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Pythiaceae
Pythiaceae is a family of water moulds. The family includes serious plant and animal pathogens in the genus ''Pythium''. The family was circumscribed by German mycologist Joseph Schröter in 1893. Lifecycle *Live on land (terrestrial), and in water ( aquatic), and a combination of the two, (amphibious) *Live as deadly parasites, causing some serious plant and animal diseases when terrestrial. *The diploid (2N) life stage predominates, with a short haplophase initiated during sexual reproduction as well as asexual reproduction (homothallism predominates in the Family) to fuse gametes. Reproduction The sporangia may germinate via a germ tube or by release of motile zoospores, depending on the species and the environmental conditions. Economic importance Some ''Pythium'' species cause "damping off Damping off (or damping-off) is a horticultural disease or condition, caused by several different pathogens that kill or weaken seeds or seedlings before or after they germinate. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Mould
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 pathogens. O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pythium
''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'' and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peronosporales
The Peronosporales are an order 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 ''Peronospora hyoscyami'' f.sp. ''tabacina'' is a plant pathogen infecting tobacco that causes blue mold. It is an oomycete (a fungus-like organism) that is highly destructive toward seed plants. It is very prevalent in humid farming zones, .... 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] |
Phytophthora
''Phytophthora'' (from Greek language, 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 degradation, 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 Anton de Bary, Heinrich Anton de Bary in 1875. Approximately 170 species have been described, although 100–500 undiscovered ''Phytophthora'' species are estimated to exist. Pathogenicity ''Phytophthora'' species, 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, coni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquatic Ecosystem
An aquatic ecosystem is an ecosystem formed by surrounding a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms that are dependent on each other and on their environment. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Freshwater ecosystems may be lentic (slow moving water, including pools, ponds, and lakes); lotic (faster moving water, for example streams and rivers); and wetlands (areas where the soil is saturated or inundated for at least part of the time). Types Marine ecosystems Marine coastal ecosystem Marine surface ecosystem Freshwater ecosystems Lentic ecosystem (lakes) Lotic ecosystem (rivers) Wetlands Functions Aquatic ecosystems perform many important environmental functions. For example, they recycle nutrients, purify water, attenuate floods, recharge ground water and provide habitats for wildlife. Aquatic ecosystems are also used for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Damping Off
Damping off (or damping-off) is a horticultural disease or condition, caused by several different pathogens that kill or weaken seeds or seedlings before or after they germinate. It is most prevalent in wet and cool conditions. Symptoms There are various symptoms associated with damping off; these reflect the variety of different pathogenic organisms which can cause the condition. However, all symptoms result in the death of at least some seedlings in any given population.Buczacki, S., and Harris, K., ''Pests, Diseases and Disorders of Garden Plants'', Collins, 1998, pp. 481–2. Groups of seedlings may die in roughly circular patches, the seedlings sometimes having stem lesions at ground level. Stems of seedlings may also become thin and tough ("wire-stem") resulting in reduced seedling vigor. Leaf spotting sometimes accompanies other symptoms, as does a grey mold growth on stems and leaves. Roots sometimes rot completely or back to just discolored stumps. Causal agents A numbe ... [...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 types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germ Tube
A germ tube is an outgrowth produced by spores of spore-releasing fungi during germination. The germ tube differentiates, grows, and develops by mitosis to create somatic hyphae.C.J. Alexopolous, Charles W. Mims, M. Blackwell, ''Introductory Mycology, 4th ed.'' (John Wiley and Sons, Hoboken NJ, 2004) A germ tube test is a diagnostic test in which a sample of fungal spores are suspended in animal serum and examined by microscopy for the detection of any germ tubes.Chapter IV. Germ Tube Test iYEAST IDENTIFICATION document at doctorfungus.org. Retrieved July 2011 It is particularly indicated for colonies of white or cream color on fungal culture, where a positive germ tube test is strongly indicative of ''Candida albicans''. See also * Oomycota 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporangia
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in nearly all land plants and many fungi, sporangia are the site of meiosis and produce genetically distinct haploid spores. Fungi In some phyla of fungi, the sporangium plays a role in asexual reproduction, and may play an indirect role in sexual reproduction. The sporangium forms on the sporangiophore and contains haploid nuclei and cytoplasm. Spores are formed in the sporangiophore by encasing each haploid nucleus and cytoplasm in a tough outer membrane. During asexual reproduction, these spores are dispersed via wind and germinate into haploid hyphae. Although sexual reproduction in fungi varies between phyla, for some fungi the sporangium plays an indirect role in sexual reproducti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamete
A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete—called an ovum— and a male produces the smaller type—called a sperm. Sperm cells or spermatozoa are small and motile due to the flagellum, a tail-shaped structure that allows the cell to propel and move. In contrast, each egg cell or ovum is relatively large and non-motile. In short a gamete is an egg cell (female gamete) or a sperm (male gamete). In animals, ova mature in the ovaries of females and sperm develop in the testes of males. During fertilization, a spermatozoon and ovum unite to form a new diploid organism. Gametes carry half the genetic information of an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homothallism
Homothallic refers to the possession, within a single organism, of the resources to reproduce sexually; i.e., having male and female reproductive structures on the same thallus. The opposite sexual functions are performed by different cells of a single mycelium. It can be contrasted to heterothallic. It is often used to categorize fungi. In yeast, heterothallic cells have mating types a and α. An experienced mother cell (one that has divided at least once) will switch mating type every cell division cycle because of the ''HO'' allele. Sexual reproduction commonly occurs in two fundamentally different ways in fungi. These are outcrossing (in heterothallic fungi) in which two different individuals contribute nuclei to form a zygote, and self-fertilization or selfing (in homothallic fungi) in which both nuclei are derived from the same individual. Homothallism in fungi can be defined as the capability of an individual spore to produce a sexually reproducing colony when propagated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asexual Reproduction
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the newly created individual is genetically and physically similar to the parent or an exact clone of the parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and eubacteria, bacteria. Many Eukaryote, eukaryotic organisms including plants, animals, and Fungus, fungi can also reproduce asexually. In vertebrates, the most common form of asexual reproduction is parthenogenesis, which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited. Komodo dragons and some monitor lizards can also reproduce asexually. While all prokaryotes reproduce without the formation and fusion of gametes, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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