Trichoderma

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Trichoderma
T. harzianum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Hypocreales
Family: Hypocreaceae
Genus: Trichoderma
Pers.
(1801)
Type species
Trichoderma fuliginoides
Pers. (1801)
Species

see List of Trichoderma species

Trichoderma is a

endophytic relationships with several plant species.[2] The genomes of several Trichoderma species have been sequenced and are publicly available from the JGI.[3]

Taxonomy

The genus was described by

mold.[4]

Subdivision

In 1991, Bissett divided the genus into five sections, partly based on the aggregate species described by Rifai:[5]

  • Pachybasium (20 species)
  • Longibrachiatum (10 species)
  • Trichoderma
  • Saturnisporum (2 species)
  • Hypocreanum

With the advent of molecular markers from 1995 onwards, Bissett's scheme was largely confirmed but Saturnisporum was merged with Longibrachiatum. While Longibrachiatum and Hypocreanum appeared

clades.[4]
Consequently, the formal description of sections has been largely replaced by informal descriptions of clades, such as the Aureoviride clade or the Gelatinosum clade.

Species

Main article: List of Trichoderma species

The belief that Trichoderma was

monotypic persisted until the 1969 work of Rifai, who recognised nine species.[6]
There are currently 89 accepted species in the genus Trichoderma.
anamorphs.[6]

Characteristics

Cultures are typically fast-growing at 25–30 °C (77–86 °F), but some species of Trichoderma will grow at 45 °C (113 °F). Colonies are transparent at first on media such as cornmeal dextrose agar (CMD) or white on richer media such as potato dextrose agar (PDA). Mycelium are not typically obvious on CMD,

conidia
typically form within one week in compact or loose tufts in shades of green or yellow or less frequently white. A yellow pigment may be secreted into the agar, especially on PDA. Some species produce a characteristic sweet or 'coconut' odor.

Conidiophores are highly branched and thus difficult to define or measure, loosely or compactly tufted, often formed in distinct concentric rings or borne along the scant aerial hyphae. Main branches of the conidiophores produce lateral side branches that may be paired or not, the longest branches distant from the tip and often phialides arising directly from the main axis near the tip. The branches may rebranch, with the secondary branches often paired and longest secondary branches being closest to the main axis. All primary and secondary branches arise at or near 90° with respect to the main axis. The typical Trichoderma conidiophore with paired branches assumes a pyramidal aspect. Typically the conidiophore terminates in one or a few phialides. In some species (e.g., T. polysporum) the main branches are terminated by long, simple or branched, hooked, straight or sinuous, septate, thin-walled, sterile or terminally fertile elongations. The main axis may be the same width as the base of the phialide or it may be much wider.

subglobose. Phialides may be held in whorls, at an angle of 90° with respect to other members of the whorl, or they may be variously penicillate (gliocladium-like). Phialides may be densely clustered on a wide main axis (e.g., T. polysporum, T. hamatum), or they may be solitary (e.g., T. longibrachiatum
).

T. virens, T. flavofuscum). Conidia of most species are ellipsoidal, 3–5 x 2–4 µm (L/W = > 1.3); globose conidia (L/W < 1.3) are rare. Conidia are typically smooth but tuberculate to finely warted conidia are known in a few species. Conidia appear colorless to green, smooth to rough, and are in moist conidial masses, variable in shape and size, small, 2.8– 4.8 mm for common species. Conidiophores branch repeatedly, bearing clusters of phialides terminally in most cases.[7]

conidiophores
that are verticillately branched and that bear conidia in a drop of clear green liquid at the tip of each phialide.

Chlamydospores may be produced by all species, but not all species produce chlamydospores on CMD at 20 °C within 10 days. Chlamydospores are typically unicellular subglobose and terminate short hyphae; they may also be formed within hyphal cells. Chlamydospores of some species are multicellular (e.g., T. stromaticum).

Trichoderma genomes appear to be in the 30–40 Mb range, with approximately 12,000 genes being identifiable.

Teleomorph

Teleomorphs of Trichoderma are species of the ascomycete genus Hypocrea
. These are characterized by the formation of fleshy, stromata in shades of light or dark brown, yellow or orange. Typically the stroma is discoidal to pulvinate and limited in extent but stromata of some species are effused, sometimes covering extensive areas. Stromata of some species (Podostroma) are clavate or turbinate. Perithecia are completely immersed. Ascospores are bicellular but disarticulate at the septum early in development into 16 part-ascospores so that the ascus appears to contain 16 ascospores. Ascospores are hyaline or green and typically spinulose. More than 200 species of Hypocrea have been described but few have been grown in pure culture and even fewer have been described in modern terms.

Occurrence

Trichoderma colony in nature

Trichoderma species are frequently isolated from forest or agricultural soils at all latitudes. Hypocrea species are most frequently found on bark or on decorticated wood but many species grow on bracket fungi (e.g. H. pulvinata), Exidia (H. sulphurea) or bird's nest fungi (H. latizonata) or agarics (H. avellanea).

Biocontrol agent

Several strains of Trichoderma have been developed as biocontrol agents against fungal diseases of plants.[8] The various mechanisms include antibiosis, parasitism, inducing host-plant resistance , and competition. Most biocontrol agents are from the species T. asperellum, T. harzianum, T. viride, and T. hamatum. The biocontrol agent generally grows in its natural habitat on the root surface, and so affects root disease in particular, but can also be effective against foliar diseases.

Causal agent of disease

button mushrooms.[9][10] Trichoderma viride is the causal agent of green mold rot of onion.[11] A strain of Trichoderma viride is a known cause of dieback of Pinus nigra seedlings.[12]

Toxic house mold

The common

primary prevention the only management option.[13][14][15]

Medical uses

Cyclosporine A (CsA), a calcineurin inhibitor produced by the fungi Trichoderma polysporum,[16] Tolypocladium inflatum, and Cylindrocarpon lucidum, is an immunosuppressant prescribed in organ transplants to prevent rejection.[17]

Industrial use

Trichoderma, being a saprophyte adapted to thrive in diverse situations, produces a wide array of enzymes. By selecting strains that produce a particular kind of enzyme, and culturing these in suspension, industrial quantities of enzyme can be produced.

See also

References

  1. S2CID 17404703.[permanent dead link
    ]
  2. PMID 21091159
    .
  3. ^ "Home - Trichoderma atroviride".
  4. ^
    PMID 15633245
    .
  5. doi:10.1139/b91-298
    .
  6. ^
    PMID 18943925
    .
  7. ISBN 9780471730934
    .
  8. PMID 18943924
    .
  9. ^ Beyer, W.M.; Wuest, P.J.; Anderson, M.G. "Green mold of Mushrooms". Pennsylvania State University. Retrieved 2007-08-02. Pennsylvania State University extension bulletin
  10. JSTOR 3761854
    .
  11. ISBN 978-0-12-384733-1
    , retrieved 2024-02-27
  12. PMID 30699733
    .
  13. ^ Reason Discovered for the Toxicity of Indoor Mould – ScienceDaily (Oct. 12, 2012) : https://www.sciencedaily.com/releases/2012/10/121012074655.htm
  14. PMID 22994321
    .
  15. ^ “Trilongins” Offer Insight into Mold Toxicity Archived 2016-03-11 at the Wayback Machine Environmental health perspectives 2/2013.
  16. S2CID 26876550
    .
  17. PMID 19694312
    .
  18. ^ "Home - Trichoderma reesei v2.0".
  19. doi:10.1016/S0032-9592(98)00128-9
    .
  20. doi:10.1016/j.enzmictec.2006.06.013
    .

Bibliography

Public Domain This article incorporates public domain material from websites or documents of the United States Department of Agriculture.

External links

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