Sclerotinia borealis | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Fungi |
Division: | Ascomycota |
Class: | Leotiomycetes |
Order: | Helotiales |
Family: | Sclerotiniaceae |
Genus: | Sclerotinia |
Species: | S. borealis |
Binomial name | |
Sclerotinia borealis Bubák & Vleugel, (1917) | |
Synonyms | |
Myriosclerotinia borealis [1] (Bubák & Vleugel) L.M. Kohn, (1979) Contents |
Sclerotinia borealis or snow scald is a psychrophilic necrotrophic plant pathogen with wide host range, including crop plants, such as barley, rye and wheat, and thus causing much economical damage. [2]
Minimum growth temperature is below −7 °C (19 °F). Optimal growth range is 10–15 °C (50–59 °F). Maximum growth temperature 20 °C (68 °F), whereupon irregular mycelial growth occurs and oxygen consumption is far above healthy level; does not survive above. Sclerotia germination optimal at four weeks of daily thermal cycles of 25 and 15 °C (77 and 59 °F) followed by 20 and 5 °C (68 and 41 °F). Frost is necessary during life cycle. [1]
Produces polygalacturonase; variant with maximum activity between 40 and 50 °C (104 and 122 °F) and only 30% of max activity at 5 °C (41 °F). Activity preserved at 5 °C (41 °F) beyond two years, but inactivated by overnight at room temperature, or by 30 minutes of 50 °C (122 °F). A crude extract of cultured bran contained a particular low mass molecule which maintained activity at low temperature. [1]
Necessitated by its lifestyle, S. borealis produces its own antifreeze proteins. One of these is homologous to Atlantic winter flounder type I antifreeze protein. Extracellular presence of its AFPs is not necessary. [1]
Upon the spring snowmelt, wet leaves develop S. borealis growth. Sclerotia and mycelia grow on sheaths, crowns, surfaces, and interiors of leaves. It has dramatically more growth – and damage to its hosts – in growth seasons following winters with greater depth of soil freezing but less snow cover. S. borealis is very soil-frost-dependent. [1]
Sclerotia are 7–8 millimetres (35⁄128–5⁄16 in) long and 3–4 millimetres (15⁄128–5⁄32 in) wide when formed (i.e. before desiccation).
Apothecia cup-shaped pale yellow to pale brown, cup diameter 1–6 millimetres (5⁄128–15⁄64 in), stalks 1–20 millimetres (5⁄128–101⁄128 in) high.
Mycelia gray. [1]
Grasses and trees. Economically significant grasses include winter cereals and forages. Conifer seedlings in the Volga and Ural regions Russia. [1]
S. borealis is found in cool temperate areas, frigid zone areas and into the Arctic, including northern Japan, Russia (Siberia, middle course of Volga, Ural, Russian Far East [3] ), northern Scandinavia, and North America. Specifically including Arctic areas of Alaska, the Yukon, Greenland, Finnmark county in Norway, Finnish Lapland, Swedish Lapland, Svalbard. It was unexpectedly not found in the similar climate of Iceland. Southernmost limit is Iwate, northern Japan, the Altai Mountains in central Siberia, and possibly the Xinjiang Province of China. Not found in any temperate region which also receives snowfall, except Japan. [1]
Lab culture must simulate the freezing cycle of the natural range. Can grow on relatively low water potato dextrose agar if twice the normal PDA concentration, sucrose, KCl, and D-mannitol. Higher mycelial growth and lower optimal mycelial growth temp (to 4 °C (39 °F)) if increased intracellular osmosis. Able to utilize nutrients from partially thawed low-water PDA. Vegetative hyphae do not accumulate sclerotinial proteins when cultured at 5 °C (41 °F) but do at 10 and 25 °C (50 and 77 °F), and mycelial proteins cultured at 4 °C (39 °F) are decreased by switch to incubation at 25 °C (77 °F). These may be the/one of the reasons for irregular growth, progressing to lethality, at these higher temperatures. [1]
Mycelium is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates into a monokaryotic mycelium, which cannot reproduce sexually; when two compatible monokaryotic mycelia join and form a dikaryotic mycelium, that mycelium may form fruiting bodies such as mushrooms. A mycelium may be minute, forming a colony that is too small to see, or may grow to span thousands of acres as in Armillaria. The network of mycelium acts similar to human brains, in the way that mycelium is used to send electrical signals to the fruiting bodies of mushrooms. These electrical signals can be used to convey information or warn about incoming danger.
Finnmark is a county in the northern part of Norway.
Botrytis cinerea is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or "gray mold".
A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, with an optimum growth range from 20 to 45 °C. The optimum growth temperature for these organisms is 37°C. The term is mainly applied to microorganisms. Organisms that prefer extreme environments are known as extremophiles. Mesophiles have diverse classifications, belonging to two domains: Bacteria, Archaea, and to kingdom Fungi of domain Eucarya. Mesophiles belonging to the domain Bacteria can either be gram-positive or gram-negative. Oxygen requirements for mesophiles can be aerobic or anaerobic. There are three basic shapes of mesophiles: coccus, bacillus, and spiral.
Antifreeze proteins (AFPs) or ice structuring proteins refer to a class of polypeptides produced by certain animals, plants, fungi and bacteria that permit their survival in temperatures below the freezing point of water. AFPs bind to small ice crystals to inhibit the growth and recrystallization of ice that would otherwise be fatal. There is also increasing evidence that AFPs interact with mammalian cell membranes to protect them from cold damage. This work suggests the involvement of AFPs in cold acclimatization.
Psychrophiles or cryophiles are extremophilic organisms that are capable of growth and reproduction in low temperatures, ranging from −20 °C (−4 °F) to 20 °C (68 °F). They are found in places that are permanently cold, such as the polar regions and the deep sea. They can be contrasted with thermophiles, which are organisms that thrive at unusually high temperatures, and mesophiles at intermediate temperatures. Psychrophile is Greek for 'cold-loving', from Ancient Greek ψυχρός (psukhrós) 'cold, frozen'.
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.
Chlamydomonas nivalis, also referred to as Chloromonas typhlos, is a unicellular red-coloured photosynthetic green alga that is found in the snowfields of the alps and polar regions all over the world. They are one of the main algae responsible for causing the phenomenon of watermelon snow, where patches of snow appear red or pink. The first account of microbial communities that form red snow was made by Aristotle. Researchers have been active in studying this organism for over 100 years.
A sclerotium, is a compact mass of hardened fungal mycelium containing food reserves. One role of sclerotia is to survive environmental extremes. In some higher fungi such as ergot, sclerotia become detached and remain dormant until favorable growth conditions return. Sclerotia initially were mistaken for individual organisms and described as separate species until Louis René Tulasne proved in 1853 that sclerotia are only a stage in the life cycle of some fungi. Further investigation showed that this stage appears in many fungi belonging to many diverse groups. Sclerotia are important in the understanding of the life cycle and reproduction of fungi, as a food source, as medicine, and in agricultural blight management.
Coprinopsis psychromorbida or Cottony Snow Mold is a cause of snow mold. It is a basidiomycete, a psychrophile, and a plant pathogen.
Sclerotinia sclerotiorum is a plant pathogenic fungus and can cause a disease called white mold if conditions are conducive. S. sclerotiorum can also be known as cottony rot, watery soft rot, stem rot, drop, crown rot and blossom blight. A key characteristic of this pathogen is its ability to produce black resting structures known as sclerotia and white fuzzy growths of mycelium on the plant it infects. These sclerotia give rise to a fruiting body in the spring that produces spores in a sac which is why fungi in this class are called sac fungi (Ascomycota). This pathogen can occur on many continents and has a wide host range of plants. When S. sclerotiorum is onset in the field by favorable environmental conditions, losses can be great and control measures should be considered.
Typhula incarnata is a fungal plant pathogen in the family Typhulaceae.
Typhula ishikariensis is, along with Typhula incarnata, the causal agent of grey snow mould, an obligately parasitic plant pathogen that can destroy turfgrass when covered for a long period with snow. It is a particular problem on golf courses established in unsuitable areas. More importantly, it can also damage crops of winter wheat. The species was described as new to science in 1930 by Japanese mycologist Sanshi Imai. The varieties canadensis and ishikariensis were described in 1978. There is a wide variety within the species and not all authorities agree as to subspecies, or even whether it should be monophyletic.
Typhula is a genus of clavarioid fungi in the order Agaricales. Species of Typhula are saprotrophic, mostly decomposing leaves, twigs, and herbaceous material. Basidiocarps are club-shaped or narrowly cylindrical and are simple, often arising from sclerotia. A few species are facultative plant pathogens, causing a number of commercially important crop and turfgrass diseases.
Pseudogymnoascus destructans is a psychrophilic (cold-loving) fungus that causes white-nose syndrome (WNS), a fatal disease that has devastated bat populations in parts of the United States and Canada. Unlike species of Geomyces, P. destructans forms asymmetrically curved conidia. Pseudogymnoascus destructans grows very slowly on artificial media and cannot grow at temperatures above 20 °C. It can grow around 4 °C to 20 °C, which encompasses the temperatures found in winter bat hibernacula. Phylogenic evaluation has revealed this organism should be reclassified under the family Pseudeurotiaceae, changing its name to Pseudogymnoascus destructans.
Typhula blight is most commonly known as a turf disease, but can also be a problem with wheat. Typhula blight is caused by a Typhula fungus, either Typhula incarnata or T. ishikariensis. Typhula incarnata is the causal agent for gray snow mold and T. ishikariensis causes speckled snow mold. Snow molds are caused by cold tolerant fungi that require snow cover or prolonged periods of cold, wet conditions. Typhula blight is most notably found in the turf industry, affecting a wide range of turfgrasses. Upon the snow melt, gray circular patches of mycelium are found. These mycelia produce a survival structure called a sclerotia that survives the warm summer months. Typhula blight is commonly controlled with fungicide applications in the late fall and by other cultural practices. If unchecked, snow molds can cause severe turf loss.
Stromatinia cepivora is a fungus in the division Ascomycota. It is the teleomorph of Sclerotium cepivorum, the cause of white rot in onions, garlic, and leeks. The infective sclerotia remain viable in the soil for many years and are stimulated to germinate by the presence of a susceptible crop.
Rhodoferax is a genus of Betaproteobacteria belonging to the purple nonsulfur bacteria. Originally, Rhodoferax species were included in the genus Rhodocyclus as the Rhodocyclus gelatinous-like group. The genus Rhodoferax was first proposed in 1991 to accommodate the taxonomic and phylogenetic discrepancies arising from its inclusion in the genus Rhodocyclus. Rhodoferax currently comprises four described species: R. fermentans, R. antarcticus, R. ferrireducens, and R. saidenbachensis. R. ferrireducens, lacks the typical phototrophic character common to two other Rhodoferax species. This difference has led researchers to propose the creation of a new genus, Albidoferax, to accommodate this divergent species. The genus name was later corrected to Albidiferax. Based on geno- and phenotypical characteristics, A. ferrireducens was reclassified in the genus Rhodoferax in 2014. R. saidenbachensis, a second non-phototrophic species of the genus Rhodoferax was described by Kaden et al. in 2014.
Echigoshirayukidake, commonly called Basidiomycetes-X or BDM-X, is a sclerotium of Ceraceomyces tessulatus. It is classified as a basidiomycete because of its beak-shaped processes. It does not form basidia and only forms sclerotia when cultured. In these respects, BDM-X is distinguished from other basidiomycetes. BDM-X is cultured and consumed as an edible mushroom. The mushroom, Basidiomycetes-X (BDM-X), echigoshirayukidake was identified as Ceraceomyces tessulatus, a member of the family Amylocorticiaceae based on the molecular analysis of ITS region and D1/D2 regions of rDNA. Sequence similarity between the mushroom and Ceraceomyces tessulatus voucher KHL16429, Herb. O was 99% in ITS1 region and 99% in 26 or 28S rDNA D1/D2 regions respectively.
Mariannaea elegans an anamorphic fungus. It is mainly found on rotting wood and soil. M. elegans is not pathogenic to humans, animals, or plants.