Amyloid layer fungi
| Amyloid layer fungi | ||||||||||||
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Juniper layer mushroom ( Amylostereum laevigatum ) on European yew tree ( Taxus baccata ) |
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Amylostereaceae | ||||||||||||
| Boidin , Mugnier & Canales | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Amylostereum | ||||||||||||
| Boidin |
The amyloid layer fungi ( Amylostereum ) are the only genus of the family of amyloid layer fungus relatives (Amylostereaceae). The genus comprises four species of fungi that feed on living or dead coniferous wood as wood decomposers and parasites . Amyloid layer fungi cause white rot in wood by breaking down the tissue component lignin . They form crust-like, sometimes wavy fruiting bodies on the bark surface of the trees they infest , which are similar to those of the layer fungi ( stereum ).
Three species of the genus are symbionts of wood wasps of the genera Sirex and Urocerus , which attack conifers and serve as food for their larvae. The brown felted layer fungus ( A. areolatum ) in connection with the blue spruce wasp ( S. noctilio ) has gained in importance as a forest pest.
The type species of the genus is the fir layer mushroom ( A. chailletii ).
features
Macroscopic features
Amyloid layer fungi form crusty, dry and leathery-corky fruiting bodies on the bark of infested trees. These fruit bodies are 0.5–1.5 mm thick, very irregularly shaped and can cover large areas on the bark or only appear as small spots. They sit directly on the bark and stick out at the edges in most species. The ocher, gray or brownish fruit layer ( hymenium ) is smooth to warty and turned outwards. In all species, except for the juniper layer fungus ( A. laevigatum ), it is limited by the upturned (effuso-reflex) edge of the fungus. This has a felty surface (a so-called tomentum ) and is usually dirty brown in color. In some specimens it protrudes significantly and forms a kind of roof over the fruiting body; when it completely encloses it, cup-like structures can form.
Microscopic features
Amyloid layer mushrooms have a dimitic trama , that is, two types of hyphae are present in their mushroom flesh . The first type is made up of brownish skeletal hyphae, which ensure the stability of the fruiting body. They run parallel to the cortex and often bend like a hairpin in their course , so that the loops form thick-walled, cystid-like structures, so-called pseudocystids. Generative hyphae form the second type. They are translucent ( hyaline ) and are used for the growth of the fungus. Real cystids arise in the hymenium and the layer directly below it, the subhymenium. Both pseudocystids and cystids are encrustinated, that is, they have crystal-like structures at the tip.
In all species apart from the juniper layer fungus, a thin separating layer called the cortex runs between the hymenium and the tomentum. It is also present in many other layer fungi (in the broader sense) and is responsible for the fact that the edges of the fruiting body bend up. Since this cortex is missing in the juniper layer fungus, its fruiting body lies flat against the bark.
The basidia measure 15-25 × 3.5-5.5 µm and have a slender, club-like shape. A spore sits on each of its four sterigms . The spores are narrow ellipsoidal or cylindrical in shape. Its surface is smooth and its walls are thin. They are colorless and hyaline, but when iodine is added they turn bluish or purple. This property distinguishes the amyloid layer fungi from many other species, which look very similar to them outwardly, and gives the genus its name.
distribution
The distribution area of the amyloid layer fungi originally only included the Holarctic with North America and Eurasia and the Neotropical with Central and South America. With the introduction of the brown felted layer fungus and its symbiote, the blue spruce wasp ( Sirex noctilio ), the genus can now be found on all continents with the exception of Antarctica.
The fir layer mushroom is widespread in North America and Eurasia in the temperate climate zone. The juniper layer fungus can also be found in temperate Eurasia, but it is unclear how widespread the species is in North America. The brown felted layer fungus is originally only native to North Africa and Eurasia; however, it was introduced in Australia, New Zealand, southern Africa, and South and North America during the 20th century. Only Amylostereum ferreum is originally native to the tropics and is widespread in Brazil and the Caribbean.
ecology
Usually, amyloid layer fungi only attack dead or felled wood from conifers. However, three species - brown felt, juniper and fir layer fungus - also form symbioses with wood wasps (Siricidae), which infect living trees as well as freshly felled trees and infect them with the fungi. These are the genera Sirex and Urocerus , which keep oidia (hyphae of fungi split into spores) in special abdominal organs. The wood wasps infect trees by injecting a phytotoxic secretion under the bark of the tree and at the same time injecting fungal spores into the hole. The secretion weakens the tree and briefly reduces its immune system, which allows the amyloid layer fungi to spread along the xylem . Infection with amyloid layer fungi fulfills two functions for the wasps: First, it enables the larvae to eat because the white rot softens the wood; at the same time, the mycelium of the fungi serves as food for the larvae. After the larva has pupated, it takes up the mycelium of the amyloid layer fungus again in its body, in order to later - if female - lay it down with their eggs. The fungus benefits from the symbiosis because it can spread faster and more effectively than by flying spores and also does not have to develop any fruiting bodies. Nevertheless, amyloid layer fungi also develop fruiting bodies in the wild, with the distribution by wood wasps clearly predominating in the corresponding species. Amylostereum ferreum, on the other hand, regularly forms fruiting bodies.
Host spectrum
The host range of the amyloid layer fungi includes several, sometimes very different genera of the conifers (Coniferales). The fir layer fungus mainly affects pine trees such as firs ( Abies ) and spruces ( Picea ), but also cedars ( Cedrus ) and Douglas firs ( Pseudotsuga ). The brown felted layer mushroom has a similar host range, which mainly uses firs, sickle firs ( Cryptomeria ), larches ( Larix ), spruces, pines ( Pinus ) and Douglas firs as hosts. While spruce dominates as hosts in the original range, this species is mostly found in pines in the rest of the world. The host range of the juniper layer fungus includes cypress plants such as juniper ( Juniperus ) or cypress trees ( Cupressus ) and with the European yew ( Taxus baccata ), a taxopsida species that does not belong to the cypress family. Amylostereum ferreum , on the other hand, is only known from Neotropical stone slices ( Podocarpus ).
Infestation symptoms
Amyloid layer fungi are white rot pathogens . They break down the lignin of the host wood, which causes the affected wood areas to lose stability and take on a fibrous structure. This is accompanied by a bleaching of the tissue, since brown pigments are contained in the lignin. It spreads in the wood mainly along the transport channels in the xylem . In the longitudinal section there is therefore a vertical red rot , in which pale, infested areas contrast with intact wood. Factors that indicate an infestation with wood wasps, the symbionts of some species, are circular exit holes in the bark and acute stress from drought, which is reflected in hanging, falling or browning needles.
species
| Amyloid layer fungi ( amylostereum ) |
Taxonomy and research history
The amyloid layer fungi have long been assigned to the genus of layer fungi ( stereum ). This classification was based primarily on the layered structure of the fruiting bodies and the way of life that is very similar to the layered mushrooms. In 1958 Jacques Boidin separated the amyloid layer mushrooms from the layer mushrooms and put them in a separate genus. He justified this decision mainly with microscopic differences such as the amyloid spores and the encrusted cystids of the amyloid layer fungi. As a scientific generic name, he chose Amylostereum , which corresponds to the German name. Although the type species of the genus, the fir layer mushroom, was originally described as Trichocarpus ambiguus , the genus name Trichocarpus was already used in 1958 for a genus of the mallow family .
In 1998 Boidin placed the amyloid layer fungi on the basis of DNA analysis in a separate, monotypic family of amyloid layer fungus relatives (Amylostereaceae), which he included in the Hericiales order . However, later investigations supported the original assignment to the Russulales .
External system
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The classification of the amyloid layer fungi is not fully understood. The closest relatives - depending on the investigation - are either Echinodontium tinctorium with a large part of the genus Echinodontium or the cup coral ( Artomyces pyxidatus ). The results of the previous DNA analyzes mostly indicate a close relationship to Echinotontium . However, the results of some other studies contradict this in part. Only the assignment to the Russulales is considered certain. A classification of the genus Amylostereum in the family Echinodontiaceae is suggested by some authors.
Development history and internal system
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Within the genus, the similarity between the pine layer mushroom ( A. chailletii ) and the brown felt layer mushroom ( A. areolatum ) caused confusion. Since the fruiting bodies of the two species only differ externally in size, German Josef Krieglsteiner , for example, assumes that they are one and the same species in different stages of age. In experiments with cultures of the species, however, it was shown that the mycelium of the fir layer fungus, juniper layer mushroom ( A. laevigatum ) and A. ferreum could be partially combined, but the mycelium of the brown felted layer fungus was incompatible with that of all other species; A. laevigatum and A. chailletii were incompatible. Boidin speculates that the common ancestor of all amyloid layer fungi used stone slices as host. This genus was also at home in Europe until the Tertiary , but died out there, so that the amyloid layer fungi specialized in other conifers and disintegrated into several species. Only A. ferreum remained specialized in stone slices in South America.
Both compatibility tests and DNA analyzes show that the brown felted layer fungus separated from the other amyloid layer fungi very early. The other three species, however, only separated recently and are therefore still partially compatible with each other. A. ferreum and A. laevigatum formed a common mycelium in 59% of the cases, A. ferreum and A. chailletii in only 44% of the cases. A so far not identified fungus from the genus Amylostereum is located between A. laevigatum and A. ferreum in DNA analyzes . This is remarkable in that this fungus comes from the mycetangia of a North American wood wasp, while A. laevigatum has not been observed as a symbiont of wood wasps in either North America or Europe. The fungus may be a species of its own or a subtaxon of A. laevigatum . Since A. areolatum and A. chailletii reproduce mainly asexually via the symbiosis with wood wasps, the genetic variability within these species is extremely low.
Ecological and economic importance
In their original home, all species are only of minor importance as forest pests. The wood wasp infestation does not take on any major proportions and is almost insignificant compared to other pests. In the case of sexual reproduction via fruiting bodies, the infection rates are even lower because the wasps are no longer used as vectors. On top of that, amyloid layer fungi on their own usually cannot attack healthy trees. They therefore mostly act as decomposers of dead wood . Pine monocultures in Australia, New Zealand, Africa and South America, however, have proven to be susceptible to the blue spruce wasp ( Sirex noctilio ) and the associated brown felted layer fungus ( A. areolatum ). The phytotoxic secretion of the wasp, its larvae and the fungus work together very effectively and sometimes lead to tree mortality rates of up to 80%. This is mainly a consequence of the insufficient water and nutrient supply of the trees, which can only cope with the drought stress caused by the infestation with difficulty. As a countermeasure, cultures of the nematode Deladenus sircidicola have been inoculated into trees since the 1980s . This parasite feeds on the mycelium of the brown felted layer fungus and is therefore a food competitor of the wasp larvae. In addition, it attacks the insects and leads to sterility in the females , whereupon only male larvae hatch from their eggs. This method has been in the fight against Sirex - Amylostereum proved relatively successful complex.
swell
literature
- J. Boidin: Hétérobasidiomycètes saprophytes et Homobasidiomycètes résupinés: V.- Essai sur le Genre Stereum Pers. ex SF Gray . In: Revue de Mycologie 23, 1958. pp. 318-346.
- J. Boidin, P. Lanquetin: Le genre Amylostereum (Basidiomycetes) intercompatibilités entre espèces allopatriques. In: Bulletin de la Societé Mycologique de France 100, No. 2, 1984. pp. 211-236.
- J. Boidin, J. Munier, R. Canales: Taxonomie molecular des Aphylloporales . In: Mycotaxon 66, 1998. pp. 445-491.
- O. Eichhorn: Siricoidea . In: Wolfgang Schwenke (Ed.): The forest pests of Europe. Volume 4: Hymenoptera and Diptera. Hamburg 1982. ISBN 3-490-11016-1 , pp. 196-231.
- Hermann Jahn : Steroids mushrooms in Europe (Stereaceae Pil. Emend. Parm. And others, Hymenochaete) with special consideration of their occurrence in the Federal Republic of Germany. In: Westfälische Pilzbriefe 8, No. 4–7 1971. pp. 69–119 (online as PDF; 3.08 MB ).
- German Josef Krieglsteiner (Ed.): The large mushrooms of Baden-Württemberg . Volume 1: General Part. Stand mushrooms: jelly, bark, prick and pore mushrooms. Ulmer, Stuttgart 2000, ISBN 3-8001-3528-0 , pp. 150-153.
- Ellen Larsson, Karl-Henrik Larsson: Phylogenetic relationships of russuloid basidiomycetes with emphasis on aphyllophoralean taxa. In: Mycologia 95, No. 6/2003. Pp. 1037-1065. (Online as PDF )
- Bernard Slippers, Brenda D. Wingfield, Teresa A. Coutinho, Michael J. Wingfield: Relationships among Amylostereum species associated with siricid woodwasps inferred from mitochondrial DNA sequences. In: Mycologia 92, No. 5, 2000. pp. 955-963.
- Bernard Slippers, Michael J. Wingfield, Brenda D. Wingfield, Teresa A. Coutinho: DNA sequence and RFLP data reflect geographical spread and relationships of Amylostereum areolatum and its insect vectors. In: Molecular Ecology 11, 2002. pp. 1845-1854.
- Bernard Slippers, Teresa A. Coutinho, Brenda D. Wingfield and Michael J. Wingfield: A review of the genus Amylostereum and its association with woodwasps. In: South African Journal of Science 99, 2003. pp. 70-74. (Online as PDF )
- Bernard Slippers, Teresa A. Coutinho, Brenda D. Wingfield and Michael J. Wingfield: Genetic linkage map for Amylostereum areolatum reveals an association between vegetative growth and sexual and self-recognition . In: Fungal Genetics and Biology 46, 2009. pp. 632-641.
- Masanobu Tabata, Yasuhisa Abe: Amylostereum laevigatum associated with a horntail, Urocerus antennatus. In: Mycoscience 40, No. 5 1993. doi : 10.1007 / BF02461032 , pp. 535-539.
- Masanobu Tabata, Thomas C. Harrington, Wei Chen, Yasuhisa Abe: Molecular phylogeny of species in the genera Amylostereum and Echinodontium. In: Mycoscience 41, 2000. pp. 585-593.
- Proposed Program for Management of the Woodwasp Sirex noctilio Fabricus (Hymenoptera: Siricidae). United States Department of Agriculture, 2007.
Web links
- Amylostereum on MycoBank . www. mycobank.org, January 1, 2000.
Individual evidence
- ↑ a b c d Krieglsteiner 2000 , p. 150.
- ↑ a b c d Jahn 1971 , pp. 89-103.
- ↑ Boidin 1984 , p. 221.
- ↑ a b Boidin 1984 , pp. 214-218.
- ↑ Tabata & Abe 1993 , p. 538.
- ↑ a b Eichhorn 1982 , p. 202.
- ↑ Boidin 1958 , pp. 344-345.
- ↑ Boidin 1998 , p. 478.
- ↑ a b c d Larsson & Larsson 2003 , pp. 1055-1058.
- ↑ a b Slippers et al. 2000 , p. 961.
- ↑ a b Slippers et al. 2003 , p. 72.
- ↑ Krieglsteiner 2000 , p. 151.
- ↑ a b Boidin 1998 , pp. 478-479.
- ↑ Slippers et al. 2003 , p. 73.
- ↑ USDA 2007 , p. 29.
