Auxins are a class of plant hormones responsible for various aspects of plant growth.

Indole-3-acetic acid (IAA) is the main auxin in most plants.

Typically, they affect cell enlargement and elongation.

They also allow the plant to react to sunlight and gravity, known as phototropism and geotropism, respectively.

In many plants auxins are responsible for establishing the apical meristem, and establish the growth direction of the plant.

IAA is synthesized from tryptophan or indole primarily in leaf primordia and young leaves, and in developing seeds.

IAA transport is cell to cell. Transport to the root probably also involves the phloem.

IAA moves in one direction only (downward).

Such downward movement in shoots is said to be basipetal movement, and in roots it is acropetal.

Facilitate flowering in plants

Communication Division

Used in the process of plant propagation.

 Used by gardeners to keep lawns free from weeds.

Involved in the initiation of roots in stem cuttings.

Prevention of dropping of leaves and fruits at early stages.

 Regulate xylem differentiation and assists in cell division.

Auxins are widely used as herbicides to kill dicot weeds

Used to produce fruit without preceding fertilization.

Promote natural detachment (abscission) of older leaves and fruits.

Apical dominance may occur in which the growth of lateral buds is inhibited by the growth of apical buds. In such cases, the shoot caps may be removed.

These are produced by the apex of root and shoot.

1- The speed and amount of biosynthesis of auxins in the apical and meristematic region in the plant.

2- The amount and the speed of translocation of auxins to the certain place in the plant tissues.

3- The quality and the activity of the enzymes could analyze IAA.

4- The activity of detoxification reactions in the plant cell tissues.