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Basidiomycota is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basidiomycota includes these groups: mushrooms, puffballs, stinkhorns, bracket fungi, other polypores, jelly fungi, boletes, chanterelles, earth stars, smuts, bunts, rusts, mirror yeasts, and Cryptococcus, the human pathogenic yeast. Basidiomycota are filamentous fungi composed of hyphae and reproduce sexually via the formation of specialized club-shaped end cells called basidia that normally bear external meiospores. These specialized spores are called basidiospores. However, some Basidiomycota are obligate asexual reproducers. Basidiomycota that reproduce asexually can typically be recognized as members of this division by gross similarity to others, by the formation of a distinctive anatomical feature, cell wall components, and definitively by phylogenetic molecular analysis of DNA sequence data.
Corn smut is a plant disease caused by the pathogenic fungus Ustilago maydis that causes smut on maize and teosinte. The fungus forms galls on all above-ground parts of corn species. It is edible, and is known in Mexico as the delicacy huitlacoche; which is eaten, usually as a filling, in quesadillas and other tortilla-based foods, and in soups.
Aspergillus flavus is a saprotrophic and pathogenic fungus with a cosmopolitan distribution. It is best known for its colonization of cereal grains, legumes, and tree nuts. Postharvest rot typically develops during harvest, storage, and/or transit. Its specific name flavus derives from the Latin meaning yellow, a reference to the frequently observed colour of the spores. A. flavus infections can occur while hosts are still in the field (preharvest), but often show no symptoms (dormancy) until postharvest storage or transport. In addition to causing preharvest and postharvest infections, many strains produce significant quantities of toxic compounds known as mycotoxins, which, when consumed, are toxic to mammals. A. flavus is also an opportunistic human and animal pathogen, causing aspergillosis in immunocompromised individuals.
The smuts are multicellular fungi characterized by their large numbers of teliospores. The smuts get their name from a Germanic word for dirt because of their dark, thick-walled, and dust-like teliospores. They are mostly Ustilaginomycetes and can cause plant disease. The smuts are grouped with the other basidiomycetes because of their commonalities concerning sexual reproduction.
Karnal bunt is a fungal disease of wheat, durum wheat, and triticale. The smut fungus Tilletia indica, a basidiomycete, invades the kernels and obtains nutrients from the endosperm, leaving behind waste products with a disagreeable odor that makes bunted kernels too unpalatable for use in flour or pasta. While Karnal bunt generally does not lead to devastating crop losses, it has the potential to dramatically decrease yield and poses additional economic concerns through quarantines which limit the export of suspected infectious wheat products from certain areas, including the U.S. Several chemical control methods exist for Karnal bunt of wheat, but much work remains to be done in identifying resistant host varieties.
Sugarcane smut is a fungal disease of sugarcane caused by the fungus Sporisorium scitamineum. The disease is known as culmicolous, which describes the outgrowth of fungus of the stalk on the cane. It attacks several sugarcane species and has been reported to occur on a few other grass species as well, but not to a critical amount. The most recognizable characteristic of this disease is a black or gray growth that is referred to as a "smut whip". Resistance to sugarcane smut is the best course of action for management, but also the use of disease free seed is important. On smaller scale operations treatments using hot water and removing infected plants can be effective. The main mode of spore dispersal is the wind but the disease also spreads through the use of infected cuttings. Sugarcane smut is a devastating disease in sugarcane growing areas globally.
Common bunt, also known as hill bunt, Indian bunt European bunt, stinking smut or covered smut, is a disease of both spring and winter wheats. It is caused by two very closely related fungi, Tilletia tritici and T. laevis.
Covered smut of barley is caused by the fungus Ustilago hordei. The disease is found worldwide and it is more extensively distributed than either loose smut or false loose smut.
Loose smut of barley is caused by Ustilago nuda. It is a disease that can destroy a large proportion of a barley crop. Loose smut replaces grain heads with smut, or masses of spores which infect the open flowers of healthy plants and grow into the seed, without showing any symptoms. Seeds appear healthy and only when they reach maturity the following season is it clear that they were infected. Systemic fungicides are the major control method for loose smut.
False loose smut is a fungal disease of barley caused by Ustilago nigra. This fungus is very similar to U. nuda, the cause of loose smut, and was first distinguished from it in 1932.
Gibberella zeae, also known by the name of its anamorph Fusarium graminearum, is a fungal plant pathogen which causes fusarium head blight (FHB), a devastating disease on wheat and barley. The pathogen is responsible for billions of dollars in economic losses worldwide each year. Infection causes shifts in the amino acid composition of wheat, resulting in shriveled kernels and contaminating the remaining grain with mycotoxins, mainly deoxynivalenol (DON), which inhibits protein biosynthesis; and zearalenone, an estrogenic mycotoxin. These toxins cause vomiting, liver damage, and reproductive defects in livestock, and are harmful to humans through contaminated food. Despite great efforts to find resistance genes against F. graminearum, no completely resistant variety is currently available. Research on the biology of F. graminearum is directed towards gaining insight into more details about the infection process and reveal weak spots in the life cycle of this pathogen to develop fungicides that can protect wheat from scab infection.
Tilletia caries is a basidiomycete that causes common bunt of wheat. The common names of this disease are stinking bunt of wheat and stinking smut of wheat. This pathogen infects wheat, rye, and various other grasses. T. caries is economically and agriculturally important because it reduces both the wheat yield and grain quality.
Urocystis agropyri is a fungal plant pathogen that causes flag smut on wheat.
Ustilago avenae is a plant pathogen. Semiloose smut of oats can be found wherever oats are grown, as they are seldom treated with seed treatments. The level of treatment is low because oats command a lower sale price than other cereals and hence it is thought that treatment is uneconomic. Semiloose smut of oats, unlike loose smut of wheat and barley, can thus infect up to 80 per cent of a crop.
Ustilaginoidea virens, perfect sexual stage Villosiclava virens, is a plant pathogen which causes the disease "false smut" of rice which reduces both grain yield and grain quality. The disease occurs in more than 40 countries, especially in the rice producing countries of Asia. but also in the U.S. As the common name suggests, it is not a true smut (fungus), but an ascomycete. False smut does not replace all or part of the kernel with a mass of black spores, rather sori form erupting through the palea and lemma forming a ball of mycelia, the outermost layers are spore-producing. Infected rice kernels are always destroyed by the disease.
Sporisorium reilianum Langdon & Full., (1978), previously known as Sphacelotheca reiliana, and Sporisorium reilianum, is a species of biotrophic fungus in the family Ustilaginaceae. It is a plant pathogen that infects maize and sorghum.
Tilletia barclayana is a plant pathogen that infects rice, signalgrass, pearl millet, and crabgrass. The pathogen corrupts the crops it infects, causing black busts to appear on the crops, which then become discolored and smutted.
Tilletia is a genus of smut fungi in the Tilletiaceae family. Species in this genus are plant pathogens that affect various grasses. Tilletia indica, which causes Karnal bunt of wheat, and Tilletia horrida, responsible for rice kernel smut, are examples of species that affect economically important crops.
Salmacisia is a fungal genus in the family Tilletiaceae. It is a monotypic genus, containing the single species Salmacisia buchloëana, first described as Tilletia buchloëana in 1889, and renamed in 2008. Plants infected by the fungus undergo a phenomenon known as "parasitically induced hermaphroditism", whereby ovary development is induced in otherwise male plants. Because of the pistil-inducing effects of the fungus, the authors have named the species pistil smut; it is the only species in the order Tilletiales known to have hermaphroditic effects.
Bacterial leaf streak (BLS), also known as black chaff, is a common bacterial disease of wheat. The disease is caused by the bacterial species Xanthomonas translucens pv. undulosa. The pathogen is found globally, but is a primary problem in the US in the lower mid-south and can reduce yields by up to 40 percent.[6] BLS is primarily seed-borne and survives in and on the seed, but may also survive in crop residue in the soil in the off-season. During the growing season, the bacteria may transfer from plant to plant by contact, but it is primarily spread by rain, wind and insect contact. The bacteria thrives in moist environments, and produces a cream to yellow bacterial ooze, which, when dry, appears light colored and scale-like, resulting in a streak on the leaves. The invasion of the head of wheat causes bands of necrotic tissue on the awns, which is called Black Chaff.[14] The disease is not easily managed, as there are no pesticides on the market for treatment of the infection. There are some resistant cultivars available, but no seed treatment exists. Some integrated pest management (IPM) techniques may be used to assist with preventing infection although, none will completely prevent the disease.[2]
References
- ↑ Takahashi Y (1896). "On Ustilago virens Cooke and a new species of Tilletia parasitic on rice-plant". Botany Magazine (Shokubutsugaku Zasshi). 10 (109): 16–20 + Plates I–II. doi: 10.15281/jplantres1887.10.109_16 . eISSN 0006-808X. ISSN 2185-3835. OCLC 26287357.
- Carris, Lori M.; Castlebury, Lisa A.; Goates, Blair J. (2006). "Nonsystemic Bunt Fungi—Tilletia indica and T. horrida: A Review of History, Systematics, and Biology". Annual Review of Phytopathology . Annual Reviews. 44 (1): 113–133. doi:10.1146/annurev.phyto.44.070505.143402. ISSN 0066-4286.
- 1 2 p. 115, "...described as or transferred to Neovossia (41), including ... T. horrida[as Neovossia horrida (Takah.) Padwick & A. Khan]. The distinction between Neovossia and Tilletia has been controversial."
- ↑ p. 125, "Under natural conditions, T. horrida has been reported only from rice (Oryza L.), but erroneous reports in the literature have led to considerable confusion over its host range and biology."
- 1 2 p. 126, "In tests of 32 species of grasses, T. horrida infected only rice and, surprisingly, the wheat relative Aegilops sharonensis (106). Whitney (143) showed in other tests that T. horrida infected rice, but not Pennisetum, and that seedling inoculations did not result in infection."
- ↑ p. 117, "Rice Kernel Smut—Tilletia horrida Rice kernel smut, also known as caryopsis smut, black smut, or grain smut (11), is caused by the pathogen T. horrida (Figure 5), which ... causes a partial bunt that affects both yield and quality."
- ↑ p. 126, "Tullis & Johnson (134) synonymized T. horrida with Tilletia barclayana (Bref.) Sacc. & Syd. based on questionable results of a study in which seedlings of two species of Pennisetum L.C. Rich. were artificially infected with the rice pathogen. Although the rice plants were not infected and the resulting teliospores from the inoculated species of Pennisetum were morphologically more similar to T. barclayana than to T. horrida, this was considered proof of synonymy (134). ... However, the synonymy of T. horrida with T. barclayana prevailed until molecular data proved the species were genetically distinct (25, 98).
- ↑ p. 117, "Teliospores can range from 20 to 38𝜇m in diameter."
- ↑ p. 119, "Postharvest dormancy of teliospores also occurs in T. horrida (28). Even after teliospores are stored more than one year, germination rarely exceeds 50% under optimal laboratory conditions and is 15%—30% in most reports. This demonstrates the second type of dormancy, which is long-term and likely contributes to teliospore survival under field conditions."
- ↑ p. 117, "...By the early 1900s, rice smut was considered widespread in eastern and southern Asia and had been reported in India, Java, Siam, and China (102). Anderson (1) discovered the disease in the United States in 1898 in rice plants from Georgetown, South Carolina, but misidentified the pathogen as Tilletia corona Scrib. He reported that the introduction of rice smut into South Carolina was via Japanese rice seed (2). Reyes (102) was the first to observe rice smut in the Philippines in 1920, apparently introduced on rice seed."
- 1 2 p. 117, "Rice kernel smut is considered a persistent but minor disease throughout rice-growing regions of the world (11, 26, 91)."
- ↑ p. 117, "Today, rice kernel smut occurs throughout Asia, Australasia and Oceania, in Europe (Greece), Central America (Belize, Cuba, Nicaragua, Panama, and Trinidad), South America (Brazil, Guyana, Surinam, Venezuela), North America (Mexico, United States), and Sierra Leone in Africa (31, 142). A specimen from Senegal, West Africa in Herb. BPI (41) on "Oryza sp." suggests the pathogen may be more widespread in Africa than is indicated in current distribution maps. In the United States, rice kernel smut occurs throughout rice-growing regions in Arkansas, California, Louisiana, Mississippi, South Carolina, and Texas (31, 141). In general, it is more severe in Arkansas, Mississippi, and Missouri than in other U.S. rice-growing regions (56)."
- ↑ p. 117, "In general, long-grain rice cultivars, the predominant type grown in the United States, are most susceptible to T. horrida, with short-grain rice the least susceptible, and medium-grain rice intermediate in susceptibility (11). Rice containing more than 3% bunted kernels is graded "smutty" (135) and is penalized at the mill (56)."
- 1 2 p. 117, "Disease incidence as high as 87% and 100% in hybrid rice seed production fields have been reported in Pakistan and China, respectively, although average infection rates in "normal" years are generally less than 25% (11). Even a low incidence of infection can cause substantial economic losses in hybrid rice seed production because a maximum of 0.5% infection is allowed in certified seed in India (11)."
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