What is the role of plant hormones in regulating growth and development?

Plant hormones play a critical role in regulating growth and development of plants. There are five major types of plant hormones: auxins, cytokinins, gibberellins, abscisic acid, and ethylene. Each hormone has a specific function in regulating plant growth and development, and they often work together to produce a particular effect.

Auxins, for example, are involved in cell elongation, apical dominance, and root initiation. Cytokinins promote cell division and delay senescence. Gibberellins stimulate stem elongation and can break seed dormancy. Abscisic acid promotes seed dormancy and helps plants withstand drought stress. Ethylene is involved in fruit ripening, leaf senescence, and abscission.

The effects of plant hormones are mediated by specific receptors located on the surface or inside the cells of target tissues. The receptors activate signaling pathways that lead to changes in gene expression and other cellular processes. The balance and interaction between different plant hormones are critical for normal plant growth and development, and any disruption of this balance can lead to abnormal growth, developmental defects, or even death.