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Pathosystem
A pathosystem is a subsystem of an ecosystem and is defined by the phenomenon of parasitism. A plant pathosystem is one in which the host species is a plant. The parasite is any species in which the individual spends a significant part of its lifespan inhabiting one host individual and obtaining nutrients from it. The parasite may thus be an insect, mite, nematode, parasitic Angiosperm, fungus, bacterium, mycoplasma, virus or viroid. Other consumers, however, such as mammalian and avian herbivores, which graze populations of plants, are normally considered to be outside the conceptual boundaries of the plant pathosystem. A host has the property of resistance to a parasite. And a parasite has the property of parasitic ability on a host. Parasitism is the interaction of these two properties. The main feature of the pathosystem concept is that it concerns parasitism, and it is not concerned with the study of either the host or parasite on its own. Another feature of the pathosystem co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Resistance
The term vertical resistance, used commonly in context of plant selection, was first used by J.E. VanderplankVanderplank, J.E. (1963) Plant Diseases: Epidemics and Control. Academic Press, New York and London, 349pp. to describe single-gene resistance. This contrasted the term horizontal resistance which was used to describe many-gene resistance. Raoul A. Robinson Robinson, Raoul A. (1976) Plant Pathosystems. Springer-Verlag, Berlin, Heidelberg, New York, 184pp. further refined the definition of vertical resistance, emphasizing that in vertical resistance there are single genes for resistance in the host plant, and there are also single genes for parasitic ability in the parasite. This phenomenon is known as the gene-for-gene relationship The gene-for-gene relationship was discovered by Harold Henry Flor who was working with rust (''Melampsora lini'') of flax ('' Linum usitatissimum''). Flor showed that the inheritance of both resistance in the host and parasite ability to cause d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizontal Resistance
In genetics, the term horizontal resistance was first used by J.E. VanderplankVanderplank, J.E. (1963) Plant Diseases: Epidemics and Control. Academic Press, New York and London, 349pp. to describe many-gene resistance, which is sometimes also called generalized resistance. This contrasts with the term vertical resistance The term vertical resistance, used commonly in context of plant selection, was first used by J.E. VanderplankVanderplank, J.E. (1963) Plant Diseases: Epidemics and Control. Academic Press, New York and London, 349pp. to describe single-gene resistan ... which was used to describe single-gene resistance. Raoul A. Robinson Robinson, Raoul A. (1976) Plant Pathosystems. Springer-Verlag, Berlin, Heidelberg, New York, 184pp. further refined the definition of horizontal resistance. Unlike vertical resistance and parasitic ability, horizontal resistance and horizontal parasitic ability are entirely independent of each other in genetic terms. In the first round of breedin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and microbes. Ecosystems are controlled by external and internal Environmental factor, factors. External factors such as climate, parent material which forms the soil and topography, control the overall structure of an ecosystem but are not themselves influe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antigen
In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. The term ''antigen'' originally referred to a substance that is an antibody generator. Antigens can be proteins, peptides (amino acid chains), polysaccharides (chains of monosaccharides/simple sugars), lipids, or nucleic acids. Antigens are recognized by antigen receptors, including antibodies and T-cell receptors. Diverse antigen receptors are made by cells of the immune system so that each cell has a specificity for a single antigen. Upon exposure to an antigen, only the lymphocytes that recognize that antigen are activated and expanded, a process known as clonal selection. In most cases, an antibody can only react to and bind one specific antigen; in some instances, however, antibodies may cross-react and bind more than one antigen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evergreen
In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which completely lose their foliage during the winter or dry season. Evergreen species There are many different kinds of evergreen plants, both trees and shrubs. Evergreens include: *Most species of conifers (e.g., pine, hemlock, blue spruce, and red cedar), but not all (e.g., larch) *Live oak, holly, and "ancient" gymnosperms such as cycads *Most angiosperms from frost-free climates, and rainforest trees *All Eucalypts * Clubmosses and relatives * Bamboos The Latin binomial term , meaning "always green", refers to the evergreen nature of the plant, for instance :'' Cupressus sempervirens'' (a cypress) :''Lonicera sempervirens'' (a honeysuckle) :''Sequoia sempervirens'' (a sequoia) Leaf longevity in evergreen plants varies from a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raoul A
__NOTOC__ Raoul is a French variant of the male given name Ralph or Rudolph, and a cognate of Raul. Raoul may also refer to: Given name * Raoul Berger, American legal scholar * Raoul Bova, Italian actor * Radulphus Brito (Raoul le Breton, died 1320), grammarian * See Lament for the Makaris for Roull of Corstorphin and Roull of Aberdene; fifteenth-century poets * Raoul de Godewaersvelde, French singer * Rudolph, Duke of Burgundy; also known as Raoul, Duke of Burgundy (and later king of the Franks), son of Richard of Autun * Raoul Heertje, Dutch stand-up comedian * Raoul Moat, English fugitive and gunman at the centre of the 2010 Northumbria Police manhunt * Raoul of Turenne or Saint-Raoul, archbishop of Bourges, 840–866 * Raoul (founder of Vaucelles Abbey) or Saint Raoul * Raoul Wallenberg, Swedish humanitarian * Raoul Walsh (1887–1980), film director * Raoul, alleged conspirator in the assassination of Martin Luther King Jr. Surname * Raoul (Byzantine family), Byzantine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epidemic
An epidemic (from Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of patients among a given population within an area in a short period of time. Epidemics of infectious diseases are generally caused by several factors including a significant change in the ecology of the areal population (e.g., increased stress maybe additional reason or increase in the density of a vector species), the introduction of an emerging pathogen to an areal population (by movement of pathogen or host) or an unexpected genetic change that is in the pathogen reservoir. Generally, epidemics concerns with the patterns of infectious disease spread. An epidemic may occur when host immunity to either an established pathogen or newly emerging novel pathogen is suddenly reduced below that found in the endemic equilibrium and the transmission threshold is exceeded. For example, in meningococcal infections, an attack rate in excess of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homogeneity
Homogeneity and heterogeneity are concepts often used in the sciences and statistics relating to the Uniformity (chemistry), uniformity of a Chemical substance, substance or organism. A material or image that is homogeneous is uniform in composition or character (i.e. color, shape, size, weight, height, distribution, texture, language, income, disease, temperature, radioactivity, architectural design, etc.); one that is heterogeneous is distinctly nonuniform in at least one of these qualities. Mixture, Heterogeneous Mixtures, in chemistry, is where certain elements are unwillingly combined and, when given the option, will separate. Etymology and spelling The words ''homogeneous'' and ''heterogeneous'' come from Medieval Latin ''homogeneus'' and ''heterogeneus'', from Ancient Greek ὁμογενής (''homogenēs'') and ἑτερογενής (''heterogenēs''), from ὁμός (''homos'', “same”) and ἕτερος (''heteros'', “other, another, different”) respectively, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloning
Cloning is the process of producing individual organisms with identical or virtually identical DNA, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction. In the field of biotechnology, cloning is the process of creating cloned organisms (copies) of cells and of DNA fragments (molecular cloning). Etymology Coined by Herbert J. Webber, the term clone derives from the Ancient Greek word (), ''twig'', which is the process whereby a new plant is created from a twig. In botany, the term ''lusus'' was used. In horticulture, the spelling ''clon'' was used until the early twentieth century; the final ''e'' came into use to indicate the vowel is a "long o" instead of a "short o". Since the term entered the popular lexicon in a more general context, the spelling ''clone'' has been used exclusively. Natural cloning Cloning is a natural form of reproduction that has allowed life forms to spread for hundreds of millions of years. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infection
An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable disease, is an illness resulting from an infection. Infections can be caused by a wide range of pathogens, most prominently bacteria and viruses. Hosts can fight infections using their immune system. Mammalian hosts react to infections with an innate response, often involving inflammation, followed by an adaptive response. Specific medications used to treat infections include antibiotics, antivirals, antifungals, antiprotozoals, and antihelminthics. Infectious diseases resulted in 9.2 million deaths in 2013 (about 17% of all deaths). The branch of medicine that focuses on infections is referred to as infectious disease. Types Infections are caused by infectious agents (pathogens) including: * Bacteria (e.g. '' Mycobacterium tubercul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polygene
A polygene is a member of a group of non- epistatic genes that interact additively to influence a phenotypic trait, thus contributing to multiple-gene inheritance (polygenic inheritance, multigenic inheritance, quantitative inheritance), a type of non-Mendelian inheritance, as opposed to single-gene inheritance, which is the core notion of Mendelian inheritance. The term "monozygous" is usually used to refer to a hypothetical gene as it is often difficult to distinguish the effect of an individual gene from the effects of other genes and the environment on a particular phenotype. Advances in statistical methodology and high throughput sequencing are, however, allowing researchers to locate candidate genes for the trait. In the case that such a gene is identified, it is referred to as a quantitative trait locus (QTL). These genes are generally pleiotropic as well. The genes that contribute to type 2 diabetes are thought to be mostly polygenes. In July 2016, scientists reported identi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-crossing
Backcrossing is a crossing of a hybrid with one of its parents or an individual genetically similar to its parent, to achieve offspring with a genetic identity closer to that of the parent. It is used in horticulture, animal breeding, and production of gene knockout organisms. Backcrossed hybrids are sometimes described with acronym "BC"; for example, an F1 hybrid crossed with one of its parents (or a genetically similar individual) can be termed a BC1 hybrid, and a further cross of the BC1 hybrid to the same parent (or a genetically similar individual) produces a BC2 hybrid. Plants Advantages * If the recurrent parent is an elite genotype, at the end of the backcrossing programme, an elite genotype is recovered. * As no "new" recombination results, the elite combination is not lost. Disadvantages * It works poorly for quantitative traits. * It is more restricted for recessive traits. * In practice, sections of genome from the nonrecurrent parents are often still present and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
