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Cytokinins
Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence. There are two types of cytokinins: adenine-type cytokinins represented by kinetin, zeatin, and 6-benzylaminopurine, and phenylurea-type cytokinins like diphenylurea and thidiazuron (TDZ). Most adenine-type cytokinins are synthesized in roots. Cambium and other actively dividing tissues also synthesize cytokinins. No phenylurea cytokinins have been found in plants. Cytokinins participate in local and long-distance signalling, with the same transport mechanism as purines and nucleosides. Typically, cytokinins are transported in the xylem. Cytokinins act in concert with auxin, another plant growth hormone. The two are complementary, having generally opposite effects. History The idea of specific substances required ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Hormone
Plant hormone (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pathogen defense, stress tolerance and through to reproductive development. Unlike in animals (in which hormone production is restricted to specialized glands) each plant cell is capable of producing hormones. Went and Thimann coined the term "phytohormone" and used it in the title of their 1937 book. Phytohormones occur across the plant kingdom, and even in algae, where they have similar functions to those seen in higher plants. Some phytohormones also occur in microorganisms, such as unicellular fungi and bacteria, however in these cases they do not play a hormonal role and can better be regarded as secondary metabolites. Characteristics The word hormone is derived from Greek, meaning ''set in motion''. Plant hormones affect gene expre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auxin
Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essential for plant body development. The Dutch biologist Frits Warmolt Went first described auxins and their role in plant growth in the 1920s. Kenneth V. Thimann became the first to isolate one of these phytohormones and to determine its chemical structure as indole-3-acetic acid (IAA). Went and Thimann co-authored a book on plant hormones, ''Phytohormones'', in 1937. Overview Auxins were the first of the major plant hormones to be discovered. They derive their name from the Greek word αυξειν (''auxein'' – "to grow/increase"). Auxin is present in all parts of a plant, although in very different concentrations. The concentration in each position is crucial developmental information, so it is subject to tight regulation through both me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphenylurea
1,3-Diphenylurea is a phenylurea-type compound with the formula (PhNH)2CO (Ph = C6H5). It is a colorless solid that is prepared by transamidation of urea with aniline. DPU is a cytokinin Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and lea ..., a type of plant hormone that induces flower development. It occurs in coconut milk. The cytokinin effect of DPU is relatively low, but other more potent phenylurea-type cytokinins have been reported.Effect of cytokinin-active phenylurea derivatives on shoot multiplication. T. Genkov and I. Ivanova, Bulg. J. Plant Physiol., 1995, 21(1), pages 73–83link to article at researchgate References External links * Cytokinins Ureas {{Organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokine
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrine, paracrine and endocrine signaling as immunomodulating agents. Cytokines include chemokines, interferons, interleukins, lymphokines, and tumour necrosis factors, but generally not hormones or growth factors (despite some overlap in the terminology). Cytokines are produced by a broad range of cells, including immune cells like macrophages, B lymphocytes, T lymphocytes and mast cells, as well as endothelial cells, fibroblasts, and various stromal cells; a given cytokine may be produced by more than one type of cell. They act through cell surface receptors and are especially important in the immune system; cytokines modulate the balance between humoral and cell-based immune responses, and they regulate the maturati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endosperm
The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This can make endosperm a source of nutrition in animal diet. For example, wheat endosperm is ground into flour for bread (the rest of the grain is included as well in whole wheat flour), while barley endosperm is the main source of sugars for beer production. Other examples of endosperm that forms the bulk of the edible portion are coconut "meat" and coconut "water", and corn. Some plants, such as orchids, lack endosperm in their seeds. Origin of endosperm Ancestral flowering plants have seeds with small embryos and abundant endosperm. The evolutionary development of flowering plants trends towards plants with mature seeds with little or no endo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gottlieb Haberlandt
Gottlieb Haberlandt (28 November 1854 – 30 January 1945) was an Austrian botanist. He was the son of European 'soybean' pioneer Professor Friedrich J. Haberlandt. His son Ludwig Haberlandt was an early reproductive physiologist now given credit as the 'grandfather' of the birth control pill. Haberlandt first pointed out the possibilities of the culture of isolated tissues, plant tissue culture Plant tissue culture is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. It is widely used to produce clones of a plant in a method known .... He suggested that the potentialities of individual cells via tissue culture and also suggested that the reciprocal influences of tissues on one another could be determined by this method. Since Haberlandt's original assertions methods for tissue and cell culture have been realized, leading to significant discoveries in Biology and Medicine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parenchyma (botany)
The ground tissue of plants includes all tissues that are neither dermal nor vascular. It can be divided into three types based on the nature of the cell walls. # Parenchyma cells have thin primary walls and usually remain alive after they become mature. Parenchyma forms the "filler" tissue in the soft parts of plants, and is usually present in cortex, pericycle, pith, and medullary rays in primary stem and root. # Collenchyma cells have thin primary walls with some areas of secondary thickening. Collenchyma provides extra mechanical and structural support, particularly in regions of new growth. # Sclerenchyma cells have thick lignified secondary walls and often die when mature. Sclerenchyma provides the main structural support to a plant. Parenchyma Parenchyma is a versatile ground tissue that generally constitutes the "filler" tissue in soft parts of plants. It forms, among other things, the cortex (outer region) and pith (central region) of stems, the cortex of roots, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potato
The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern United States to southern Chile. The potato was originally believed to have been domesticated by Native Americans independently in multiple locations,University of Wisconsin-Madison, ''Finding rewrites the evolutionary history of the origin of potatoes'' (2005/ref> but later genetic studies traced a single origin, in the area of present-day southern Peru and extreme northwestern Bolivia. Potatoes were domesticated there approximately 7,000–10,000 years ago, from a species in the '' Solanum brevicaule'' complex. Lay summary: In the Andes region of South America, where the species is indigenous, some close relatives of the potato are cultivated. Potatoes were introduced to Europe from the Americas by the Spanish in the second half of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johannes Van Overbeek
Johannes is a Medieval Latin form of the personal name that usually appears as "John" in English language contexts. It is a variant of the Greek and Classical Latin variants (Ιωάννης, '' Ioannes''), itself derived from the Hebrew name '' Yehochanan'', meaning "Yahweh is gracious". The name became popular in Northern Europe, especially in Germany because of Christianity. Common German variants for Johannes are ''Johann'', ''Hannes'', ''Hans'' (diminutized to ''Hänschen'' or ''Hänsel'', as known from "''Hansel and Gretel''", a fairy tale by the Grimm brothers), ''Jens'' (from Danish) and '' Jan'' (from Dutch, and found in many countries). In the Netherlands, Johannes was without interruption the most common masculine birth name until 1989. The English equivalent for Johannes is John. In other languages *Joan, Jan, Gjon, Gjin and Gjovalin in Albanian *'' Yoe'' or '' Yohe'', uncommon American form''Dictionary of American Family Names'', Oxford University Press, 2013. *Yaḥy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Datura
''Datura'' is a genus of nine species of highly poisonous, vespertine-flowering plants belonging to the nightshade family Solanaceae. They are commonly known as thornapples or jimsonweeds, but are also known as devil's trumpets (not to be confused with angel's trumpets, which are placed in the closely related genus ''Brugmansia''). Other English common names include moonflower, devil's weed, and hell's bells. All species of ''Datura'' are extremely poisonous and potentially psychoactive, especially their seeds and flowers, which can cause respiratory depression, arrhythmias, fever, delirium, hallucinations, anticholinergic syndrome, psychosis, and even death if taken internally. Due to their effects and symptoms, they have occasionally been used not only as poisons, but also as hallucinogens by various groups throughout history. Traditionally, psychoactive administration of ''Datura'' species has often been associated with witchcraft and sorcery or similar practices in m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coconut
The coconut tree (''Cocos nucifera'') is a member of the palm tree family (Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or the fruit, which botanically is a drupe, not a nut. The name comes from the old Portuguese word '' coco'', meaning "head" or "skull", after the three indentations on the coconut shell that resemble facial features. They are ubiquitous in coastal tropical regions and are a cultural icon of the tropics. The coconut tree provides food, fuel, cosmetics, folk medicine and building materials, among many other uses. The inner flesh of the mature seed, as well as the coconut milk extracted from it, form a regular part of the diets of many people in the tropics and subtropics. Coconuts are distinct from other fruits because their endosperm contains a large quantity of clear liquid, called ''coconut water'' or ''coconut juice''. Mature, ripe coconuts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aleksander Jabłoński
Professor Aleksander Jabłoński (born 26 February 1898 in Woskresenówka, in Imperial Russia, died 9 September 1980 in Skierniewice, Poland) was a Polish physicist and member of the Polish Academy of Sciences. His research was in molecular spectroscopy and photophysics. Life and career He was born on 26 February 1898 in Woskresenówka near Kharkiv in Imperial Russia. He attended ''Gymnasium'' high school in Kharkiv as well as a music school where he learned to play the violin under supervision of Konstanty Gorski. In 1916, he started to study physics at the University of Kharkiv. During the World War I he served in the Polish I Corps in Russia. After the war he settled in Warsaw in 1918. In 1919-1920 he fought for Poland against aggression by Soviet Russia (and was consequently decorated with the Polish Cross of Valour). Jabłoński initially studied the violin at Warsaw Conservatory, under the virtuoso Stanisław Barcewicz, but later switched to science. He receiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
