Auxin Function

Auxins are a group of plant hormones (or plant growth regulators) that resemble morphogens. Auxins are important for plant body development and play a critical role in the coordination of various growth and behavioural processes in plant life cycles. Auxins and their role in plant growth were initially described in the 1920s by Dutch biologist Frits Warmolt Went. Kenneth V. Thimann was the first to isolate and characterise one of these phytohormones, identifying it as indole-3-acetic acid (IAA). In 1937, Went and Thimann co-authored Phytohormones, a treatise on plant hormones.

Overview

The discovery of auxins was the first of the primary plant hormones. Their name comes from the Greek word v (auxein, which means “to grow/increase”). Auxin can be found in all regions of a plant, although in varying amounts. Because the concentration in each site contains important developmental information, it is tightly regulated by metabolism and transport. As a result, auxin produces “patterns” of auxin concentration maxima and minima in the plant body, which regulate the development of individual cells and, eventually, the entire plant.

Discovery of Auxin

Charles Darwin

Charles Darwin and his son Francis conducted research on coleoptiles, the sheaths that enclose immature leaves in grass seedlings, in 1881. The coleoptile was exposed to light from a single direction in the experiment, and it was found that it bent towards the light. [8] The Darwins discovered that light is detected by the coleoptile tip, but that bending occurs in the hypocotyl, by covering various portions of the coleoptiles with a light-impermeable opaque cap.

Peter Boysen Jensen

Peter Boysen Jensen, a Danish scientist, demonstrated in 1910 that the phototropic stimulation in the oat coleoptile could be propagated through an incision. [10] In 1911 and 1913, these tests were expanded and published in greater detail. [11][12] He discovered that the tip could be cut off and reattached, and that one-sided lighting could still induce a positive phototropic curvature in the coleoptile’s basal section.

Hormonal Activity

Auxins and plant development at all stages, from the cellular level to the organ level and finally to the entire plant.

When auxin interacts with a plant cell, it causes significant changes in gene expression, with many genes being up- or down-regulated. The particular methods by which this occurs are still being investigated, but at least two auxin signalling routes have been identified. 

Synthetic Auxins

Many substances with notable auxin action have been produced during auxin biology study. In agronomy, many of them were discovered to offer economic potential for human-controlled plant growth and development.

Effects

Auxins are poisonous to plants in high doses; dicots are the most toxic, whereas monocots are the least toxic.

Phototropism, geotropism, hydrotropism, and other developmental processes are all aided by Auxin. Auxin distribution is uneven due to environmental cues such as unidirectional light or gravity force, and auxin affects the form and shape of the plant body, the direction and strength of all organs’ growth, and their mutual interaction in general.

Conclusion

Auxins are a group of plant hormones (also known as plant growth regulators) that have morphogen-like properties. Auxins are important for plant body development and play a critical role in the coordination of various growth and behavioural processes in plant life cycles.

Auxin encourages plant cell development and elongation. Auxin changes the plant wall flexibility during the elongation phase, making it easier for the plant to grow upwards. Auxin also has an impact on root development.