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Mutation Breeding
Mutation breeding, sometimes referred to as "variation breeding", is the process of exposing seeds to chemicals, radiation, or enzymes in order to generate mutants with desirable traits to be bred with other cultivars. Plants created using mutagenesis are sometimes called mutagenic plants or mutagenic seeds. From 1930 to 2014 more than 3200 mutagenic plant varieties were released that have been derived either as direct mutants (70%) or from their progeny (30%). Crop plants account for 75% of released mutagenic species with the remaining 25% ornamentals or decorative plants. However, although the FAO/IAEA reported in 2014 that over 1,000 mutant varieties of major staple crops were being grown worldwide,(2014Plant Breeding and Genetics Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Retrieved 31 July 2014 it is unclear how many of these varieties are currently used in agriculture or horticulture around the world, as these seeds are not always identified or lab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemicals
A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combined without reacting, they may form a chemical mixture. If a mixture is separated to isolate one chemical substance to a desired degree, the resulting substance is said to be chemically pure. Chemical substances can exist in several different physical states or phases (e.g. solids, liquids, gases, or plasma) without changing their chemical composition. Substances transition between these phases of matter in response to changes in temperature or pressure. Some chemical substances can be combined or converted into new substances by means of chemical reactions. Chemicals that do not possess this ability are said to be inert. Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bonded to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutagenesis
Mutagenesis () is a process by which the genetic information of an organism is changed by the production of a mutation. It may occur spontaneously in nature, or as a result of exposure to mutagens. It can also be achieved experimentally using laboratory procedures. A mutagen is a mutation-causing agent, be it chemical or physical, which results in an increased rate of mutations in an organism's genetic code. In nature mutagenesis can lead to cancer and various heritable diseases, and it is also a driving force of evolution. Mutagenesis as a science was developed based on work done by Hermann Muller, Charlotte Auerbach and J. M. Robson in the first half of the 20th century. History DNA may be modified, either naturally or artificially, by a number of physical, chemical and biological agents, resulting in mutations. Hermann Muller found that "high temperatures" have the ability to mutate genes in the early 1920s, and in 1927, demonstrated a causal link to mutation upon experimen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TIARA
A tiara (, ) is a head ornament adorned with jewels. Its origins date back to ancient Greco-Roman world. In the late 18th century, the tiara came into fashion in Europe as a prestigious piece of jewelry to be worn by women at formal occasions. The basic shape of the modern tiara is a semicircle, usually made of silver, gold, or platinum and richly decorated with precious stones, pearls, or cameos. Tiaras were extremely popular during the late 19th century and were worn at events where the dress code was white tie. After World War I, wearing a tiara gradually fell out of fashion, except for official occasions at a royal court. Interest in tiaras has increased again since the beginning of the 21st century. The word ''tiara'' is often used interchangeably with the word ''diadem''. Description The basic shape of the modern tiara is a semi-circle, usually made of silver, gold or platinum. Tiaras have also been made from tortoiseshell, coral and quartz, and in the 20th century ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deletion (genetics)
In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) (sign: Δ) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is left out during DNA replication. Any number of nucleotides can be deleted, from a single base to an entire piece of chromosome. Some chromosomes have fragile spots where breaks occur, which result in the deletion of a part of the chromosome. The breaks can be induced by heat, viruses, radiation, or chemical reactions. When a chromosome breaks, if a part of it is deleted or lost, the missing piece of chromosome is referred to as a deletion or a deficiency. For synapsis to occur between a chromosome with a large intercalary deficiency and a normal complete homolog, the unpaired region of the normal homolog must loop out of the linear structure into a deletion or compensation loop. The smallest single base deletion mutations occur by a single base flipping in the template DNA, followed by te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Beam
An ion beam is a beam of ions, a type of charged particle beam. Ion beams have many uses in electronics manufacturing (principally ion implantation) and other industries. There are many ion beam sources, some derived from the mercury vapor thrusters developed by NASA in the 1960s. The most widely used ion beams are of singly-charged ions. Units Ion current density is typically measured in mA/cm2, and ion energy in electronvolts (eV). The use of eV is convenient for converting between voltage and energy, especially when dealing with singly charged ion beams. Broad-beam ion sources Most commercial applications use two popular types of ion source, gridded and gridless, which differ in current and power characteristics and the ability to control ion trajectories. In both cases electrons are needed to generate an ion beam. The most common types of electron emitter are hot filament and hollow cathode. Gridded ion source In a gridded ion source, DC or RF discharge are u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function (mathematics), function assigning a Euclidean vector, vector to each point of space, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmic Radiation
Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own galaxy, and from distant galaxies. Upon impact with Earth's atmosphere, cosmic rays produce showers of secondary particles, some of which reach the surface, although the bulk are deflected off into space by the magnetosphere or the heliosphere. Cosmic rays were discovered by Victor Hess in 1912 in balloon experiments, for which he was awarded the 1936 Nobel Prize in Physics. Direct measurement of cosmic rays, especially at lower energies, has been possible since the launch of the first satellites in the late 1950s. Particle detectors similar to those used in nuclear and high-energy physics are used on satellites and space probes for research into cosmic rays. Data from the Fermi Space Telescope (2013) have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microgravity
Weightlessness is the complete or near-complete absence of the sensation of weight, i.e., zero apparent weight. It is also termed zero g-force, or zero-g (named after the g-force) or, incorrectly, zero gravity. Weight is a measurement of the force on an object at rest in a relatively strong gravitational field (such as on the surface of the Earth). These weight-sensations originate from contact with supporting floors, seats, beds, scales, and the like. A sensation of weight is also produced, even when the gravitational field is zero, when contact forces act upon and overcome a body's inertia by mechanical, non- gravitational forces- such as in a centrifuge, a rotating space station, or within an accelerating vehicle. When the gravitational field is non-uniform, a body in free fall experiences tidal forces and is not stress-free. Near a black hole, such tidal effects can be very strong, leading to ''spaghettification''. In the case of the Earth, the effects are minor, especiall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annual Review Of Phytopathology
The ''Annual Review of Phytopathology'' is a peer-reviewed academic journal that publishes review articles about phytopathology, the study of diseases that affect plants. It was first published in 1963 as the result of a collaboration between the American Phytopathological Society and the nonprofit publisher Annual Reviews. As of 2024, ''Journal Citation Reports'' lists the journal's 2023 impact factor as 9.1, ranking it tenth of 265 journal titles in the category "Plant Sciences". As of 2023, it is being published as open access, under the Subscribe to Open model. Its current editors are John M. McDowell and Gwyn A. Beattie. History In the 1950s, the American Phytopathological Society had intended to publish its own journal to cover significant developments in the field of phytopathology, or plant diseases. However, the nonprofit publisher Annual Reviews offered to publish the journal for them, and they agreed due to their publishing experience. In 1961, the American Phyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Pathogen
Plant diseases are 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, vertebrates, or other pests that affect plant health by eating plant tissues and causing injury that may admit plant pathogens. The study of plant disease is called plant pathology. Plant pathogens Fungi Most phytopathogenic fungi are Ascomycetes or Basidiomycetes. They reproduce both sexually and asexually via the production of spores and other structures. Spores may be spread long distances by air or water, or they may be soil borne. Many soil inhabiting fungi are capable of living saprotrophically, carrying out the role of their life cycle in the soil. These are facultative saprotrophs. Fungal diseases ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virulence
Virulence is a pathogen's or microorganism's ability to cause damage to a host. In most cases, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its ability to cause disease—is determined by its virulence factors. In the specific context of gene for gene systems, often in plants, virulence refers to a pathogen's ability to infect a resistant host. Virulence can also be transferred using a plasmid. The noun ''virulence'' (Latin noun ) derives from the adjective ''virulent'', meaning disease severity. The word ''virulent'' derives from the Latin word ''virulentus'', meaning "a poisoned wound" or "full of poison". The term ''virulence'' does not only apply to viruses. From an ecological standpoint, virulence is the loss of fitness induced by a parasite upon its host. Virulence can be understood in terms of proximate causes—those specific traits of the pathogen that help make the host ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Knockout
Gene knockouts (also known as gene deletion or gene inactivation) are a widely used genetic engineering technique that involves the gene targeting, targeted removal or inactivation of a specific gene within an organism's genome. This can be done through a variety of methods, including homologous recombination, CRISPR gene editing, CRISPR-Cas9, and transcription activator-like effector nuclease, TALENs. One of the main advantages of gene knockouts is that they allow researchers to study the function of a specific gene in vivo, and to understand the role of the gene in normal development and physiology as well as in the pathology of diseases. By studying the phenotype of the organism with the knocked out gene, researchers can gain insights into the biological processes that the gene is involved in. There are two main types of gene knockouts: complete and conditional. A complete gene knockout permanently inactivates the gene, while a conditional gene knockout allows for the gene to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
