:

*''G. colossus'' group
*'' G. applanatum'' group
*'' G. tsugae'' group
*Asian '' G. lucidum'' group
*'' G. meredithiae'' group
*''G. resinaceum'' group

With the rise of molecular phylogenies in the late 20th century, species concept hypotheses were tested to determine the relatedness amongst the nuanced morphological variabilities of the laccate ''Ganoderma'' taxa. In 1995, Moncalvo ''et al'' constructed a phylogeny of the rDNA, which was the universally accepted locus at that time, and found five major clades of the laccate species amongst the 29 isolates tested.Moncalvo, J.-M., Wang, H.-F., and Hseu, R.-S. 1995. Gene phylogeny of the ''Ganoderma lucidum'' complex based on ribosomal DNA sequences. Comparison with traditional taxonomic characters. Mycological Research 99:1489-1499. It turned out that ''G. lucidum'' was not a monophyletic species, and further work needed to be done to clarify this taxonomic problem. They also found that ''G. resinaceum'' from Europe, and the North American G. lucidum''', which Adaskaveg and Gilbertson found to be biologically compatible ''in vitro'', did not cluster together.Adaskaveg, J. E., and Gilbertson, R. L. 1986. Cultural studies and genetics of sexuality of ''Ganoderma lucidum'' and ''G. tsugae'' in relation to the taxonomy of the ''G. lucidum'' complex. Mycologia:694-705. Moncalvo ''et al.'' reject biological species complexes as a sole tool to distinguish a taxon, and suggested using a combination between biological and phylogenetic species concepts to define unique ''Ganoderma'' taxa.

In 1905, American mycologist William Murrill delineated the genus ''Tomophagus'' to accommodate the single species ''G. colossus'' (then known as ''Polyporus colossus'') which had distinctive morphological features that did not fit in with the other species. Historically, however, ''Tomophagus'' has generally been regarded as a synonym for ''Ganoderma''. Nearly a century later, phylogenetic analyses vindicated Murrill's original placement, as it has shown to be a taxonomically distinct appropriate genus.

Significance

Crop diseases

Some ''Ganoderma'' species can cause major long-term crop losses, especially with trees:
*'' G. orbiforme (= G. boninense)'', '' G. zonatum'' and '' G. miniatocinctum'' are responsible for basal stem rot disease in Asian oil palm plantations.
*'' G. philippii'' and '' G. pseudoferreum'' are responsible for the root rot of cacao, coffee, rubber and tea trees.

Industry

''Ganoderma'' are wood-decaying fungi with a cosmopolitan distribution. They can grow on both coniferous and hardwood species. They are white-rot fungi with enzymes that allow them to break down wood components, such as lignin and cellulose. There has been significant research interest on the wood-degrading enzymes of ''Ganoderma'' species for industrial applications, such as biopulping and bioremediation.

Phytochemistry

For centuries, ''Ganoderma'' species have been used in traditional medicine in many parts of Asia. These species are often mislabeled as G. lucidum''', although genetic testing has shown this to be multiple species such as ''G. lingzhi, G. multipileum,'' and ''G. sichuanense''. Several species of ''Ganoderma'' contain diverse phytochemicals with undefined properties in vivo, such as triterpenoids and polysaccharides, an area of investigation under basic research.

Although various ''Ganoderma'' species are used in traditional medicine for supposed benefits and have been investigated for their potential effects in humans, there is no evidence from high-quality clinical research that ''Ganoderma'' as a whole mushroom or its phytochemicals have any effect in humans, such as in treating cancer.

Notable species

*'' Ganoderma applanatum'' - Also known as the artist's conk. An infestation of this species was the main factor in the loss of the Anne Frank Tree.
*'' Ganoderma lingzhi'' - Also known as red reishi, a mushroom used extensively in traditional Asian medicine.
*''Ganoderma lucidum'' - A polypore with limited distribution in Europe and parts of China, often misidentified on products labeled reishi or lingzhi that actually contain '' Ganoderma lingzhi'', because of the persistence of outdated naming conventions.
*'' Ganoderma sinense'' - Also known as black reishi or zizhi.
*'' Ganoderma tsugae'' - A polypore which grows on conifers, especially hemlock, giving it its common name, hemlock varnish shelf. Similar in appearance to ''Ganoderma lucidum'' and a close relative, which typically grows on hardwoods.
*'' Ganoderma microsporum'' - A polypore found in Taiwan with a very small spore size.

See also

* Ganoderic acid

References

{{Taxonbar, from=Q1799774

Ganodermataceae
Polyporales genera
Taxa named by Petter Adolf Karsten