This article is about physical movement in organisms. For infection specificity of pathogens, see Host tropism and Tissue tropism. For the novel, see Tropisms.
In biology, a tropism is a phenomenon indicating the growth or turning movement of an organism, usually a plant, in response to an environmental stimulus.[1] In tropisms, this response is dependent on the direction of the stimulus (as opposed to nastic movements, which are non-directional responses). Tropisms are usually named for the stimulus involved; for example, a phototropism is a movement to the light source, and an anemotropism is the response and adaptation of plants to the wind.[2]
Tropisms occur in three sequential steps. First, there is a sensation to a stimulus. Next, signal transduction occurs. And finally, the directional growth response occurs.
Tropisms can be regarded by behaviorists as taxis (directional response) or kinesis (non-directional response).
The Cholodny–Went model, proposed in 1927, is an early model describing tropism in emerging shoots of monocotyledons, including the tendencies for the stalk to grow towards light (phototropism) and the roots to grow downward (gravitropism). In both cases, the directional growth is considered to be due to asymmetrical distribution of auxin, a plant growth hormone.[3]
The term "tropism" (from Ancient Greekτρόπος (trópos) 'a turn, way, manner, style, etc.', and -ism) is also used in unrelated contexts. Viruses and other pathogens affect what is called "host tropism", "tissue tropism", or "cell tropism"; in which case tropism refers to the way in which different viruses/pathogens have evolved to preferentially target specific host species, specific tissue, or specific cell types within those species. In English, the word tropism is also used to indicate an action done without cognitive thought: However, "tropism" in this sense has a proper, although non-scientific, meaning as an innate tendency, natural inclination, or propensity to act in a certain manner towards a certain stimulus.
Tropisms can be distinguished according to the orientation with respect to the direction of the stimulus. They can commonly be either positive (towards the stimulus) or negative (away from it).[4] Both of these are orthotropic,[5] and can be contrasted with tropisms that are diatropic (perpendicular to the stimulus) or plagiotropic (at an oblique angle).[6]
According to the type of stimulus, tropisms can be:
Example of gravitropism in the remains of a cellar of a Roman villa in the Archeologic Park in Baia, Italy
Aerotropism: the growth of plants towards or away from a source of wind[7]
Exotropism: continuation of growth "outward," i.e. in the previously established direction[10]
Gravitropism (sometimes referred to as geotropism): is movement or growth in response to gravity[4]
Apogeotropism: negative geotropism
Heliotropism: the diurnal motion or seasonal motion of plant parts in response to the direction of the Sun, (e.g. the sunflower)
Apheliotropism: negative heliotropism
Hydrotropism: movement or growth in response to water; in plants, the root cap senses differences in water moisture in the soil, and signals cellular changes that cause the root to curve towards the area of higher moisture[11]
Prohydrotropism: positive hydrotropism
Hygrotropism: movement or growth in response to moisture or humidity[citation needed]
Magnetotropism: movement or growth in response to magnetic fields
The dictionary definition of tropism at Wiktionary
Media related to Tropism at Wikimedia Commons
February 16, 2024
tropism, this, article, about, physical, movement, organisms, infection, specificity, pathogens, host, tropism, tissue, tropism, novel, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable. This article is about physical movement in organisms For infection specificity of pathogens see Host tropism and Tissue tropism For the novel see Tropisms This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Tropism news newspapers books scholar JSTOR September 2012 Learn how and when to remove this template message In biology a tropism is a phenomenon indicating the growth or turning movement of an organism usually a plant in response to an environmental stimulus 1 In tropisms this response is dependent on the direction of the stimulus as opposed to nastic movements which are non directional responses Tropisms are usually named for the stimulus involved for example a phototropism is a movement to the light source and an anemotropism is the response and adaptation of plants to the wind 2 Daisies Bellis perennis facing the Sun after opening in the morning showing heliotropismPhycomyces a fungus exhibiting phototropismTropisms occur in three sequential steps First there is a sensation to a stimulus Next signal transduction occurs And finally the directional growth response occurs Tropisms can be regarded by behaviorists as taxis directional response or kinesis non directional response The Cholodny Went model proposed in 1927 is an early model describing tropism in emerging shoots of monocotyledons including the tendencies for the stalk to grow towards light phototropism and the roots to grow downward gravitropism In both cases the directional growth is considered to be due to asymmetrical distribution of auxin a plant growth hormone 3 The term tropism from Ancient Greek tropos tropos a turn way manner style etc and ism is also used in unrelated contexts Viruses and other pathogens affect what is called host tropism tissue tropism or cell tropism in which case tropism refers to the way in which different viruses pathogens have evolved to preferentially target specific host species specific tissue or specific cell types within those species In English the word tropism is also used to indicate an action done without cognitive thought However tropism in this sense has a proper although non scientific meaning as an innate tendency natural inclination or propensity to act in a certain manner towards a certain stimulus Contents 1 Types 2 See also 3 References 4 External linksTypes editTropisms can be distinguished according to the orientation with respect to the direction of the stimulus They can commonly be either positive towards the stimulus or negative away from it 4 Both of these are orthotropic 5 and can be contrasted with tropisms that are diatropic perpendicular to the stimulus or plagiotropic at an oblique angle 6 According to the type of stimulus tropisms can be nbsp Example of gravitropism in the remains of a cellar of a Roman villa in the Archeologic Park in Baia ItalyAerotropism the growth of plants towards or away from a source of wind 7 Chemotropism the movement or growth in response to chemicals 8 Electrotropism or galvanotropism the movement or growth in response to an electric field 6 9 Exotropism continuation of growth outward i e in the previously established direction 10 Gravitropism sometimes referred to as geotropism is movement or growth in response to gravity 4 Apogeotropism negative geotropism Heliotropism the diurnal motion or seasonal motion of plant parts in response to the direction of the Sun e g the sunflower Apheliotropism negative heliotropism Hydrotropism movement or growth in response to water in plants the root cap senses differences in water moisture in the soil and signals cellular changes that cause the root to curve towards the area of higher moisture 11 Prohydrotropism positive hydrotropism Hygrotropism movement or growth in response to moisture or humidity citation needed Magnetotropism movement or growth in response to magnetic fields Phototropism movement or growth in response to lights or colors of light Aphototropism negative phototropism Skototropism negative phototropism of vines Selenotropism motion of plant parts in response to the direction of the Moon 12 Thermotropism movement or growth in response to temperature Thigmotropism movement or growth in response to touch or contact Traumatotropism orientation deviation after suffering a wounding 6 13 See also editChemotaxis Rapid plant movement Nutation botany References edit Darwin Charles 1900 The Power of Movement in Plants Appleton Taki Tarek Siddiki 2023 09 30 Anemotropism Plants Response amp Adaptation To Wind GreenLeen Com Retrieved 2023 09 30 Haga Ken Takano Makoto Neumann Ralf Iino Moritoshi January 1 2005 The Rice COLEOPTILE PHOTOTROPISM1 Gene Encoding an Ortholog of Arabidopsis NPH3 Is Required for Phototropism of Coleoptiles and Lateral Translocation of Auxin W Plant Cell 17 1 103 15 doi 10 1105 tpc 104 028357 PMC 544493 PMID 15598797 a b Plant tropisms Plant and animal hormones BBC Bitesize Retrieved 22 April 2022 orthotropic Oxford English Dictionary Online ed Oxford University Press Retrieved 2 July 2022 Subscription or participating institution membership required a b c Tropism biology Encyclopaedia Britannica Online 2003 Retrieved 2 July 2022 Aerotropism Merriam Webster Retrieved 22 April 2022 Chemotropism Merriam Webster Retrieved 22 April 2022 Galvanonism Merriam Webster Retrieved 22 April 2022 Exotropism Merriam Webster Retrieved 22 April 2022 Cassab Gladys I Eapen Delfeena Campos Maria Eugenia 2013 01 01 Root hydrotropism An update American Journal of Botany 100 1 14 24 doi 10 3732 ajb 1200306 ISSN 0002 9122 PMID 23258371 Selenotropism definition and meaning Collins Dictionary Retrieved 24 April 2022 Traumatropism Merriam Webster Retrieved 24 April 2022 External links edit nbsp The dictionary definition of tropism at Wiktionary nbsp Media related to Tropism at Wikimedia Commons Retrieved from https en wikipedia org w index php title Tropism amp oldid 1202122226, wikipedia, wiki, book, books, library,
