|
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 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 for ... [...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 meta ... [...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 ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Senescence
Plant senescence is the process of aging in plants. Plants have both stress-induced and age-related developmental aging. Chlorophyll degradation during leaf senescence reveals the carotenoids, such as anthocyanin and xanthophylls, which are the cause of autumn leaf color in deciduous trees. Leaf senescence has the important function of recycling nutrients, mostly nitrogen, to growing and storage organs of the plant. Unlike animals, plants continually form new organs and older organs undergo a highly regulated senescence program to maximize nutrient export. Hormonal regulation of senescence Programmed senescence seems to be heavily influenced by plant hormones. The hormones abscisic acid, ethylene, jasmonic acid and salicylic acid are accepted by most scientists as promoters of senescence, but at least one source lists gibberellins, brassinosteroids and strigolactone as also being involved. Cytokinins help to maintain the plant cell and expression of cytokinin biosynthesis g ... [...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 le ..., 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] |
Kinetin
Kinetin (/'kaɪnɪtɪn/) is a type of cytokinin, a class of plant hormone that promotes cell division. Kinetin was originally isolated by Carlos Miller and Skoog ''et al.'' as a compound from autoclaved herring sperm DNA that had cell division-promoting activity. It was given the name kinetin because of its ability to induce cell division, provided that auxin was present in the medium. Kinetin is often used in plant tissue culture for inducing formation of callus (in conjunction with auxin) and to regenerate shoot tissues from callus (with lower auxin concentration). For a long time, it was believed that kinetin was an artifact produced from the deoxyadenosine residues in DNA, which degrade on standing for long periods or when heated during the isolation procedure. Therefore, it was thought that kinetin does not occur naturally, but, since 1996, it has been shown by several researchers that kinetin exists naturally in the DNA of cells of almost all organisms tested so far, incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thidiazuron
Thidiazuron (TDZ) is a plant growth regulator. Applications Plant growth regulator The synthesis routes and their use as plant growth regulating agent were patented in the early 1980s by the German company Schering AG. Thidiazuron is taken up by the leaves and has a cytokinin-like behavior. It causes leaves to lose weight in a controlled manner prior to harvesting, without affecting the growth and maturation of the plant. This facilitates mechanical harvesting. It also accelerates the maturation process, because leaves do not block the sunlight. The plants later develop normal foliage. Thidiazuron can also be used as a herbicide, because an appropriate dose and timing of administration completely stops growth. The product was marketed by Aventis CropScience; later merged into Bayer CropScience. Brand names are Dropp (for use in the cultivation of cotton) or Revent (for use in fruit production). Dropp Ultra, Dropp UltraMax and Ginstar are products with a mixture of thidiazuron and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinetin
Kinetin (/'kaɪnɪtɪn/) is a type of cytokinin, a class of plant hormone that promotes cell division. Kinetin was originally isolated by Carlos Miller and Skoog ''et al.'' as a compound from autoclaved herring sperm DNA that had cell division-promoting activity. It was given the name kinetin because of its ability to induce cell division, provided that auxin was present in the medium. Kinetin is often used in plant tissue culture for inducing formation of callus (in conjunction with auxin) and to regenerate shoot tissues from callus (with lower auxin concentration). For a long time, it was believed that kinetin was an artifact produced from the deoxyadenosine residues in DNA, which degrade on standing for long periods or when heated during the isolation procedure. Therefore, it was thought that kinetin does not occur naturally, but, since 1996, it has been shown by several researchers that kinetin exists naturally in the DNA of cells of almost all organisms tested so far, incl ... [...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 endosp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeatin
Zeatin is a cytokinin derived from adenine, which occurs in the form of a ''cis''- and a ''trans''-isomer and conjugates. Zeatin was discovered in immature corn kernels from the genus '' Zea''. It promotes growth of lateral buds and when sprayed on meristems stimulates cell division to produce bushier plants. Occurrence Zeatin and its derivatives occur in many plant extracts and are the active ingredient in coconut milk, which causes plant growth. 6-(γ,γ-Dimethylallylamino)purine is a zeatin precursor. Application Zeatin has a variety of effects including: # Promotes callus initiation when combined with auxin, concentration 1 ppm. # Promotes fruit set. Zeatin 100 ppm + GA3 500 ppm + NAA 20 ppm, sprayed at 10th, 25th, 40th day after blossom. # Retards yellowing for vegetables, 20 ppm, sprayed. # Causes auxiliary stems to grow and flower. Zeatin can also be applied to stimulate seed germination and seedling growth. Zeatin has also been shown to promote the resistance of to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeatin
Zeatin is a cytokinin derived from adenine, which occurs in the form of a ''cis''- and a ''trans''-isomer and conjugates. Zeatin was discovered in immature corn kernels from the genus '' Zea''. It promotes growth of lateral buds and when sprayed on meristems stimulates cell division to produce bushier plants. Occurrence Zeatin and its derivatives occur in many plant extracts and are the active ingredient in coconut milk, which causes plant growth. 6-(γ,γ-Dimethylallylamino)purine is a zeatin precursor. Application Zeatin has a variety of effects including: # Promotes callus initiation when combined with auxin, concentration 1 ppm. # Promotes fruit set. Zeatin 100 ppm + GA3 500 ppm + NAA 20 ppm, sprayed at 10th, 25th, 40th day after blossom. # Retards yellowing for vegetables, 20 ppm, sprayed. # Causes auxiliary stems to grow and flower. Zeatin can also be applied to stimulate seed germination and seedling growth. Zeatin has also been shown to promote the resistance of to ... [...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 received a Ph. ... [...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 man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
