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Powdery Mildew (barley)
Powdery mildew is a fungal disease of barley caused by ''Blumeria graminis'' f. sp. ''hordei''. The disease has a worldwide distribution and is most damaging in cool, wet climates. The host range of the form species ''hordei'' is restricted to barley and other '' Hordeum species''. Symptoms At first, powdery mildew can be observed as small greyish patches of fluffy fungal growth (mycelium) on the upper surface of the lower leaves. These spots resemble small cushions of white powder. Leaf tissue on the opposite side of an infected leaf turns pale green to yellow. The fungus only infects the epidermal layer and can be easily scraped off with a fingernail. Infections can also occur on the leaf sheaths and ears. Leaves remain green and active for some time following infection, then gradually become chlorotic and die off. As the disease progresses, the mycelium often becomes dotted with minute black points (cleistothecia), which are the sexual fruiting bodies of the fungus. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blumeria Graminis
''Blumeria graminis'' (commonly called barley powdery mildew or corn mildew) is a fungus that causes powdery mildew on grasses, including cereals. It is the only species in the genus ''Blumeria''. It has also been called ''Erysiphe graminis'' and (by its anamorph) ''Oidium monilioides'' or ''Oidium tritici''. Systematics Previously ''B. graminis'' was included within the genus ''Erysiphe'', but molecular studies have placed it into a clade of its own. Thus since 1975, the species ''graminis'' was moved into the new taxa ''Blumeria'' of which it is the only species. ''Blumeria'' differs from ''Erysiphe'' in its digitate haustoria and in details of the conidial wall. As well ''Blumeria'' is considered to be phylogenetically distinct from ''Erisiphe'' as it is a plant pathogen that hosts solely on the true grasses of ''Poaceae. '' Eight special forms or ''formae speciales'' (ff.spp.) of ''B. graminis'' have been distinguished, each of which is parasitic on a particular genus of gras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fungus
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from the other eukaryotic kingdoms, which by one traditional classification include Plantae, Animalia, Protozoa, and Chromista. A characteristic that places fungi in a different kingdom from plants, bacteria, and some protists is chitin in their cell walls. Fungi, like animals, are heterotrophs; they acquire their food by absorbing dissolved molecules, typically by secreting digestive enzymes into their environment. Fungi do not photosynthesize. Growth is their means of mobility, except for spores (a few of which are flagellated), which may travel through the air or water. Fungi are the principal decomposers in ecological systems. These and other differences place fungi in a single group of related organisms, named the ''Eumycota'' (''true f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley production is used as animal fodder, while 30% as a source of fermentable material for beer and certain distilled beverages, and as a component of various foods. It is used in soups and stews, and in barley bread of various cultures. Barley grains are commonly made into malt in a traditional and ancient method of preparation. In 2017, barley was ranked fourth among grains in quantity produced () behind maize, rice and wheat. Etymology The Old English word for barley was ', which traces back to Proto-Indo-European and is cognate to the Latin word ' "flour" (''see corresponding entries''). The direct ancestor of modern English ''barley'' in Old English was the derived adjective ''bærlic'', meaning "of barley". The first citation of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hordeum
''Hordeum'' is a genus of annual and perennial plants in the grass family. They are native throughout the temperate regions of Africa, Eurasia, and the Americas. One species, ''Hordeum vulgare'' (barley), has become of major commercial importance as a cereal grain, used as fodder crop and for malting in the production of beer and whiskey. Some species are nuisance weeds introduced worldwide by human activities, others have become endangered due to habitat loss. ''Hordeum'' species are used as food plants by the larvae of some Lepidoptera species, including the flame, rustic shoulder-knot and setaceous Hebrew character. The name '' Hordeum'' comes from the Latin word for "to bristle" (''horreō'', ''horrēre''), and is akin to the word " horror". Species Species include: * '' Hordeum aegiceras'' – Mongolia, China including Tibet * ''Hordeum arizonicum'' US (CA AZ NV NM), Mexico (Baja California, Sonora, Durango) * '' Hordeum bogdanii'' – from Turkey and European Ru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mildew
Mildew is a form of fungus. It is distinguished from its closely related counterpart, mould, largely by its colour: moulds appear in shades of black, blue, red, and green, whereas mildew is white. It appears as a thin, superficial growth consisting of minute hyphae (fungal filaments) produced especially on living plants or organic matter such as wood, paper or leather. Both mould and mildew produce distinct offensive odours, and both have been identified as the cause of certain human ailments. In horticulture, mildew is either species of fungus in the order Erysiphales, or fungus-like organisms in the family ''Peronosporaceae''. It is also used more generally to mean mould growth. In Old English, mildew meant honeydew (a substance secreted by aphids on leaves, formerly thought to distill from the air like dew), and later came to mean mould or fungus. Mildew grows on damp cloth, leather, or on plants, and growing on leaves can damage the plant. Household varieties The term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mycelium
Mycelium (plural mycelia) 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 substrate (biology), substrates. A typical single spore germinates into a Monokaryon, monokaryotic mycelium, which cannot reproduce sexually; when two compatible monokaryotic mycelia join and form a dikaryotic mycelium, that mycelium may form sporocarp (fungi), 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''. Through the mycelium, a fungus absorbs nutrients from its environment. It does this in a two-stage process. First, the hyphae secrete enzymes onto or into the food source, which break down biopolymers, biological polymers into smaller units such as monomers. These monomers are then absorbed into the mycelium by facilitated diffusion and active transport. Mycelia are v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorosis
In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to manufacture carbohydrates through photosynthesis and may die unless the cause of its chlorophyll insufficiency is treated and this may lead to a plant diseases called rusts, although some chlorotic plants, such as the albino ''Arabidopsis thaliana'' mutant ''ppi2'', are viable if supplied with exogenous sucrose. The word ''chlorosis'' is derived from the Greek ''khloros'' meaning "greenish-yellow", "pale green", "pale", "pallid", or "fresh". In viticulture, the most common symptom of poor nutrition in grapevines is the yellowing of grape leaves caused by chlorosis and the subsequent loss of chlorophyll. This is often seen in vineyard soils that are high in limestone such as the Italian wine region of Barolo in the Piedmont, the Spanish wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cleistothecia
An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are most commonly bowl-shaped (apothecia) but may take on a spherical or flask-like form that has a pore opening to release spores (perithecia) or no opening (cleistothecia). Classification The ascocarp is classified according to its placement (in ways not fundamental to the basic taxonomy). It is called ''epigeous'' if it grows above ground, as with the morels, while underground ascocarps, such as truffles, are termed ''hypogeous''. The structure enclosing the hymenium is divided into the types described below (apothecium, cleistothecium, etc.) and this character ''is'' important for the taxonomic classification of the fungus. Apothecia can be relatively large and fleshy, whereas the others are microscopic—about the size of flecks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conidium
A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the way they are generated through the cellular process of mitosis. The two new haploid cells are genetically identical to the haploid parent, and can develop into new organisms if conditions are favorable, and serve in biological dispersal. Asexual reproduction in ascomycetes (the phylum Ascomycota) is by the formation of conidia, which are borne on specialized stalks called conidiophores. The morphology of these specialized conidiophores is often distinctive between species and, before the development of molecular techniques at the end of the 20th century, was widely used for identification of (''e.g.'' ''Metarhizium'') species. The terms microconidia and macroconidia are sometimes used. Conidiogenesis There are two main types of co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ascospore
An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or species can occur in numbers of one (e.g. ''Monosporascus cannonballus''), two, four, or multiples of four. In a few cases, the ascospores can bud off conidia that may fill the asci (e.g. ''Tympanis'') with hundreds of conidia, or the ascospores may fragment, e.g. some ''Cordyceps'', also filling the asci with smaller cells. Ascospores are nonmotile, usually single celled, but not infrequently may be coenocytic (lacking a septum), and in some cases coenocytic in multiple planes. Mitotic divisions within the developing spores populate each resulting cell in septate ascospores with nuclei. The term ocular chamber, or oculus, refers to the epiplasm (the portion of cytoplasm not used in ascospore formation) that is surrounded by the "bourrelet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propagule
In biology, a propagule is any material that functions in propagating an organism to the next stage in its life cycle, such as by dispersal. The propagule is usually distinct in form from the parent organism. Propagules are produced by organisms such as plants (in the form of seeds or spores), fungi (in the form of spores), and bacteria (for example endospores or microbial cysts). In disease biology, pathogens are said to generate infectious propagules, the units that transmit a disease. These can refer to bacteria, viruses, fungi, or protists, and can be contained within host material. For instance, for influenza, the infectious propagules are carried in droplets of host saliva or mucus that are expelled during coughing or sneezing. In horticulture, a propagule is any plant material used for the purpose of plant propagation. In asexual reproduction, a propagule is often a stem cutting. In some plants, a leaf section or a portion of root can be used. In sexual reproduction, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporulation
In biology, a spore is a unit of sexual 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 plants, algae, fungi and protozoa. Bacterial spores are not part of a sexual cycle, but are resistant structures used for survival under unfavourable conditions. Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection, but also reproduce within the hosts through the pairing of two nuclei within the plasmodium, which develops from the amoebula. In plants, spores are usually haploid and unicellular and are produced by meiosis in the sporangium of a diploid sporophyte. Under favourable conditions the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes. Two gametes fuse to form a zygote which develops into a new sporo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
