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Rice Hoja Blanca Tenuivirus
''Rice hoja blanca tenuivirus'' (RHBV), meaning "white leaf rice virus", is a plant virus in the family ''Phenuiviridae.'' RHBV causes Hoja blanca disease (HBD), which affects the leaves of the rice plant ''Oryza sativa'', stunting the growth of the plant or killing it altogether. RHBV is carried by an insect vector, ''Tagosodes orizicolus'', a type of planthopper. The virus is found in South America, Mexico, throughout Central America, the Caribbean region, and the southern United States. In South America, the disease is endemic to Colombia, Venezuela, Ecuador, Peru, Suriname, French Guiana and Guyana. Virology Viral Classification RHBV is a single stranded, negative-sense RNA virus of the genus ''Tenuivirus'', derived from the Latin "''tenui"'', meaning thin or weak. This comes from the nature of ''Tenuiviruses'' to form thin, filamentous viral particles. Other viruses in the genus ''Tenuivirus'' include maize stripe virus (MSV), rice stripe virus (RSV), and rice grassy stu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898,Dimmock p. 4 more than 9,000 virus species have been described in detail of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles, or ''virions'', consisting of (i) the genetic material, i. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Glycoprotein
Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. Secreted extracellular proteins are often glycosylated. In proteins that have segments extending extracellularly, the extracellular segments are also often glycosylated. Glycoproteins are also often important integral membrane proteins, where they play a role in cell–cell interactions. It is important to distinguish endoplasmic reticulum-based glycosylation of the secretory system from reversible cytosolic-nuclear glycosylation. Glycoproteins of the cytosol and nucleus can be modified through the reversible addition of a single GlcNAc residue that is considered reciprocal to phosphorylation and the functions of these are likely to be an additional regulatory mechanism that controls phosphorylation-based signalling. In contrast, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cauca River
The Cauca River () is a river in Colombia that lies between the Occidental and Central cordilleras. From its headwaters in southwestern Colombia near the city of Popayán, it joins the Magdalena River near Magangue in Bolivar Department, and the combined river eventually flows out into the Caribbean Sea. It has a length of to its junction with the Magdalena, for a total length of . from origin to seamouth. The river is under the supervision of the ''Cauca Regional Corporation'' and the ''Cauca Valley Regional Autonomous Corporation'', and is navigable for above its junction with the Magdalena. File:Rio cauca popayan.JPG File:Salvajina.jpg File:Río Cauca. Puente Anacaro (3). Cartago - Ansermanuevo, Valle, Colombia.JPG File:Río Cauca.JPG File:Puentes en La Pintada 01.jpg File:Puente de Occidente.JPG File:El río Cauca.jpg Environmental issues On November 18, 2007, Colombian newspaper '' El Tiempo'' reported that the river was receiving an average of 500 tons of residual was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panicle
A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a panicle are often racemes. A panicle may have determinate or indeterminate growth. This type of inflorescence is largely characteristic of grasses such as oat and crabgrass, as well as other plants such as pistachio and mamoncillo. Botanists use the term paniculate in two ways: "having a true panicle inflorescence" as well as "having an inflorescence with the form but not necessarily the structure of a panicle". Corymb A corymb may have a paniculate branching structure, with the lower flowers having longer pedicels than the upper, thus giving a flattish top superficially resembling an umbel. Many species in the subfamily Amygdaloideae, such as hawthorns and rowans, produce their flowers in corymbs. up'' Sorbus glabrescens'' corymb with fruit See ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiller (botany)
A tiller is a shoot that arises from the base of a grass plant. The term refers to all shoots that grow after the initial parent shoot grows from a seed. Tillers are segmented, each segment possessing its own two-part leaf. They are involved in vegetative propagation and, in some cases, also seed production. "Tillering" refers to the production of side shoots and is a property possessed by many species in the grass family. This enables them to produce multiple stems (tillers) starting from the initial single seedling. This ensures the formation of dense tufts and multiple seed heads. Tillering rates are heavily influenced by soil water quantity. When soil moisture is low, grasses tend to develop more sparse and deep root systems (as opposed to dense, lateral systems). Thus, in dry soils, tillering is inhibited: the lateral nature of tillering is not supported by lateral root growth. See also *Crown (botany) The crown of a plant refers to the total of an individual plant's ... [...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] |
RNA Silencing
RNA silencing or RNA interference refers to a family of gene silencing effects by which gene expression is negatively regulated by non-coding RNAs such as microRNAs. RNA silencing may also be defined as sequence-specific regulation of gene expression triggered by double-stranded RNA (dsRNA). RNA silencing mechanisms are highly conserved in most eukaryotes. The most common and well-studied example is RNA interference (RNAi), in which endogenously expressed microRNA (miRNA) or exogenously derived small interfering RNA (siRNA) induces the degradation of complementary messenger RNA. Other classes of small RNA have been identified, including piwi-interacting RNA (piRNA) and its subspecies repeat associated small interfering RNA (rasiRNA). Background RNA silencing describes several mechanistically related pathways which are involved in controlling and regulating gene expression. RNA silencing pathways are associated with the regulatory activity of small non-coding RNAs (approximately 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cap Snatching
The first step of transcription for some negative, single-stranded RNA viruses is cap snatching, in which the first 10 to 20 residues of a host cell RNA are removed (snatched) and used as the 5′ cap and primer to initiate the synthesis of the nascent viral mRNA. The viral RNA-dependent RNA polymerase (RdRp) can then proceed to replicate the negative-sense genome from the positive-sense template. Cap-snatching also explains why some viral mRNA have 5’ terminal extensions of 10-20 nucleotides that are not encoded for in the genome. Examples of viruses that engage in cap-snatching include influenza viruses ('' Orthomyxoviridae''), Lassa virus ('' Arenaviridae''), hantaan virus (''Hantaviridae'') and rift valley fever virus (''Phenuiviridae''). Most viruses snatch 15-20 nucleotides except for the families ''Arenaviridae'' and ''Nairoviridae'' and the genus Thogotovirus (''Orthomyxoviridae'') which use a shorter strand. In the influenza virus, cap snatching occurs in the nucleus o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Transmission
Vertical transmission of symbionts is the transfer of a microbial symbiont from the parent directly to the offspring. Many metazoan species carry symbiotic bacteria which play a mutualistic, commensal, or parasitic role. A symbiont is acquired by a host via horizontal, vertical, or mixed transmission. Implications Complex interdependence occurs between host and symbiont. The genetic pool of the symbiont is generally smaller and more subject to genetic drift. In true vertical transmission, the evolutionary outcomes of the host and symbiont are linked. If there is mixed transmission, new genetic material may be introduced. Generally, symbionts settle into specific niches and can even transfer part of their genome into the host nucleus. Evolutionary consequences Benefits The mechanism promotes tightly coupled evolutionary pressure, which causes the host and symbiont to function as a holobiont. Disadvantages Evolutionary bottlenecks lead to less symbiont diversity, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phloem
Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is called translocation. In trees, the phloem is the innermost layer of the bark (botany), bark, hence the name, derived from the Ancient Greek word (''phloiós''), meaning "bark". The term was introduced by Carl Nägeli in 1858. Structure Phloem tissue consists of conducting Cell (biology), cells, generally called sieve elements, Ground tissue#Parenchyma, parenchyma cells, including both specialized companion cells or albuminous cells and unspecialized cells and supportive cells, such as fibres and sclereids. Conducting cells (sieve elements) Sieve elements are the type of cell that are responsible for transporting sugars throughout the plant. At maturity they lack a Cell nucleus, nucleus and have very few organelles, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delphacidae
Delphacidae is a family of planthoppers containing about 2000 species, distributed worldwide. Delphacids are separated from other "hoppers" by the prominent spur on the tibia of the hindleg. Diet and Pest species All species are phytophagous, many occurring on various grasses. Some species are significant pests and important vectors for cereal pathogens; for example: * The rice brown planthopper, '' Nilaparvata lugens'' (Stål) * The white-backed planthopper (rice), '' Sogatella furcifera'' (Horváth, 1899) * The sugarcane planthopper, '' Perkinsiella saccharicida'' Kirkaldy, 1903 Subfamilies, tribes and selected genera ''Fulgoromorpha Lists On the Web'' includes the following tribes and genera (complete lists where tribe unassigned): Asiracinae Auth.: Motschulsky, 1863 * Tribe Asiracini Motschulsky, 1863 * Tribe Eodelphacini Emeljanov, 1995 * Tribe Idiosystatini Emeljanov, 1995 * Tribe Neopunanini Emeljanov, 1995 * Tribe Platysystatini Emeljanov, 1995 * Tribe Tetrasteirini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
