Auxin Plant Hormone

Definition:

The word ‘auxin’ is derived from the Greek word ‘auxin’, which means growth. Auxins were first separated from human urine. The term ‘auxin’ is used in indole-3-acetic acid (IAA), as well as in other natural and synthetic compounds that have specific properties that control growth. Auxins are usually produced by growing apices of stems and roots, from where they migrate to their action areas.

Auxin is a powerful growth hormone produced by plants naturally. Auxins are found in the trunk and root systems of plants to promote cell division, stem, and root growth. It drastically alters a plant’s orientation by promoting cell division on one side of the plant, responding to sunlight and gravity.

Structure

Auxin molecules are commonly found in the amino acid tryptophan. These amino acids have a six-sided carbon ring, attached to a five-sided carbon ring. The difference between auxin molecule and tryptophan is based on the ring attachment.

To form the normal IAA auxin molecule, two enzymes are required for activation of tryptophan first. Aminotransferase releases nitrogen and hydrogen into a side series connected to a 5-sided ring. The decarboxylase enzyme then removes the carboxyl group, leaving COOH. A chloride ion is attached to a six-sided ring and the IAA is born. Many auxins are found in this molecule.

Function

Some of the auxin functions in plants are given below:

• Auxin hormones have a variety of uses in plants. Auxiliary molecules are found in all plant tissues. They are mainly focused on the meristems, which are the centers of growth.
• Growth centers release auxin molecules and are distributed near the roots. In this way, plants can coordinate their size and growth, and development in different tissues based on auxin gradient.
• Auxin affects many cellular processes at different cellular levels. Auxin cells affect cytoplasmic circulation such as fluid flow within a cell and even the activity of various enzymes.
• Auxins directly control the growth, and proliferation of cells within a plant. The gradient of auxins directly affects flower initiation, fruit development, and even the formation of tubers and bulbs.
• The level of auxins also affects daily phototropism, also helping the plant to follow the sun and get more energy from it.
• Apical dominance is another feature of auxin gradients in many plants. Build when one meristem grows faster and more efficiently. Auxin extracted from this type of meristem prevents new shoots from growing under it. When the stem is cut, many new shoots will appear under it, and when the auxin gradient is disturbed, the system must create a new leading shoot. The main life-saving effect of auxin in plants is to promote cell proliferation in the shoot, which can be seen in phototropic wrapping.

The Physiological Role of Auxins

Some of the important physiological roles of auxins are:

• Apical rule – It is a growing apical bud, which prevents the growth of lateral buds.
• Root initiation – Auxins help initiate germination after stem cutting.
• Blossoms – Auxins help promote pineapple blossoms.
• Abscission – Auxins promote the removal of old leaves and fruit.
• Auxins help in cell division.

Use of Auxins

Auxins form parthenocarpy, in tomatoes. They are widely used as herbicides such as 2, 4-D, which are widely used to kill dicotyledonous weeds. But it does not affect mature monocotyledonous plants. Auxin is also used to weed weeds that growers have with large gardens. Auxin regulates xylem differentiation and also helps cell division.

Conclusion

After obtaining complete information about auxin, what the auxin is, its composition, function, and use, and after discussing auxin body functions, it is clear that auxin is not considered a hormone, as its properties are not compatible with auxin. definition of the hormone. There are two types of auxin, one naturally occurring in plants and the other man-made. Auxins strongly support cell proliferation on the dark side of the plant compared to the other side of the plant.

Plants need sunlight, water, oxygen, minerals to grow and develop. These are external factors. Apart from this, there are certain internal factors that control plant growth and development. These are called plant hormones or “Phytohormones”. Plant hormones are a combination of chemicals that are present at very low concentrations in plants. They are derived from indole (auxins), terpenes (Gibberellins), adenine (Cytokinins), carotenoids (Abscisic acid), and gases (Ethylene). These hormones are produced in almost every part of the plant and are transferred to various parts of the plant. They may act in harmony or individually. The roles of different hormones can complement or contradict each other. Hormones play an important role in processes such as vernalization, phototropism, seed germination, sleep, etc., and external features. Synthetic plant hormones are used in addition to controlled plant production. Charles Darwin first observed phototropism in canary grass coleoptiles and F.W. He first took auxin alone from oat plant coleoptiles.

Auxin Growth Hormone

Auxins are a powerful growth hormone produced naturally by plants. They are found in the tips of the shoot and roots and promote cell division, stem growth, and roots. They can also adversely affect plant pathways by promoting cell division on one side of the plant by responding to sunlight and gravity.

Auxin for root growth

Auxin is essential for the regulation of root system architecture by controlling primary root elongation and lateral root (LR) formation. Exogenous auxin has been reported to inhibit primary root elongation and promote the formation of LRs.

Also read: Important Topic of Biology: Gibberellin

FAQs:

Why Is Auxin Not a Hormone?

Auxin is not a hormone because it may be active at low concentrations and can be transported but is not produced in specific tissues. And it is so pleiotropic that it can be considered a hormone. In fact, auxin appears to be a signal that triggers a set system instead of a specific hormone.

What Do You Mean by Natural Auxin?

Generally, there are two types of natural and synthetic hormones. Natural auxins are those that are present in the plant naturally. Some examples of natural auxins are IAA (Indole 3 acetic acid) and IBA (indole 3 butyric acid). Synthetic Auxin is known as synthetic auxins. Some examples of compressed auxins are 2,4-D.

Is Auxin Toxic to Humans?

Indole-3-acetic acid is a major auxin produced by plants and plays a key role in plant growth and development. The same hormone is present in humans, where it is considered a uremic toxin derived from tryptophan metabolism. It is therefore not a toxic substance in the human body.