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Potato Spindle Tuber Viroid
The potato spindle tuber viroid (PSTVd) was the first viroid to be identified.Discovery of Viroids
PSTVd is a small, single stranded molecule closely related to the chrysanthemum stunt viroid. Present within the viroidal RNA is the common to its genus. The natural hosts are

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Viroid
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economic importance to humans varies widely. The first discoveries of viroids in the 1970s triggered the historically third major extension of the biosphere—to include smaller lifelike entities —after the discoveries in 1675 by Antonie van Leeuwenhoek (of the "subvisible" microorganisms) and in 1892–1898 by Dmitri Iosifovich Ivanovsky and Martinus Beijerinck (of the "submicroscopic" viruses). The unique properties of viroids have been recognized by the International Committee on Taxonomy of Viruses, in creating a new order of subviral agents. The first recognized viroid, the pathogenic agent of the potato spindle tuber disease, was discovered, initially molecularly characterized, and named by Theodor Otto Diener, plant pathologist a ...
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Annual Reviews (publisher)
Annual Reviews is an independent, non-profit academic publishing company based in San Mateo, California. As of 2021, it publishes 51 journals of review articles and ''Knowable Magazine'', covering the fields of life, biomedical, physical, and social sciences. Review articles are usually “peer-invited” solicited submissions, often planned one to two years in advance, which go through a peer-review process. The organizational structure has three levels: a volunteer board of directors, editorial committees of experts for each journal, and paid employees. Annual Reviews' stated mission is to synthesize and integrate knowledge "for the progress of science and the benefit of society". The first Annual Reviews journal, the ''Annual Review of Biochemistry'', was published in 1932 under the editorship of Stanford University chemist J. Murray Luck, who wanted to create a resource that provided critical reviews on contemporary research. The second journal was added in 1939. By ...
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Viral Plant Pathogens And Diseases
Viral means "relating to viruses" (small infectious agents). Viral may also refer to: Viral behavior, or virality Memetic behavior likened that of a virus, for example: * Viral marketing, the use of existing social networks to spread a marketing message * Viral phenomenon, relating to contagion theory or the "virality" of network culture, such as a meme * Viral video, a video that quickly attains a high popularity Titled works * ''Viral'' (2016 American film), a 2016 American science fiction horror drama * ''Viral'' (2016 Hindi film), an Indian Bollywood film based on social media * ''Viral'' (web series), a 2014 Brazilian comedy web series * '' V/H/S: Viral'', an American anthology horror film * '' Viral: The Search for the Origin of COVID-19'', a book by Alina Chand and Matt Ridley See also * ''Virals'', a novel series by Kathy Reichs * Virulence Virulence is a pathogen's or microorganism's ability to cause damage to a host. In most, especially in animal system ...
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Viroids
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economic importance to humans varies widely. The first discoveries of viroids in the 1970s triggered the historically third major extension of the biosphere—to include smaller lifelike entities —after the discoveries in 1675 by Antonie van Leeuwenhoek (of the "subvisible" microorganisms) and in 1892–1898 by Dmitri Iosifovich Ivanovsky and Martinus Beijerinck (of the "submicroscopic" viruses). The unique properties of viroids have been recognized by the International Committee on Taxonomy of Viruses, in creating a new order of subviral agents. The first recognized viroid, the pathogenic agent of the potato spindle tuber disease, was discovered, initially molecularly characterized, and named by Theodor Otto Diener, plant pathologist a ...
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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, ...
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Nucleotide
Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all life-forms on Earth. Nucleotides are obtained in the diet and are also synthesized from common nutrients by the liver. Nucleotides are composed of three subunit molecules: a nucleobase, a five-carbon sugar (ribose or deoxyribose), and a phosphate group consisting of one to three phosphates. The four nucleobases in DNA are guanine, adenine, cytosine and thymine; in RNA, uracil is used in place of thymine. Nucleotides also play a central role in metabolism at a fundamental, cellular level. They provide chemical energy—in the form of the nucleoside triphosphates, adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP) and uridine triphosphate (UTP)—throughout the cell for the many cellular func ...
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Potato Leafroll Virus
Potato leafroll virus (PLRV) is a member of the genus ''Polerovirus'' and family ''Solemoviridae''. The phloem limited positive sense RNA virus infects potatoes and other members of the family Solanaceae. PLRV was first described by Quanjer ''et al.'' in 1916. PLRV is transmitted by aphids, primarily the green peach aphid, ''Myzus persicae''. PLRV is one of the most important potato viruses worldwide but particularly devastating in countries with limited resources and management. It can be responsible for individual plant yield losses of over 50%. One estimate suggests that PLRV is responsible for an annual global yield loss of 20 million tons. Symptoms include chlorosis, necrosis and leaf curling. Hosts and symptoms PLRV infects members of the family Solanaceae. The most economically important host is the Potato, ''Solanum tuberosum'' spp. In potato, symptoms of primary infection, infection in the growing season, occurs in the youngest leaves. Leaf margins become necrotic, ...
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Myzus Persicae
''Myzus persicae'', known as the green peach aphid, greenfly, or the peach-potato aphid, is a small green aphid belonging to the order Hemiptera. It is the most significant aphid pest of peach trees, causing decreased growth, shrivelling of the leaves and the death of various tissues. It also acts as a vector for the transport of plant viruses such as cucumber mosaic virus (CMV), potato virus Y (PVY) and tobacco etch virus (TEV). Potato virus Y and potato leafroll virus can be passed to members of the nightshade/potato family (Solanaceae), and various mosaic viruses to many other food crops. Originally described by Swiss entomologist Johann Heinrich Sulzer in 1776, its specific name is derived from the Latin genitive ''persicae,'' "of the peach". The syntype specimen of this species is located in the Illinois Natural History Survey Insect Collection. Life cycle Life cycle of the green peach aphid varies depending on temperature. A fully completed generation takes approximately 1 ...
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Aphid
Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A typical life cycle involves flightless females giving live birth to female nymphs—who may also be already pregnant, an adaptation scientists call telescoping generations—without the involvement of males. Maturing rapidly, females breed profusely so that the number of these insects multiplies quickly. Winged females may develop later in the season, allowing the insects to colonize new plants. In temperate regions, a phase of sexual reproduction occurs in the autumn, with the insects often overwintering as eggs. The life cycle of some species involves an alternation between two species of host plants, for example between an annual crop and a woody plant. Some species feed on only one type of plant, while others are generalists, coloni ...
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Theodor Otto Diener
Theodor Otto Diener (born 28 February 1921) is a Swiss-American plant pathologist. In 1971, he discovered that the causative agent of the potato spindle tuber disease is not a virus, but a novel agent, which consists solely of a short strand of single-stranded RNA without a protein capsid, eighty times smaller than the smallest viruses. He proposed to name it, and similar agents yet to be discovered, viroids. Viroids displaced viruses as the smallest known infectious agents. Biography Diener was born in Zürich, Switzerland. He attended the Swiss Federal Institute of Technology, from which he graduated with a Dr.sc.nat.ETH degree in 1946. After graduation, he worked as a research assistant at the Swiss Federal Experiment Station for Viticulture and Horticulture at Wädenswil, where he discovered on leaves of a cherry tree the first occurrence in more than 100 years of a rust fungus (''Puccinia cerasi''), a fungus which is common south of the Alps, but is rarely seen in the north. ...
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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 2022, ''Journal Citation Reports'' lists the journal's 2021 impact factor as 10.850, ranking it seventh of 238 journal titles in the category "Plant Sciences". Its current editors are Jan E. Leach and Steven E. Lindow. 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 Phytopathological Society compiled the editorial board of the journal at their annual meeting. ...
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