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Peronospora Parasitica
''Hyaloperonospora parasitica'' is an oomycete from the family Peronosporaceae. It has been considered for a long time to cause downy mildew of a variety of species within the Brassicaceae, on which the disease can cause economically important damage by killing seedlings or affecting the quality of produce intended for freezing. ''Hyaloperonospora parasitica''http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=39723 causes downy mildew on a wide range of many different plants. It belongs to the Kingdom Chromista, the phylum Oomycota, and the family Peronosporaceae. The former name for ''H. parasitica'' was ''Peronospora parasitica'' until it was reclassified and put in the genus Hyaloperonospora. It is an especially vicious disease on crops of the family Brassicaceae. It is most famous for being a model pathogen of ''Arabidopsis thaliana'' which is a model organism used for experimental purposes. Accordingly, the former ''Hyaloperonospora'' parasitica has been split into a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyaloperonospora Arabidopsidis
''Hyaloperonospora arabidopsidis'' is a species from the family Peronosporaceae. It is an obligate parasite and the causal agent of the downy mildew of the plant model organism ''Arabidopsis thaliana''. While ''H. arabidopsidis'' has for a long time been subsumed under ''Peronospora parasitica'' (now ''Hyaloperonospora parasitica''), recent studies have shown that ''H. parasitica'' is restricted to ''Capsella bursa-pastoris'' as a host plant. Like the other ''Hyaloperonospora'' species, ''H. arabidopsidis'' is highly specialized to ''Arabidopsis thaliana''. References * Further reading Peronosporales Water mould plant pathogens and diseases Eudicot diseases Arabidopsis thaliana {{plant-disease-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabidopsis Thaliana
''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. ''A. thaliana'' is considered a weed; it is found along the shoulders of roads and in disturbed land. A winter annual with a relatively short lifecycle, ''A. thaliana'' is a popular model organism in plant biology and genetics. For a complex multicellular eukaryote, ''A. thaliana'' has a relatively small genome around 135 megabase pairs. It was the first plant to have its genome sequenced, and is a popular tool for understanding the molecular biology of many plant traits, including flower development and light sensing. Description ''Arabidopsis thaliana'' is an annual (rarely biennial) plant, usually growing to 20–25 cm tall. The leaves form a rosette at the base of the plant, with a few leaves also on the flowering stem. The basal leaves are green to slightly purplish in color, 1.5–5 cm long, and 2–10 mm broad, with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oomycete
Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the result of contact between hyphae of male antheridia and female oogonia; these spores can overwinter and are known as resting spores. Asexual reproduction involves the formation of chlamydospores and sporangia, producing motile zoospores. Oomycetes occupy both saprophytic and pathogenic lifestyles, and include some of the most notorious pathogens of plants, causing devastating diseases such as late blight of potato and sudden oak death. One oomycete, the mycoparasite '' Pythium oligandrum'', is used for biocontrol, attacking plant pathogenic fungi. The oomycetes are also often referred to as water molds (or water moulds), although the water-preferring nature which led to that name is not true of most species, which are terrestrial pathoge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peronosporaceae
Peronosporaceae are a family of water moulds that contains 21 genera, comprising more than 600 species. Most of them are called downy mildews. Peronosporaceae are obligate biotrophic plant pathogens. They parasitise their host plants as an intercellular mycelium using haustoria to penetrate the host cells. The downy mildews reproduce asexually by forming sporangia on distinctive white sporangiophores usually formed on the lower surface of infected leaves. These constitute the "downy mildew". The sporangia are wind-dispersed to the surface of other leaves. According to the genus concerned, the sporangia may then germinate by forming zoospores, thus resembling ''Phytophthora'', or by germ-tube. In the latter case, the sporangia behave as conidia and are often referred to as such. Sexual reproduction is via oospores. The parasitised plants are angiosperms or gymnosperms, and most Peronosporaceae are pathogens of herbaceous dicots. Some downy mildew genera have a more res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brassicaceae
Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leaves are simple (although are sometimes deeply incised), lack stipules, and appear alternately on stems or in rosettes. The inflorescences are terminal and lack bracts. The flowers have four free sepals, four free alternating petals, two shorter free stamens and four longer free stamens. The fruit has seeds in rows, divided by a thin wall (or septum). The family contains 372 genera and 4,060 accepted species. The largest genera are '' Draba'' (440 species), ''Erysimum'' (261 species), ''Lepidium'' (234 species), ''Cardamine'' (233 species), and ''Alyssum'' (207 species). The family contains the cruciferous vegetables, including species such as ''Brassica oleracea'' (cultivated as cabbage, kale, cauliflower, broccoli and collards), '' Br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brassica
''Brassica'' () is a genus of plants in the cabbage and mustard family ( Brassicaceae). The members of the genus are informally known as cruciferous vegetables, cabbages, or mustard plants. Crops from this genus are sometimes called ''cole crops''derived from the Latin ''caulis'', denoting the stem or stalk of a plant. The genus ''Brassica'' is known for its important agricultural and horticultural crops and also includes a number of weeds, both of wild taxa and escapees from cultivation. ''Brassica'' species and varieties commonly used for food include bok choy, broccoli, cauliflower, cabbage, choy sum, kohlrabi, napa cabbage, rutabaga, turnip and some seeds used in the production of canola oil and the condiment mustard. Over 30 wild species and hybrids are in cultivation, plus numerous cultivars and hybrids of cultivated origin. Most are seasonal plants ( annuals or biennials), but some are small shrubs. ''Brassica'' plants have been the subject of much scientific i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyaloperonospora Brassicae
''Hyaloperonospora brassicae'', in the family Peronosporaceae, is a plant pathogen. It causes downy mildew of species of ''Brassica'', ''Raphanus'', ''Sinapis'' and probably other genera within the ''Brassicaceae''. In the past, the cause of downy mildew in any plant in the family ''Brassicaceae'' was considered to be a single species ''Peronospora parasitica''. However, this has recently been shown to be a complex of species with narrower host ranges, now classified in the genus '' Hyaloperonospora'', for example '' Hyaloperonospora parasitica'' on the weed ''Capsella bursa-pastoris''. From the perspective of plant pathology, ''Hyaloperonospora brassicae'' is now the name of the most important pathogen in this complex, attacking the major agricultural and horticultural ''Brassica'' species. Other significant Brassicaceous hosts are attacked by different species in the complex, e.g. horseradish (''Armoracia rusticana'') by ''Hyaloperonospora cochleariae'', wallflower (''Erysimum c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conidiophores
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] |
Oogonium
An oogonium (plural oogonia) is a small diploid cell which, upon maturation, forms a primordial follicle in a female fetus or the female (haploid or diploid) gametangium of certain thallophytes. In the mammalian fetus Oogonia are formed in large numbers by mitosis early in fetal development from primordial germ cells. In humans they start to develop between weeks 4 and 8 and are present in the fetus between weeks 5 and 30. Structure Normal oogonia in human ovaries are spherical or ovoid in shape and are found amongst neighboring somatic cells and oocytes at different phases of development. Oogonia can be distinguished from neighboring somatic cells, under an electron microscope, by observing their nuclei. Oogonial nuclei contain randomly dispersed fibrillar and granular material whereas the somatic cells have a more condensed nucleus that creates a darker outline under the microscope. Oogonial nuclei also contain dense prominent nucleoli. The chromosomal material in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peronosporales
The Peronosporales are an order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ... of water moulds (class Oomycetes) which can be pathogenic. Many diseases of plants are sometimes classified under this order, but are sometimes considered members of order Pythiales. Some of these pathogenic protists include the organisms responsible for potato blight, eucalyptus dieback, sudden oak death, and blue mold. Further genetic studies may place these organisms more definitively in one order or another. References Heterokont orders {{plant-disease-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protists Described In 2002
A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exclusion of other eukaryotes means that protists do not form a natural group, or clade. Therefore, some protists may be more closely related to animals, plants, or fungi than they are to other protists. However, like the groups '' algae'', ''invertebrates'', and '' protozoans'', the biological category ''protist'' is used for convenience. Others classify any unicellular eukaryotic microorganism as a protist. The study of protists is termed protistology. History The classification of a third kingdom separate from animals and plants was first proposed by John Hogg in 1860 as the kingdom Protoctista; in 1866 Ernst Haeckel also proposed a third kingdom Protista as "the kingdom of primitive forms". Originally these also included prokaryotes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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