Types of Auxin

The various types of auxins are explained below:

Indole-3-Acetic Acid (IAA)

• Naturally occurring auxin in plants.
• Regulates cell elongation, root initiation, and apical dominance.
• It is synthesized in young leaves, apical buds, and developing seeds.
• Plays a central role in tropic responses like phototropism and gravitropism and is involved in vascular tissue differentiation and stress responses.
• It also functions as a signaling molecule in various developmental processes and can be transported polarly within plants to coordinate growth.

2,4-Dichlorophenoxyacetic Acid (2,4-D)

• It is synthetic auxin widely used in herbicides and plant growth regulators.
• It mimics the effects of natural auxins and induce uncontrolled growth in susceptible plants.
• Effective in controlling broadleaf weeds without harming grasses in agriculture and is used to regulate plant growth and development in forestry and horticulture.
• It can disrupt hormonal balance in plants at high concentrations.

Also Read: Coordination in Plants

Naphthaleneacetic Acid (NAA)

• It is a synthetic auxin commonly used in agriculture and horticulture.
• Promotes root initiation and development, especially in stem cuttings.
• Helps prevent premature fruit drop and enhances fruit set in some crops.
• Used to induce rooting in difficult-to-root plant species and in tissue culture.
• Can be applied as a foliar spray or as a rooting hormone in rooting media.

Indole-3-Butyric Acid (IBA)

• It is a synthetic auxin with rooting properties similar to NAA.
• Used to stimulate root growth in stem cuttings and to promote root development.
• It is also used in horticulture for propagating plants from cuttings.
• Can be applied as a powder, liquid, or gel formulation for rooting.

1-Naphthaleneacetic Acid (1-NAA)

• It is a synthetic auxin structurally similar to NAA.
• Utilized in plant tissue culture for callus induction and somatic embryogenesis.
• Effective in promoting root formation in plant tissue cultures.
• It is also used in combination with cytokinins for shoot proliferation and regeneration.

Also Read: Movement Due to Growth in Plants – Tropical and Nastic Movements

Auxin is a plant hormone. Auxin hormone function is to control growth and developmental processes in plants, including cell expansion, root initiation, and bud and flower growth. Auxin, discovered by Charles Darwin and his son Francis, was first isolated from human urine.

Auxin plays a key role in plant adaptation to the environment, and its functions are associated with signal transduction, transport, homeostasis, and biosynthesis pathways. In this article, we will study the auxin, its types, mechanism of action, and functions in detail.