hormonesauxins

Auxins are a class of plant hormones that play a crucial role in plant growth and development. The most well-known and abundant auxin is indole-3-acetic acid (IAA). Auxins are primarily synthesized in the shoot apical meristems, young leaves, and developing seeds. They are then transported throughout the plant, typically in a polar fashion, moving from the apical to the basal ends of tissues.

The functions of auxins are diverse and essential for plant life. They are instrumental in cell elongation, a process vital for stem and root growth. Auxins also influence cell division and differentiation. A key role of auxins is in apical dominance, where the terminal bud inhibits the growth of lateral buds, leading to a single main stem. They are involved in phototropism, the bending of plants towards a light source, by promoting cell elongation on the shaded side. Similarly, auxins contribute to gravitropism, influencing root growth downwards and shoot growth upwards in response to gravity. Furthermore, auxins are implicated in fruit development and abscission, the shedding of leaves and fruits. Their application in agriculture and horticulture is widespread, used as rooting hormones to stimulate root formation in cuttings and as herbicides at high concentrations.