''Exserohilum'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

in the family

Pleosporaceae Pleosporaceae is a family (biology), family of sac fungi. They are pathogenic to humans or saprobic on woody and dead herbaceous stems or leaves. They are generally Teleomorph, anamorph and holomorph, anamorphic species (having an asexual reprod ...

. 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 In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

is ''

Exserohilum turcicum ''Setosphaeria turcica'' (anamorph ''Exserohilum turcicum''; formerly known as ''Helminthosporium turcicum'') is the causal agent of northern corn leaf blight in maize. It is a serious fungal disease prevalent in cooler climates and tropical hig ...

''. This genus is among three

dematiaceous Black yeasts, sometimes also black fungi, dematiaceous fungi, microcolonial fungi or meristematic fungi is a diverse group of slow-growing microfungi which reproduce mostly asexually (fungi imperfecti). Only few genera reproduce by budding cells, ...

that are categorized for containing

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

s leading to diseases like

phaeohyphomycosis Phaeohyphomycosis is a diverse group of fungal infections, caused by dematiaceous fungi whose morphologic characteristics in tissue include hyphae, yeast-like cells, or a combination of these. It can be associated with an array of melanistic fil ...

Morphology

''Exserohilum'' is an asexual organism that reproduces through

spores In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plant ...

. These one-celled reproductive units are concave and can be seen in the

suspensor A suspensor is a temporary anatomical structure in fungi and plants that supports early development. In fungi, it holds the zygospore between hyphae. In plants, it connects the embryo to surrounding tissues and helps position it within the endosp ...

Taxonomy

''Exserohilum'' was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

by K. Leonard and Edna Suggs in 1974 to contain species formerly placed in ''

Bipolaris ''Bipolaris'' is a genus of fungi belonging to the family Pleosporaceae. It was circumscribed by mycologist Robert A. Shoemaker in 1959. It has a cosmopolitan distribution worldwide. Species , the GBIF lists up to 71 species, while Species Fung ...

'' with distinctly protruding

hila Hila may refer to: *plural form of Hilum (disambiguation), Hilum *Village in Israel: Mitzpe Hila *Hila (given name), in Hebrew * For the Islamic concept of "stratagem", see Ḥiyal *Hila, Ambon, the town on the Indonesian island of Ambon where Fort ...

. 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 A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...

which are

ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a Surface (mathemat ...

al and distoseptate (forming a layer). 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 In botany, sympodial growth is a bifurcating branching pattern where one branch develops more strongly than the other, resulting in the stronger branches forming the primary shoot and the weaker branches appearing laterally. A sympodium, als ...

angled

conidiophore A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an Asexual reproduction, asexual, non-motility, motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word f ...

. 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.

Habitat and distribution

''Exserohilum'' has a

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

, with its species found naturally in warm,

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

, and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

locations. They live on plant material like grasses, rotten wood and in the soil.

Species

Index Fungorum ''Index Fungorum'' is an international project to index all formal names (scientific names) in the fungus kingdom. As of 2015, the project is based at the Royal Botanic Gardens, Kew, one of three partners along with Landcare Research and th ...

lists 26 valid species of ''Exserohilum'': *'' Exserohilum antillanum'' R.F.Castañeda, Guarro & Cano 1995 – Cuba *'' Exserohilum curvatum'' Sivan. & Muthaiyan 1984 – Venezuela *'' Exserohilum curvisporum'' Sivan., Abdullah & B.A.Abbas 1993 – Iraq *'' Exserohilum echinochloae'' Sivan. 1984 – Bangladesh *'' Exserohilum frumentacei'' (Mitra) K.J.Leonard & Suggs 1974 –

Andhra Pradesh Andhra Pradesh (ISO 15919, ISO: , , AP) is a States and union territories of India, state on the East Coast of India, east coast of southern India. It is the List of states and union territories of India by area, seventh-largest state and th ...

;

Bihar Bihar ( ) is a states and union territories of India, state in Eastern India. It is the list of states and union territories of India by population, second largest state by population, the List of states and union territories of India by are ...

;

Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...

;

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

;

Sabah Sabah () is a States and federal territories of Malaysia, state of Malaysia located in northern Borneo, in the region of East Malaysia. Sabah has land borders with the Malaysian state of Sarawak to the southwest and Indonesia's North Kalima ...

*'' Exserohilum fusiforme'' Alcorn 1991 – Queensland *'' Exserohilum gedarefense'' (El Shafie) Alcorn 1983 – Egypt; Sudan *'' Exserohilum heteromorphum'' G.Y.Sun 2005 *'' Exserohilum heteropogonicola'' Sivan. 1984 –

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

;

Uttaranchal Uttarakhand (, ), also known as Uttaranchal ( ; the official name until 2007), is a state in northern India. The state is bordered by Himachal Pradesh to the northwest, Tibet to the north, Nepal to the east, Uttar Pradesh to the south and sout ...

*'' Exserohilum inaequale'' Sivan. 1984 – Nigeria *'' Exserohilum israeli'' Steiman, Guiraud, Seigle-Mur. & Sage 2000 – Israel *'' Exserohilum longirostratum'' (Subram.) Sivan. 1984 – Andhra Pradesh;

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

; France; Haryana; Madhya Pradesh; Nigeria; Northern Territory;

Puerto Rico ; abbreviated PR), officially the Commonwealth of Puerto Rico, is a Government of Puerto Rico, self-governing Caribbean Geography of Puerto Rico, archipelago and island organized as an Territories of the United States, unincorporated territo ...

;

Rajasthan Rajasthan (; Literal translation, lit. 'Land of Kings') is a States and union territories of India, state in northwestern India. It covers or 10.4 per cent of India's total geographical area. It is the List of states and union territories of ...

; Sudan; Uttar Pradesh; Zambia *'' Exserohilum longisporum'' G.Y.Sun 1997 – China *'' Exserohilum mcginnisii'' A.A.Padhye & Ajello 1986 *'' Exserohilum minor'' Alcorn 1986 *'' Exserohilum neoregeliae'' Sakoda & Tsukib. 2011 *'' Exserohilum oryzae'' Sivan. 1987 – Macedonia *'' Exserohilum oryzicola'' Sivan. 1984 *'' Exserohilum oryzinum'' Sivan. 1984 – Egypt *'' Exserohilum parlierense'' W.Q.Chen & Michailides 2002 *'' Exserohilum paspali'' J.J.Muchovej & Nesio 1987 –

Minas Gerais Minas Gerais () is one of the 27 federative units of Brazil, being the fourth largest state by area and the second largest in number of inhabitants with a population of 20,539,989 according to the 2022 Brazilian census, 2022 census. Located in ...

*''Exserohilum phragmitis'' W.P.Wu 1990 *''Exserohilum protrudens'' Alcorn 1988 *''Exserohilum psidii'' Sivan. 1992 – Andhra Pradesh *''Exserohilum sodomii'' Guiraud, Steiman, Seigle-Mur. & Sage 1997 – Israel *''Exserohilum sorghicola'' Sivan. 1987 – Ethiopia

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.

References

External links

{{Taxonbar, from=Q10493219 Dothideomycetes genera Pleosporaceae