Indoleacetic

Indoleacetic acid, often abbreviated as IAA, is a naturally occurring plant hormone belonging to the auxin class. It plays a crucial role in various aspects of plant growth and development. IAA is synthesized primarily in young leaves, buds, and developing seeds, and then transported to other parts of the plant.

One of its primary functions is the promotion of cell elongation, which is fundamental to plant growth. IAA also influences cell division, differentiation, and the formation of roots. It is involved in tropisms, such as phototropism (growth towards light) and gravitropism (growth in response to gravity), by regulating differential growth rates. Furthermore, IAA plays a role in apical dominance, where the main stem grows more strongly than lateral stems. It also impacts fruit development and abscission, the shedding of leaves, flowers, and fruits.

The concentration of IAA within plant tissues is tightly regulated through synthesis, conjugation, and degradation pathways. Exogenous application of IAA or synthetic auxins can be used in agriculture and horticulture to stimulate rooting of cuttings, promote fruit set, and control weed growth. While IAA is the most abundant and biologically active auxin in plants, other related compounds also exhibit auxin activity.