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Pythium Polare
''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequently a vector for their transmission. Morphology ;Hyphae: ''Pythium'' species, like others in the family Pythiaceae, are usually characterized by their production of coenocytic hyphae without septations. ;Oogonia: Generally contain a single oospore. ;Antheridia: Contain an elongated and club-shaped antheridium. Ecological importance ''Pythium''-induced root rot is a common crop disease. When the organism kills newly emerged or emerging seedlings, it is known as damping off, and is a very common problem in fields and greenhouses. Thus there is tremendous interest in genetic host resistance, but no crop has ever developed adequate resistance to ''Pythium''. This disease complex usually involves other pathogens such as ''Phytophthora'' a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase-contrast Microscopy
__NOTOC__ Phase-contrast microscopy (PCM) is an optical microscopy technique that converts phase shifts in light passing through a transparent specimen to brightness changes in the image. Phase shifts themselves are invisible, but become visible when shown as brightness variations. When light waves travel through a medium other than a vacuum, interaction with the medium causes the wave amplitude and phase to change in a manner dependent on properties of the medium. Changes in amplitude (brightness) arise from the scattering and absorption of light, which is often wavelength-dependent and may give rise to colors. Photographic equipment and the human eye are only sensitive to amplitude variations. Without special arrangements, phase changes are therefore invisible. Yet, phase changes often convey important information. Phase-contrast microscopy is particularly important in biology. It reveals many cellular structures that are invisible with a bright-field microscope, as exemp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antheridium
An antheridium is a haploid structure or organ producing and containing male gametes (called ''antherozoids'' or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. Androecium is also the collective term for the stamens of flowering plants. Antheridia are present in the gametophyte phase of cryptogams like bryophytes and ferns. Many algae and some fungi, for example ascomycetes and water moulds, also have antheridia during their reproductive stages. In gymnosperms and angiosperms, the male gametophytes have been reduced to pollen grains and in most of these the antheridia have been reduced to a single generative cell within the pollen grain. During pollination, this generative cell divides and gives rise to sperm cells. The female counterpart to the antheridium in cryptogams is the archegonium, and in flowering plants is the gynoecium. An antheridium typically consists of sterile cells and spermatogenous ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Pathology
Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants. Not included are ectoparasites like insects, mites, vertebrate, or other pests that affect plant health by eating plant tissues. Plant pathology also involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology, plant disease resistance, how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases. Overview Control of plant diseases is crucial to the reliable production of food, and it provides significant problems in agricultural use of land, water, fuel and other inputs. Plants in both natural and cultivated popu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Pretoria
The University of Pretoria ( af, Universiteit van Pretoria, nso, Yunibesithi ya Pretoria) is a multi-campus public research university in Pretoria, the administrative and de facto capital of South Africa. The university was established in 1908 as the Pretoria campus of the Johannesburg-based Transvaal University College and is the fourth South African institution in continuous operation to be awarded university status. The university has grown from the original 32 students in a single late Victorian house to approximately 53,000 in 2019. The university was built on seven suburban campuses on . The university is organised into nine faculties and a business school. Established in 1920, the University of Pretoria Faculty of Veterinary Science is the second oldest veterinary school in Africa and the only veterinary school in South Africa. In 1949, the university launched the first MBA programme outside North America, and the university's Gordon Institute of Business Science (GIBS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Guelph
, mottoeng = "to learn the reasons of realities" , established = May 8, 1964 ()As constituents: OAC: (1874) Macdonald Institute: (1903) OVC: (1922) , type = Public university , chancellor = Mary Anne Chambers (not yet installed) , president = Charlotte A.B. Yates , city = Guelph, Ontario , country = Canada , students = 29,923 , undergrad = 23,926 , postgrad = 3,035 , faculty = 830 , administrative_staff = 3,100 , campus = Urban , athletics_affiliations = CIS, OUA , sports_nickname = Gryphons , colours = , , affiliations = AUCC, CARL, IAU, COU, CIS, CUSID, Fields Institute, OUA, Ontario Network of Women in engineering, CBIE , endowment = CA$418 million (2021) , website = , logo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or more distinct types of flagella - tinsel or "decorated", and whiplash, in various combinations. *Tinsellated (straminipilous) flagella have lateral filaments known as mastigonemes perpendicular to their main axis, which allow for more surface area, and disturbance of the medium, giving them the property of a rudder, that is, used for steering. *Whiplash flagella are straight, to power the zoospore through its medium. Also, the "default" zoospore only has the propelling, whiplash flagella. Both tinsel and whiplash flagella beat in a sinusoidal wave pattern, but when both are present, the tinsel beats in the opposite direction of the whiplash, to give two axes of control of motility. Morphological types In eukaryotes, the four main ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizoctonia Solani
''Rhizoctonia solani'' is a species of fungus in the order Cantharellales. Basidiocarps (fruit bodies) are thin, effused, and web-like, but the fungus is more typically encountered in its anamorphic state, as hyphae and sclerotia. The name ''Rhizoctonia solani'' is currently applied to a complex of related species that await further research. In its wide sense, ''Rhizoctonia solani'' is a facultative plant pathogen with a wide host range and worldwide distribution. It causes various plant diseases such as root rot, damping off, and wire stem. It can also form mycorrhizal associations with orchids. Taxonomy In 1858, the German plant pathologist Julius Kühn observed and described a fungus on diseased potato tubers and named it ''Rhizoctonia solani'', the species epithet referring to '' Solanum tuberosum'' (potato). The disease caused was well known before the discovery and description of the fungus. In 1956, Dutch mycologist M.A. Donk published the new name ''Thanatephorus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytophthora
''Phytophthora'' (from Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species are capable of causing enormous economic losses on crops worldwide, as well as environmental damage in natural ecosystems. As well as impacting large scale agriculture, ''Phytophthora'' is a nuisance to garden and indoor plant hobbyists as well as bonsai artists. The cell wall of ''Phytophthora'' is made up of cellulose. The genus was first described by Heinrich Anton de Bary in 1875. Approximately 170 species have been described, although 100–500 undiscovered ''Phytophthora'' species are estimated to exist. Pathogenicity ''Phytophthora'' spp. are mostly pathogens of dicotyledons, and many are relatively host-specific parasites. ''Phytophthora cinnamomi'', though, infects thousands of species ranging from club mosses, ferns, cycads, conifers, grasses, lilies, to members of many dicotyledonous famil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Summa Phytopathologica
Summa and its diminutive summula (plural ''summae'' and ''summulae'', respectively) was a medieval didactics literary genre written in Latin, born during the 12th century, and popularized in 13th century Europe. In its simplest sense, they might be considered texts that 'sum up' knowledge in a field, such as the compendiums of theology, philosophy and canon law. Their function during the Middle Ages was largely as manuals or handbooks of necessary knowledge used by individuals who would not advance their studies any further. Features It was a kind of encyclopedia that developed a matter about Law, Theology or Philosophy most of all. Matters were divided in a more detailed way as it was in the ''tractatus'' (treatise), since they were divided into ''quaestiones'' (questions) and these ones were also divided into ''articles''. The articles had the following structure: #Title of the article as a question and showing two different positions (''disputatio''). #Objections or arguments a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Disease Resistance
Plant disease resistance protects plants from pathogens in two ways: by pre-formed structures and chemicals, and by infection-induced responses of the immune system. Relative to a susceptible plant, disease resistance is the reduction of pathogen growth on or in the plant (and hence a reduction of disease), while the term disease tolerance describes plants that exhibit little disease damage despite substantial pathogen levels. Disease outcome is determined by the three-way interaction of the pathogen, the plant and the environmental conditions (an interaction known as the disease triangle). Defense-activating compounds can move cell-to-cell and systematically through the plant's vascular system. However, plants do not have circulating immune cells, so most cell types exhibit a broad suite of antimicrobial defenses. Although obvious ''qualitative'' differences in disease resistance can be observed when multiple specimens are compared (allowing classification as “resistant” or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breeding For Resistance
Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as breeds, normally bred by a professional breeder, while domesticated plants are known as varieties, cultigens, cultivars, or breeds. Two purebred animals of different breeds produce a crossbreed, and crossbred plants are called hybrids. Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually the provenance of the professionals. In animal breeding, techniques such as inbreeding, linebreeding, and outcrossing are utilized. In plant breeding, similar methods are used. Charles Darwin discussed how selective breeding had been successful in producing change over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saint Paul, Minnesota
Saint Paul (abbreviated St. Paul) is the capital of the U.S. state of Minnesota and the county seat of Ramsey County. Situated on high bluffs overlooking a bend in the Mississippi River, Saint Paul is a regional business hub and the center of Minnesota's government. The Minnesota State Capitol and the state government offices all sit on a hill close to the city's downtown district. One of the oldest cities in Minnesota, Saint Paul has several historic neighborhoods and landmarks, such as the Summit Avenue Neighborhood, the James J. Hill House, and the Cathedral of Saint Paul. Like the adjacent and larger city of Minneapolis, Saint Paul is known for its cold, snowy winters and humid summers. As of the 2021 census estimates, the city's population was 307,193, making it the 67th-largest city in the United States, the 12th-most populous in the Midwest, and the second-most populous in Minnesota. Most of the city lies east of the Mississippi River near its confluence with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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