What is an Auxin, it’s types and functions in plants

You may have been searching online for the meaning of auxins, it’s types and functions or roles in plants. We are at your service to give a friendly and simplified tutorial on auxins. Are you ready for the tutorials? ok, let’s go there.

Auxins are plant hormones which is found at the apical part of the plant and stimulates stem elongation inhibit growth of lateral applicable maintains apical dominance e t c. They are produced in the stem, buds and root tips.

Examples includes indole-3-acetic acid(IAA). Auxin is a plant hormone produced in the stem tip that promotes cell elongation. They move to the darker side of the plant causing the cells there to grow larger than corresponding cells on the lighter side of the plant. This produces a curving of the plants stem tip towards the light, a plant movement known as phototropism.

It also plays a role in maintaining apical dominance as we have denoted before. Most plants have lateral or you can also call it auxiliary boats located at the nodes. (Where leaves attached to the stem).

Buds are embryonic meristem. They were the first of the major plant hormone to be discovered. They derived their name from the greek word auxein which means to grow or increase. Auxin namely IAA is present in all parts of the plant although in very different concentrations. It is subject to tight regulation through both mechanisms and transport.

Types of auxins

There are 5 normally occurring endogenous auxins in plants which

. Indole-3-Acetic4-chloroindole-3-aceticphenylacetic acidIndole-3-butyric acidIndole-3-propionic acid.

synthetic auxins includes

1-nephthaleinacetic acid,2,2,4-dichlorophenoxyacetic acid, (2,4-D),2,4-dichlorophenoxyacetic acid.


Some Auxin such as 2,4-D and 2,4,5-triphenoxyacetic acid 2,4,5-T are used as herbicides. Broad leaf plants or dicot such as dandelion are much more susceptible to auxins than narrow leaves monocots.

Auxin hormonal activity

It helps development at all levels in plants, from the cellular level through organs and ultimate the whole plant

Molecular mechanism

When a plant cell comes in contact with Auxin, it causes dramatic changes in gene expression. With many genes up or down regulated, the precise mechanism by which this occurs are still an area of active research.


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