What is auxin homeostasis?

The regulation of auxin levels by de novo synthesis is one important homeostatic mechanism operating in plant cells, but the levels of IAA can also be attenuated by conjugation (mainly to amino acids and sugars) and by degradation (Normanly, 2010; Rosquete et al., 2012) (Fig. 3C).

What is auxin and its function?

auxin, any of a group of plant hormones that regulate growth, particularly by stimulating cell elongation in stems. In addition to promoting normal growth in plant length, IAA and other auxins influence the growth of stems toward the light (phototropism) and against the force of gravity (geotropism).

What regulates auxin?

The concentration of auxin within a plant cell is regulated both by the rate of its metabolism (i.e., biosynthesis, conjugation/deconjugation, and degradation) and the capacity and rate of transport (in and out of cells and between cellular compartments).

What is the role of auxin in plant physiology?

Auxins promote stem elongation, inhibit growth of lateral buds (maintains apical dominance). They are produced in the stem, buds, and root tips. This produces a curving of the plant stem tip toward the light, a plant movement known as phototropism. Auxin also plays a role in maintaining apical dominance.

What is auxin metabolism?

Figure 1. Principle auxin metabolic pathways in seed plants. Auxin (indole-3-acetic acid, IAA) is synthesized from tryptophan (Trp) via indole-3-pyruvic acid (IPyA), and undergoes irreversible catabolism via oxindole-3-acetic acid (oxIAA).

Where is auxin stored?

When a cutting is taken from a plant, the auxin (mostly IAA) that was stored in the new growing point of the cutting (apical meristem) is transported towards the freshly cut end to begin the process of cell differentiation to initiate root cell development.

What are the 4 functions of Auxins?

Cell growth, cell regeneration, and fruit production are all natural functions that auxins serve for plants.

How does auxin help in Phototropism?

Auxins also play a part in phototropism, an occurrence that involves plants bending or moving away from light. The extra auxin present on the shaded side promotes more cell division and elongation, causing the plant to bend towards the sunlight after this lop-sided growth.

How does auxin transported in the plant?

(a) Auxin (IAA) is transported down to the root tip from the shoot in the vascular cylinder. Here it is redistributed to the root cortex and epidermis, and transported back up the root to the elongation zone, where it regulates the rate of cell elongation.

How are Auxins metabolized in plants?

Principle auxin metabolic pathways in seed plants. Auxin (indole-3-acetic acid, IAA) is synthesized from tryptophan (Trp) via indole-3-pyruvic acid (IPyA), and undergoes irreversible catabolism via oxindole-3-acetic acid (oxIAA).

What is auxin synthesis?

Auxin is synthesized from the amino acid Trp in two chemical steps. The first step is the removal of the amino group by the TAA family of aminotransferases to produce IPA.

What is the function of auxin?

Auxins are an important group of hormones that have multiple functions for plants. Cell growth, cell regeneration, and fruit production are all natural functions that auxins serve for plants. Since their discovery, auxins have been well studied and are now being produced synthetically for a variety of purposes.

How does auxin affect homeostasis of stem cells?

From this zone auxin concentration tends to decrease. Hence, a gradient forms that is thought to be crucial for establishing a proper developmental pattern and maintain stem cell niches. Homeostasis of auxin is also regulated by auxin conjugation.

How does auxin affect the direction of light?

The auxin controls this process by concentrating in the side of the plant away from the sun. This causes changes in the cells, which bend the plant toward the light. This can be seen in the image below. Another important feature which auxin gradients provide many plants is apical dominance.

Is auxin a phytohormone?

IAA is the predominant auxin in plants ( Table 1 ), and is an indispensable phytohormone with a well-documented ability to regulate many aspects of plant development. Synthetic auxin derivatives are still important herbicides; for example, 2,4-dichlorophenoxyacetic acid is one of the world’s most widely used weed-killers.