What is Auxin Hormone in Biology?

What is Auxin Hormone in Biology? - One of  the hormones that affect plant growth and development is auxin. How can the hormone Auxin be found? What is the main function of this auxin hormone?. Want know more about the auxin hormone? The following is the explanation of Auxin Hormone.

History of the Auxin Hormone

Auxin Experiments Frist W. Went

     Auxin hormone was first discovered from the experiments of Charles Darwin in 1881 with his son, Francis Darwin. Based on the experiments they have done, they can conclude that there is something that affects plant growth. These substances come from the tip of the stem (apical shoots) which are then flowed to the bottom through the side that is not exposed to light.

     In 1928, a plant anatomist, Frits W. Went from the Netherlands. Discovered that there are chemical substances that affect growth at the tips of plant stems. Went cuts the ends of the stems of oat plants and puts them in the jelly layer for about an hour. Next, the jelly pieces are placed on the ends of the stems of plants that have been cut. After a few hours, the stems grow. The experiment showed that there were chemical compounds which were absorbed from the cuttings of the rods into the jelly. Therefore, when jelly is placed on the cut ends of the stem, the chemical compounds cause growth. The chemical compound is then called Auxin.

Function of the Auxin Hormone

Auxin Hormone

     In general, the auxin hormone is continuously produced at the tips of young stems and leaves. The compound will be distributed in one direction (to the bottom of the plant). Naturally, auxin which was first isolated in plants is called indolasetat acid (AIA) or indolacetic acid (IAA). Here are some functions of the auxin hormone in plants:

1. Affects apical growth (tip of the stem). As long as the auxin hormone is still being produced, shoot growth (apical buds) will continue, while lateral buds will not. This condition is known as apical dominance.
2. Influence the development of fruit. At the time of seed development, the seeds secrete the hormone auxin which is distributed to the flowers. So that it can stimulate fruit growth in plants. Spraying the auxin hormone in flowers allows fruit to develop. Although the interest had not previously been pollinated. The fruit produced in the form of fruit without seeds.
3. Reducing the growth of lateral branches. The growth of the lateral branch is inhibited because there is an auxin hormone which is channeled from the top of the stem to the bottom and does not spread to the side. As a result, the growth of lateral branches becomes slow. To get a lot of branch growth, the shoots must be cut off.
4. Inhibiting fruit loss and leaf fall. In old leaves and fruit, the production of the auxin hormone is inhibited by the presence of a special coating called the abscess layer. The existence of these layers on the leaf stalks and fruit stalks causes the leaves and fruit can not survive sticking to the stem so that the leaves and fruit easily loss or fall.
5. Stimulate the formation of wild roots. Wild roots are roots that grow on the leaves and stems. We can stimulate the growth of plant roots by cutting leaves or stems. Next, the piece is given a solution containing synthetic auxin hormone. In this way, we can propagate plants vegetatively (vegetative reproduction) through leaf or stem pieces

Summary : the main function of the auxin hormone is to stimulate stem elongation, affect root growth, differentiation and branching, fruit development, apical dominance, phototropism, and gravitropism.

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