Auxin

auxinsrooting hormonerooting hormonesA'''uxinAux/IAA repressorsauxin hormonesAuxin Response Factorsgrowth hormoneIAAplant hormones
Auxins ( plural of auxin ) are a class of plant hormones (or plant growth regulators) with some morphogen-like characteristics.wikipedia
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Indole-3-acetic acid

IAAindole acetic acidindoleacetic acid
Kenneth V. Thimann was the first to isolate one of these phytohormones and determine its chemical structure as indole-3-acetic acid (IAA).
Indole-3-acetic acid (IAA, 3-IAA) is the most common, naturally occurring, plant hormone of the auxin class.

Frits Warmolt Went

F. W. WentFrits W. WentWent
Auxins and their role in plant growth were first described by the Dutch biologist Frits Warmolt Went.
Frits Warmolt Went (May 18, 1903 – May 1, 1990) was a Dutch biologist whose 1928 experiment demonstrated the existence of auxin in plants.

Polar auxin transport

1-N-Naphthylphthalamic acidchemiosmotic model
It is achieved through very complex and well coordinated active transport of auxin molecules from cell to cell throughout the plant body — by the so-called polar auxin transport.
Polar auxin transport is the regulated transport of the plant hormone auxin in plants.

Kenneth V. Thimann

Kenneth ThimannThiman
Kenneth V. Thimann was the first to isolate one of these phytohormones and determine its chemical structure as indole-3-acetic acid (IAA).
He isolated and determined the structure of auxin, the first known plant hormone.

Indole-3-butyric acid

IBAindolebutyric acid
Five naturally occurring (endogenous) auxins in plants include indole-3-acetic acid, 4-chloroindole-3-acetic acid, phenylacetic acid, indole-3-butyric acid, and indole-3-propionic acid. However, most of the knowledge described so far in auxin biology and as described in the article below, apply basically to IAA; the other three endogenous auxins seems to have rather marginal importance for intact plants in natural environments. Alongside endogenous auxins, scientists and manufacturers have developed many synthetic compounds with auxinic activity. In horticulture, auxins, especially NAA and IBA, are commonly applied to stimulate root initiation when rooting cuttings of plants.
IBA is a plant hormone in the auxin family and is an ingredient in many commercial horticultural plant rooting products.

Plant hormone

phytohormoneplant growth regulatorsplant hormones
Auxins ( plural of auxin ) are a class of plant hormones (or plant growth regulators) with some morphogen-like characteristics.
Auxins are compounds that positively influence cell enlargement, bud formation and root initiation.

3-Indolepropionic acid

indole-3-propionic acid
Five naturally occurring (endogenous) auxins in plants include indole-3-acetic acid, 4-chloroindole-3-acetic acid, phenylacetic acid, indole-3-butyric acid, and indole-3-propionic acid. However, most of the knowledge described so far in auxin biology and as described in the article below, apply basically to IAA; the other three endogenous auxins seems to have rather marginal importance for intact plants in natural environments. Alongside endogenous auxins, scientists and manufacturers have developed many synthetic compounds with auxinic activity.
3-Indolepropionic acid (IPA), or indole-3-propionic acid, is a potent neuroprotective antioxidant, plant auxin, and natural product in humans that is being studied for therapeutic use in Alzheimer's disease.

Herbicide

herbicidesherbicidalweed killer
Some synthetic auxins, such as 2,4-D and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), are used also as herbicides.
Synthetic auxins inaugurated the era of organic herbicides. They were discovered in the 1940s after a long study of the plant growth regulator auxin. Synthetic auxins mimic this plant hormone. They have several points of action on the cell membrane, and are effective in the control of dicot plants. 2,4-D is a synthetic auxin herbicide.

Phenylacetic acid

phenylacetatesodium phenylacetatebenzeneacetic acid
Five naturally occurring (endogenous) auxins in plants include indole-3-acetic acid, 4-chloroindole-3-acetic acid, phenylacetic acid, indole-3-butyric acid, and indole-3-propionic acid. However, most of the knowledge described so far in auxin biology and as described in the article below, apply basically to IAA; the other three endogenous auxins seems to have rather marginal importance for intact plants in natural environments. Alongside endogenous auxins, scientists and manufacturers have developed many synthetic compounds with auxinic activity.
Phenylacetic acid has been found to be an active auxin (a type of plant hormone), found predominantly in fruits.

4-Chloroindole-3-acetic acid

4-Cl-IAA
Five naturally occurring (endogenous) auxins in plants include indole-3-acetic acid, 4-chloroindole-3-acetic acid, phenylacetic acid, indole-3-butyric acid, and indole-3-propionic acid. However, most of the knowledge described so far in auxin biology and as described in the article below, apply basically to IAA; the other three endogenous auxins seems to have rather marginal importance for intact plants in natural environments. Alongside endogenous auxins, scientists and manufacturers have developed many synthetic compounds with auxinic activity.
It is a member of the class of compounds known as auxins and a chlorinated derivative of the more common auxin indole-3-acetic acid (IAA).

Phototropism

phototropicphototrophicskototropism
Growth of cells contributes to the plant's size, unevenly localized growth produces bending, turning and directionalization of organs- for example, stems turning toward light sources (phototropism), roots growing in response to gravity (gravitropism), and other tropisms originated because cells on one side grow faster than the cells on the other side of the organ.
The cells on the plant that are farthest from the light have a chemical called auxin that reacts when phototropism occurs.

Coleoptile

coleoptiles
In 1881, Charles Darwin and his son Francis performed experiments on coleoptiles, the sheaths enclosing young leaves in germinating grass seedlings.
A chemical messenger or hormone called auxin moves down the dark side of the shoot and stimulates growth on that side.

Francis Darwin

FrancisFrankDarwin, Francis
In 1881, Charles Darwin and his son Francis performed experiments on coleoptiles, the sheaths enclosing young leaves in germinating grass seedlings.
These observations would later lead to the discovery of auxin.

Bif2 barren inflorescence2

In maize, one example is bif2 barren inflorescence2.
Function. Regulation of auxin transport during axillary Meristem and lateral organ initiation.

Tropism

cell tropismgeotropismmovement
Growth of cells contributes to the plant's size, unevenly localized growth produces bending, turning and directionalization of organs- for example, stems turning toward light sources (phototropism), roots growing in response to gravity (gravitropism), and other tropisms originated because cells on one side grow faster than the cells on the other side of the organ.
In both cases the directional growth is considered to be due to asymmetrical distribution of auxin, a plant growth hormone.

Cutting (plant)

cuttingscuttingcuttings (truncheons)
In horticulture, auxins, especially NAA and IBA, are commonly applied to stimulate root initiation when rooting cuttings of plants.
It was known as early as 1935 that when indolyl-3-acetic acid (IAA), also known as auxin, is applied to the stem of root cuttings, there is an increase the average number of adventitious roots compared to cuttings that are not treated.

Apical dominance

apicalapical growthapical bud
An important principle of plant organization based upon auxin distribution is apical dominance, which means the auxin produced by the apical bud (or growing tip) diffuses (and is transported) downwards and inhibits the development of ulterior lateral bud growth, which would otherwise compete with the apical tip for light and nutrients.
The apical bud produces an auxin (IAA) that inhibits growth of the lateral buds further down on the stem towards the axillary bud.

Cytokinin

cytokinins
For example, the ratio of auxin to cytokinin in certain plant tissues determines initiation of root versus shoot buds.
Cytokinins act in concert with auxin, another plant growth hormone.

2,4,5-Trichlorophenoxyacetic acid

2,4,5-T2,4,5‐T245-T
Some synthetic auxins, such as 2,4-D and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), are used also as herbicides.
2,4,5-Trichlorophenoxyacetic acid (also known as 2,4,5-T), a synthetic auxin, is a chlorophenoxy acetic acid herbicide used to defoliate broad-leafed plants.

Meristem

apical meristemapexshoot apical meristem
Translocation is driven throughout the plant body, primarily from peaks of shoots to peaks of roots (from up to down).
The mechanism of apical dominance is based on auxins, types of plant growth regulators.

Gravitropism

geotropismgeotropicgravitropic
Growth of cells contributes to the plant's size, unevenly localized growth produces bending, turning and directionalization of organs- for example, stems turning toward light sources (phototropism), roots growing in response to gravity (gravitropism), and other tropisms originated because cells on one side grow faster than the cells on the other side of the organ.
Abundant evidence demonstrates that roots bend in response to gravity due to a regulated movement of the plant hormone auxin known as polar auxin transport.

2,4-Dichlorophenoxyacetic acid

2,4-D2, 4-D2,4D
Synthetic auxin analogs include 1-naphthaleneacetic acid, 2,4-dichlorophenoxyacetic acid (2,4-D), and many others.
It acts by mimicking the action of the plant growth hormone auxin, which results in uncontrolled growth and eventually death in susceptible plants.

Phloem

secondary phloemtranslocationcompanion cell
For long distances, relocation occurs via the stream of fluid in phloem vessels, but, for short-distance transport, a unique system of coordinated polar transport directly from cell to cell is exploited.
The hormone auxin, transported by the protein PIN1 is responsible for the growth of those protophloem strands, signaling the final identity of those tissues.

Auxin binding protein

Auxin binding protein
In molecular biology, the auxin binding protein family is a family of proteins which bind auxin.

1-Naphthaleneacetic acid

NAA2-(1-Naphthyl)acetic acidnaphthaleneacetic acids
In horticulture, auxins, especially NAA and IBA, are commonly applied to stimulate root initiation when rooting cuttings of plants. Synthetic auxin analogs include 1-naphthaleneacetic acid, 2,4-dichlorophenoxyacetic acid (2,4-D), and many others.
NAA is a synthetic plant hormone in the auxin family and is an ingredient in many commercial plant rooting horticultural products; it is a rooting agent and used for the vegetative propagation of plants from stem and leaf cutting.