Auxins
Auxins are plant growth hormones due to their ability to stimulate differential growth in response to light stimuli. They are the phytohormones that play the most important role in the development of plants. Four natural auxins synthesized by plants have been described: IAA, indole-3-butyric acid (IBA), 4-chloroindole-3-acetic acid (4-Cl-IAA), and phenylacetic acid (PAA). In vitro tests have made it possible to determine that IAA is one of the main auxins involved in plant development.
Indole-3-acetic acid (IAA)
IAA is the main native auxin of higher plants. IAA is involved in plant growth and development, mainly in a series of physiological processes that include cell elongation and division, tissue differentiation, phototropism, gravitropism, and defensive responses, highlighting an important role in xylem formation. and the root.
IAA biosynthesis is not limited to higher plants. Organisms such as bacteria, fungi, and algae are capable of synthesizing IAA, which can affect plant growth and development. In bacteria, the production of IAA is a relevant capacity, both for PGPBs and for phytopathogenic bacteria. Higher plants exude, among other components, the amino acid tryptophan, which is the main precursor for the biosynthesis of microbial IAA.
Indole-3-butyric acid (IBA)
Indole-3-butyric acid (IBA) is a promoter for the growth of the lateral roots of plants, the dose and time of application are critical to stimulate rooting. The most abundant type of auxin in nature is indole acid -3-acetic acid (AIA), since indole-3-butyric acid (IBA) is found in smaller amounts in plants.
Among the synthetic hormones is IBA, a growth regulator that promotes and accelerates the formation of adventitious roots in plants. It is frequently used for the propagation of cuttings or cuttings and layers. This type of growth hormone has shown a positive effect on plant development by stimulating the formation of lateral roots. IBA was initially used as a root growth promoter for asexual propagation of ornamental and fruit plants. However, currently some studies have shown that IBA provides direct benefits in the growth of plants that are sown by seed: it promotes the absorption of nutrients, accelerates growth, favors root formation and optimizes metabolic functions.
4-chloroindole-3-acetic acid (4-Cl- AIA)
It is a compound belonging to the organic acid groups with Auxinic effect, that is, with functions to promote cell division and in some cases the cellular elongation of its tissues, in the same way as in the previous cases, it is biosynthesized in the apical buds of the plant in the coleoptile. and in young tissues such as leaves and shoots that are actually producing these compounds, it is a natural compound that is produced regularly in plants of the legume family such as beans, broad beans, lentils and peas. It is a very powerful auxin, however its spectrum of action in a group of plants is quite small and very specific to the legumes described above, its production spectrum only occurs in legumes, they are produced in apical meristems in coleoptile apices (pods) in This type of seed is produced in greater quantity.
It is produced naturally by plants, however, it can be obtained through chemical synthesis, it is one of the most stable and efficient auxins, however its concentration doses are low and sometimes it can produce when it is a synthetic source some phytotoxicities that could put our crop at risk
Phenylacetic acid
Phenylacetic acid is an active auxin (a type of phytohormone predominant in fruits); however, its effect is milder than that of indole-3-acetic acid (another auxin). Phenylacetic acid is an active auxin (a type of phytohormone predominant in fruits); however, its effect is milder than that of indole-3-acetic acid (another auxin). Phenylacetic acid is an active auxin (a type of phytohormone predominant in fruits); however, its effect is milder than that of indole-3-acetic acid (another auxin). Phenylacetic acid is an active auxin (a type of phytohormone predominant in fruits); however, its effect is milder than that of indole-3-acetic acid (another auxin).
Phenylacetic acid is widely distributed in vascular and non-vascular plants and is recognized as a natural phytohormone or auxin, that is, a hormone that regulates plant growth. It exerts a positive effect on the growth and development of plants. It is usually located on the shoots of plants.