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Fusarium

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Fusarium
Fusarium verticillioides
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Hypocreales
Family: Nectriaceae
Genus: Fusarium
Link (1809)
Species

List of Fusarium species

Fusarium /fjuˈzɛəriəm/ⓘ is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil microbial community. Some species produce mycotoxins in cereal crops that can affect human and animal health if they enter the food chain. The main toxins produced by these Fusarium species are fumonisins and trichothecenes. Despite most species apparently being harmless, some Fusarium species and subspecific groups are among the most important fungal pathogens of plants and animals.

The name of Fusarium comes from Latin fusus, meaning a spindle.

Taxonomy

The taxonomy of the genus is complex. A number of different schemes have been used, and up to 1,000 species have been identified at times, with approaches varying between wide and narrow concepts of speciation ('lumpers' and 'splitters').[1][2][3]

Phylogenetic studies indicate seven major clades within the genus.[3]

Subdivision

Various schemes have subdivided the genus into subgenera and sections. There is a poor correlation between sections and phylogenetic clades.[3]

Sections previously described include;

  • Arachnites
  • Arthrosporiella
  • Discolour
  • Elegans
  • Eupionnotes
  • Gibbosum
  • Lateritium
  • Liseola
  • Martiella
  • Ventricosum
  • Roseum
  • Spicarioides
  • Sporotrichiella

Species

Selected species include;

Etymology

The name of Fusarium comes from Latin fusus, meaning a spindle.

Pathogen

Fusarium chlamydospores
The image of Fusarium Micro and Macro conidia under 45 X Magnification
Fusarium macroconidia

The genus includes a number of economically important plant pathogenic species.

Fusarium graminearum commonly infects barley if there is rain late in the season. It is of economic impact to the malting and brewing industries, as well as feed barley. Fusarium contamination in barley can result in head blight, and in extreme contaminations, the barley can appear pink.[4] The genome of this wheat and maize pathogen has been sequenced. F. graminearum can also cause root rot and seedling blight. The total losses in the US of barley and wheat crops between 1991 and 1996 have been estimated at $3 billion.[4]

Fusarium oxysporum f.sp. cubense is a fungal plant pathogen that causes Panama disease of banana (Musa spp.), also known as fusarium wilt of banana. Panama disease affects a wide range of banana cultivars, which are propagated asexually from offshoots and therefore have very little genetic diversity. Panama disease is one of the most destructive plant diseases of modern times, and caused the commercial disappearance of the once dominant Gros Michel cultivar. A more recent strain also affects the Cavendish cultivars used as a substitute for Gros Michel. It is considered inevitable that this susceptibility will spread globally and commercially wipe out the Cavendish cultivar, for which there are currently no acceptable replacements.

Fusarium oxysporum f. sp. narcissi causes rotting of the bulbs (basal rot) and yellowing of the leaves of daffodils (Narcissi).

In humans

Some species may cause a range of opportunistic infections in humans. In humans with normal immune systems, fusarial infections may occur in the nails (onychomycosis) and in the cornea (keratomycosis or mycotic keratitis).[5] In humans whose immune systems are weakened in a particular way, (neutropenia, i.e., very low neutrophils count), aggressive fusarial infections penetrating the entire body and bloodstream (disseminated infections) may be caused by members of the Fusarium solani complex, Fusarium oxysporum, Fusarium verticillioides, Fusarium proliferatum and, rarely, other fusarial species.[6]

Use as human food

Fusarium venenatum is produced industrially for use as a human food by Marlow Foods, Ltd., and is marketed under the name Quorn in Europe and North America.

Some consumers of fusarium products have shown food allergies similar in nature to peanut and other food allergies. People with known sensitivities to molds should exercise caution when consuming such products.[7]

Biological warfare

Mass casualties occurred in the Soviet Union in the 1930s and 1940s when Fusarium-contaminated wheat flour was baked into bread, causing alimentary toxic aleukia with a 60% mortality rate. Symptoms began with abdominal pain, diarrhea, vomiting, and prostration, and within days, fever, chills, myalgias and bone marrow depression with granulocytopenia and secondary sepsis occurred. Further symptoms included pharyngeal or laryngeal ulceration and diffuse bleeding into the skin (petechiae and ecchymoses), melena, bloody diarrhea, hematuria, hematemesis, epistaxis, vaginal bleeding, pancytopenia and gastrointestinal ulceration. Fusarium sporotrichoides contamination was found in affected grain in 1932, spurring research for medical purposes and for use in biological warfare. The active ingredient was found to be trichothecene T-2 mycotoxin, and it was produced in quantity and weaponized prior to the passage of the Biological Weapons Convention in 1972. The Soviets were accused of using the agent, dubbed "yellow rain", to cause 6,300 deaths in Laos, Kampuchea, and Afghanistan between 1975 and 1981.[8][9] The "biological warfare agent" was later purported to be merely bee feces,[10][11] but the issue remains disputed.

Following an outbreak of Fusarium oxysporum that affected coca plantations in Peru, and other crops planted in the area, the United States has proposed the use of the agent as a mycoherbicide in drug eradication. In 2000, a proposal was passed to use the agent as part of Plan Colombia. In response to concerns use of the fungus could be perceived as biological warfare, the Clinton Administration "waived" this use of Fusarium. A subsequent law passed in 2006 has mandated the testing of mycoherbicide agents - either Fusarium oxysporum or Crivellia papaveracea - in field trials in U.S. territory.[12] Use of Fusarium oxysporum for these tests has raised concerns because resistant coca from the previous outbreak has been widely cultivated, and the fungus has been implicated in the birth of 31 anencephalic children in the Rio Grande region of Texas in 1991[citation needed], the loss of palm trees in Los Angeles, and eye infections from contact lens solutions.[13] The alternative Crivellia papaveracea is less well known; despite decades of study in the Soviet biowarfare lab in Tashkent, Uzbekistan, the relevant mycotoxins reportedly have not yet been isolated, named, or studied.[12]

Pest

Fusarium has posed a threat to the ancient cave paintings in Lascaux since 1955, when the caves were first opened to visitors. The caves subsequently closed and the threat subsided, but the installation of an air conditioning system in 2000 caused another outbreak of the fungus which is yet to be resolved.[14]

References

  1. ^ Nelson 1994.
  2. ^ Moretti 2009.
  3. ^ a b c Watanabe 2011.
  4. ^ a b Brewing Microbiology, 3rd edition. Priest and Campbell, ISBN 0-306-47288-0
  5. ^ Walsh TJ, Dixon DM (1996). Baron S, et al. (eds.). Spectrum of Mycoses. In: Baron's Medical Microbiology (4th ed.). Univ of Texas Medical Branch. ISBN 0-9631172-1-1. (via NCBI Bookshelf).
  6. ^ Howard DH (2003). Pathogenic Fungi in Humans and Animals (2nd ed.). Marcel Dekker. ISBN 0-8247-0683-8. (via Google Books).
  7. ^ Katona SJ, Kaminski ER (November 2002). "Sensitivity to Quorn mycoprotein (Fusarium venenatum) in a mould allergic patient". Journal of Clinical Pathology. 55 (11): 876–7. doi:10.1136/jcp.55.11.876-a. PMC 1769805. PMID 12401831.
  8. ^ Peraica M, Radic B, Lucic A, Pavlovic M (September 1999). "Toxic effects of mycotoxins in humans" (PDF). Bulletin of the World Health Organization. 77 (7): 754–66.{{cite journal}}: CS1 maint: year (link)
  9. ^ Drug Policy Alliance (2006). "Repeating mistakes of the past: another mycoherbicide research bill" (PDF). Archived from the original (PDF) on 4 February 2009. Retrieved 2007-05-27. {{cite web}}: |author= has generic name (help); Unknown parameter |dead-url= ignored (|url-status= suggested) (help)
  10. ^ Earl C (1984). "Yellow rain: Thai bees' faeces found". Nature. 308 (5959): 485. doi:10.1038/308485b0. PMID 6709055.
  11. ^ Marshall E (July 1986). "Yellow rain evidence slowly whittled away". Science. 233 (4759): 18–9. doi:10.1126/science.3715471. PMID 3715471.
  12. ^ a b Center for International Policy, Drug Policy Alliance, Amazon Alliance, Institute for Policy Studies, Washington Office on Latin America. "Evaluating Mycoherbicides for Illicit Drug Crop Control: Rigorous Scientific Scrutiny is Crucial" (PDF). Archived from the original (PDF) on 25 June 2008. {{cite web}}: |author= has generic name (help); Unknown parameter |dead-url= ignored (|url-status= suggested) (help)CS1 maint: multiple names: authors list (link)
  13. ^ Imamura Y, Chandra J, Mukherjee PK, Lattif AA, Szczotka-Flynn LB, Pearlman E, Lass JH, O'Donnell K, Ghannoum MA (January 2008). "Fusarium and Candida albicans biofilms on soft contact lenses: model development, influence of lens type, and susceptibility to lens care solutions". Antimicrobial Agents and Chemotherapy. 52 (1): 171–82. doi:10.1128/AAC.00387-07. PMC 2223913. PMID 17999966.
  14. ^ Rinaldi A (November 2006). "Saving a fragile legacy. Biotechnology and microbiology are increasingly used to preserve and restore the world's cultural heritage". EMBO Reports. 7 (11): 1075–9. doi:10.1038/sj.embor.7400844. PMC 1679785. PMID 17077862.

Bibliography

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