Fusarium
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Fusarium verticillioides , secondary crop form of Gibberella moniliformis |
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Fusarium is a genus of the sac fungus . Their teleomorph genera are Albonectria , Cyanonectria , Gibberella and Haematonectria as well as thegenera Dialonectria , Macroconia and Microcera, which formerly belonged to the genus Cosmospora . The type species is Fusarium sambucinum , the anamorphic of Gibberella pulicaris .
Their representatives ( fusaria ) usually grow in plant tissue, for example in food or grain. Many species are parasitic , killing their host ( parasitosis ). The disease is known as fusariosis . Often it affects the root or stem area of the plant. The genus is cosmopolitan . The connection of the Fusarium to its host plant is often very close, which is why the scientific name of the host plant is sometimes included in the species name.
features
Fruiting body-like structures ( conidiomata ) are not formed or consist of pale sporodochia . Sets usually do not exist or are hyaline. The conidia are hyaline and sickle-shaped. They are usually multiple, rarely not or simply septate . They are formed in a slimy mass. Splitting takes place through division at the septa. The conidia carriers ( conidiophores ) are branched or penicillate and hyaline. The conidiogenic cells are phialids or, more rarely, polyphialids and are also hyaline.
Another conidial shape can be formed in air mycelium . In this case, conidiomata and sets are never present. The conidia are hyaline, slimy and not septate to multiple times. The formation takes place in a slimy mass or in chains. The conidiophores are sparsely branched and hyaline. The conidiogenic cells are phialids or polyphialids and are hyaline.
species
The genus Fusarium consists of around 150 species. The mushrooms are very difficult to distinguish from one another. This means that one and the same species with several names appears in the literature. The following list is based on Leslie & Summerell (see literature ). It is not complete, but contains the ecologically most important species as well as other species relevant to laboratory studies.
ecology
The representatives of the genus Fusarium usually grow on plants, also in the litter, on the ground or on lichens . Sometimes humans and animals are also attacked.
In contrast to many other types of mold, the spores are not spread by the wind, but by animals. For this purpose, the spores are enveloped in a sticky liquid, as a result of which larger, sticky clusters of spores form.
Taxonomy
General
Most fusaria belong to the Fungi imperfecti , i.e. H. their main fruit form ( teleomorphs ), which forms meiospores and reproduces sexually, is not known. Fusarium is originally not a natural taxon , but a form taxon, the species of which have only been grouped together on the basis of similarities in morphology and way of life. In the meantime, some species have been separated into other genera, such as Fusicolla .
history
The genus Fusarium was established in 1809 by the natural scientist Heinrich Friedrich Link . In the following time numerous species were described - also because one generally assumed a host specification for the exciting Fusarium. About 1000 species of the genus Fusarium were described by the beginning of the 20th century . Due to the large number of characteristics used and the variety of nutrient media used, determinations were very difficult. In addition, many species are inadequately described and evidence of type is often missing or lost.
In 1935 appeared with Die Fusarien, their description, harmful effects and control. by Hans Wilhelm Wollenweber and Otto August Reinking an important work that organized the concept of the genre. For this purpose, the representatives were limited to 65 species with 77 varieties and shapes and divided into 16 sections. This system is the basis of all subsequent taxonomic processing of the genus. Between 1940 and 1954, William Cowperthwaite Snyder and Hans Nicholas Hansen published a new concept that reduced the number of species to just nine.
Another important work is The Genus Fusarium , published in 1971 by Colin Booth . In 1982 Wolfgang Gerlach and Helgard Nirenberg brought out the work Die Fusarien . This met with clear criticism in the 1980s. Nevertheless, it represents an essential work in the taxonomic research of the genus. Another important publication followed in 1983 by Paul E. Nelson , TA Toussoun and Walter Friedrick Otto Marasas under the title Fusarium Species: An Illustrated Manual for Identification. The work differs in the conception of the species quite clearly from the work of Gerlach and Nirenberg.
meaning
Agriculture
Fusaria are one of the great unsolved problems in agriculture, they are among the most important harmful fungi in grain and maize worldwide. They release the toxins DON and ZEA , which can spoil entire harvests. They cause necrosis on the leaf and stalk, fungal mycelia inside the stalk and stunted grain, which lead to a loss of yield and quality. Furthermore, the germinability of the seeds can be reduced. In addition, the fungi form poisonous metabolic products (mycotoxins), which pollute the harvested crop and can endanger the health of animals and humans. In North America in the late 1990s the annual wheat and barley losses they caused were around $ 1 billion. So far there is no information on this for Europe because there are no relevant studies. The great variety of the Fusarium is astonishing, and in the case of cereals it is not possible to distinguish it by the ear symptoms. 16 different species are known to date on maize alone. This makes fighting them extremely difficult.
Wheat is very susceptible to the less specialized fungal parasite that uses the plant's nutrient flow. Sources of growth, such as harvest residues, should therefore be switched off as far as possible. In addition to field hygiene, fungicides with Fusarium effects and, in particular, the choice of resistant varieties are decisive. Since any weakening, such as heat stress, chemical burns from fertilizers and animal pests, promotes Fusarium, these should be avoided if possible. As soon as the ear becomes infected, a fungal network forms on the inside of the husk and the ovary. Thereafter penetrate infection hyphen into the host tissue, wherein substances, such as DON, which inhibit an immune response of the plant and so the penetration is facilitated.
Agent Green
As agent green of plant-damaging fungus Fusarium oxysporum to coca , opium poppy and cannabis called (not to be confused with the chemical agent green ). The fungus was discovered in the late 1980s as part of a US Department of Agriculture project . The Soviet Union had previously isolated and examined the fungus as a potential biological warfare agent . Samples were stored in a laboratory in Tashkent in what is now Uzbekistan , and further development took place there. According to information from environmental organizations, this agent was supposed to have been used in 2001 in Colombia to decimate the coca harvest. Peru , Ecuador and Florida banned the use of this mushroom. The danger lies in uncontrolled spreading to other plants. The ecological balance in the affected area can be permanently destroyed.
toxicity
Fusarium can produce poisons ( Fusarium toxins ). The mycotoxins formed can be divided into the following three categories: Trichothecenes , Zearalenones and Fumonisins . When taken orally, a representative of the trichothecenes, deoxynivalenol, can lead to acute diseases of the gastrointestinal tract , allergic skin reactions and an impairment of the immune system. Due to their more frequent occurrence in food, there are legal maximum levels for the Fusarium toxins deoxynivalenol, T-2 and HT-2 toxin, zearalenone and fumonisins. Some poisons are so strong that a percentage contamination (e.g. for feed grain) is fatal for some animals.
Food
The fungus Fusarium venenatum is the basis for an industrially produced food that is offered as a vegetarian meat substitute under the trade name Quorn .
medicine
Infections by Fusarium species requiring treatment rarely occur in humans. Antifungal therapy may be carried out with voriconazole , amphotericin B (as L-AmB) or posaconazole .
literature
- Keith Seifert, Gareth Morgan-Jones, Walter Gams, Bryce Kendrick: The Genera of Hyphomycetes . CBS-KNAW Fungal Biodiversity Center, Utrecht 2011, ISBN 978-90-70351-85-4 .
- John F. Leslie, Brett A. Summerell, Suzanne Bullock (Illustr.): The Fusarium Laboratory Manual. Wiley-Blackwell, 2006, ISBN 978-0-8138-1919-8 .
Individual evidence
- ↑ a b c d e T. Graefenhan, H.-J. Schroers, HI Nirenberg, KA Seifert: An overview of the taxonomy, phylogeny and typification of nectriaceous fungi in Cosmospora , Acremonium , Fusarium , Stilbella , and Volutella . In: Amy Rossman, Keith Seifert: Phylogenetic revision of taxonomic concepts in the Hypocreales and other Ascomycota. A tribute to Gary J. Samuels. Studies in Mycology 68, 2011, pp. 79-113. ( PDF; 1.03 MB )
- ^ A b Keith Seifert, Gareth Morgan-Jones, Walter Gams, Bryce Kendrick: The Genera of Hyphomycetes . CBS-KNAW Fungal Biodiversity Center, Utrecht 2011, ISBN 978-90-70351-85-4 , p. 209 .
- ↑ Media release from the agricultural research institute Agroscope Reckenholz-Tänikon ART dated May 14, 2007 ( Memento of the original dated December 14, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Media release from the agricultural research institute Agroscope Reckenholz-Tänikon ART from July 23, 2009
- ↑ Alfred Obst / Klaus Gehring: Grain - diseases, pests, weeds . Publishing house Th. Mann, Gelsenkirchen 2002.
- ↑ Agent Green - Bioweapons in the Drug War
- ↑ Regulation (EG) No. 1881/2006 Appendix Section 2.4-2.7 (consolidated version of March 19, 2018)
- ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , p. 285.
Web links
- FungiQuest - Fungiscope Query Tool
- Comprehensive description ( Memento from February 19, 2014 in the Internet Archive ) (PDF, Spanish; 176 kB)
- Fusarium at doctorfungus.org (English)
- http://www.schimmel-schimmelpilze.de/fusarium.html
- Fusarium Genus Record in the Fungorum Index
- A nose for Fusarium