Exserohilum

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Exserohilum
Exserohilum turcicum on Zea mays.jpg
Exserohilum turcicum on corn leaf
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Dothideomycetes
Order: Pleosporales
Family: Pleosporaceae
Genus: Exserohilum
K.J.Leonard & Suggs (1974)
Type species
Exserohilum turcicum
(Pass.) K.J.Leonard & Suggs (1974)

Exserohilum is a genus of fungi in the family Pleosporaceae. The Exserohilum species are known for causing blight and human immune system diseases. The sexual reproductive (or ascigerous) states of Exserohilum species are known as Setosphaeria. The type species is Exserohilum turcicum . This genus is among three dematiaceous that are categorized for containing pathogens leading to diseases like phaeohyphomycosis.

Contents

Morphology

Exserohilum is an asexual organism that reproduces through spores. These one-celled reproductive units are concave and can be seen in the suspensor. [1]

Taxonomy

Exserohilum was circumscribed by K. Leonard and Edna Suggs in 1974 to contain species formerly placed in Bipolaris with distinctly protruding hila. [2] Exsero which means stretch out and hilum which refers to the part of the organism. The truncate hila or hilum, protrudes from its distinct conidia which are ellipsoidal and distoseptate (forming a layer). [3]

Colonies of Exserohilum range from the color grey to blackish-brown. The texture varies from suede-like to floccose in texture. The species also have an olivaceous to black reverse. The conidia from which the hilum extends, are either straight, curved, slightly bent or ellipsoidal to fusiform. and are formed on the top through a pore (poroconidia) on an elongated sympodial angled conidiophore. The strong, protruding truncate hilum and the septum above is normally thick and dark. The end cells are paler and the walls finely roughened. The conidial germination of Exserohilum is bipolar. [1]

Habitat and distribution

Exserohilum has a cosmopolitan distribution, with its species found naturally in warm, tropical, and subtropical locations. They live on plant material like grasses, rotten wood and in the soil. [4]

Species

As of October 2015, Index Fungorum lists 26 valid species of Exserohilum: [5]

Clinical significance

Infection cases caused by exposure to Exserohilum are rare, but it's the most well studied detail of the fungi. The three species of Exserohilum that are identified as human pathogens are: Exserohilum rostratum , Exserohilum longirostratum and Exserohilum mcginnisii . Prevailing infections include sinusitis, skin infection and in some rare cases, cerebral abscesses, keratitis, osteomyelitis, prothetic valve endocarditis, and disseminated infection. Reports of human infection by Exserohilum mainly come from warm, tropical and subtropical locations such as southern United States, India, and Israel. [3]

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Setosphaeria rostrata is a heat tolerant fungus with an asexual reproductive form (anamorph) known as Exserohilum rostratum. This fungus is a common plant pathogen, causing leaf spots as well as crown rot and root rot in grasses. It is also found in soils and on textiles in subtropical and tropical regions. Exserohilum rostratum is one of the 35 Exserohilum species implicated uncommonly as opportunistic pathogens of humans where it is an etiologic agent of sinusitis, keratitis, skin lesions and an often fatal meningoencephalitis. Infections caused by this species are most often seen in regions with hot climates like Israel, India and the southern USA.

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Exserohilum oryzicola is a species of fungus in the family Pleosporaceae. Found in Colombia, where it grows on the leaves of Oryza sativa, it was described as new to science in 1984. It is distinguished from other Exserohilum species by its longer and more tapered conidia.

Exserohilum longirostratum is a species of fungus in the family Pleosporaceae. Found in India, it was described as new to science in 1957 as Helminthosporium longirostratum, and transferred to the genus Exserohilum in 1984.

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<i>Cladosporium sphaerospermum</i> Species of fungus

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References

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  3. 1 2 Liu, Dongyou, ed. (2011). Molecular detection of human fungal pathogens. Boca Raton, Fla.: CRC Press. pp. 83–91. ISBN   978-1-4398-1240-2.
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  5. Kirk PM. "Species Fungorum (version 28th September 2015). In: Species 2000 & ITIS Catalogue of Life" . Retrieved 14 October 2015.
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  12. Choudhary, M.; Sardana, H. R.; Bhat, M. N.; Gurjar, M. S. (1 October 2018). "First Report of Leaf Spot Disease Caused by Exserohilum rostratum on Bottle Gourd in India". Plant Disease. 102 (10): 2042. doi: 10.1094/PDIS-02-18-0315-PDN . PMID   30088959.
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  15. 1 2 Sivanesan A. (1987). "Graminicolous species of Bipolaris, Curvularia, Drechslera, Exserohilum and their teleomorphs". Mycological Papers. 158: 1–261.
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Exserohilum in Index Fungorum