Indole-3-butyric acid (1''H''-indole-3-butanoic acid, IBA) is a white to light-yellow crystalline solid, with the molecular formula C₁₂H₁₃NO₂. It melts at 125 °C in atmospheric pressure and decomposes before boiling. IBA is a plant hormone in the auxin family and is an ingredient in many commercial horticultural plant rooting products.

Plant hormone

Since IBA is not completely soluble in water, it is typically dissolved in 75% or purer alcohol for use in plant rooting, making a solution of between 10,000 and 50,000 ppm. This alcohol solution is then diluted with

distilled water Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, di ...

to the desired

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', '' number concentration'', ...

. IBA is also available as a

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

, which is soluble in water. The solution should be kept in a cool, dark place for best results. This compound had been thought to be strictly synthetic; however, it was reported that the compound was isolated from leaves and seeds of maize and other species. In maize IBA has been shown to be synthesized in vivo using IAA and other compounds as precursors. This chemical may also be extracted from any of the Salix (

Willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...

) genus.

Plant tissue culture

In plant tissue culture IBA and other auxins are used to initiate root formation in vitro in a procedure called

micropropagation Micropropagation or tissue culture is the practice of rapidly multiplying plant stock material to produce many progeny plants, using modern plant tissue culture methods. Micropropagation is used to multiply a wide variety of plants, such as th ...

. Micropropagation of plants is the process of using small samples of plants called explants and causing them to undergo growth of differentiated or undifferentiated cells. In connection with

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 le ...

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 ...

, auxins like IBA can be used to cause the formation of masses of undifferentiated cells called

callus A callus is an area of thickened and sometimes hardened skin that forms as a response to repeated friction, pressure, or other irritation. Since repeated contact is required, calluses are most often found on the feet and hands, but they may o ...

. Callus formation is often used as a first step process in micropropagation where the callus cells are then caused to form other tissues such as roots by exposing them to certain hormones like auxins that produce roots. The process of callus to root formation is called indirect organogenesis whereas if roots are formed from the explant directly it is called direct organogenesis. In a study of '' Camellia sinensis'', the effect of three different auxins, IBA, IAA and

NAA NAA or Naa may refer to: People * Naa Ashorkor (born 1988), Ghanaian actress and radio/ TV broadcaster * Naa Govindasamy (1946–1999), Singaporean Tamil-language writer and computer font developer * Naa Someswara, Indian science writer and T ...

were examined to determine the relative effect of each auxin on root formation. According to the result for the species, IBA was shown to produce a higher yield of roots compared to the other auxins. The effect of IBA is in concurrence with other studies where IBA is the most commonly used auxin for root formation.

Mechanism

Although the exact method of how IBA works is still largely unknown, genetic evidence has been found that suggests that IBA may be converted into IAA through a similar process to

β-oxidation In biochemistry and metabolism, beta-oxidation is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA, which enters the citric acid cycl ...

fatty acids In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an B ...

. The conversion of IBA to IAA then suggests that IBA works as a storage sink for IAA in plants. There is other evidence that suggests that IBA is not converted to IAA but acts as an auxin on its own.

References

External links

{{commons category inline, Indolebutyric acid Auxins Indoles Carboxylic acids