Chapter 18. Plant Hormones

BOGATEK, R.; GNIAZDOWSKA, A.; SAMPIETRO, D. A.; SOBERÓN, J. R.

Plant Biochemistry

Studium Press, LLC

Lugar: Houston, USA; Año: 2009; p. 441 - 471

The synchronic growth, development and function of a plant, as a multicellular organism is not possible without efficient communication among cells, tissues and organs. Regulation and coordination of plant metabolism and morphogenesis depends on chemical messengers called phytohormones. A phytohormone is often defined as an organic compound that is produced in one plant part and exerts its action (at very low concentrations) in other plant parts. Plant hormones are often active at concentrations as low as 1 µM. However, activity of a phytohormone in a given tissue depends on its relative concentration more than in its absolute one. Hence, delicate balances among the endogenous phytohormones define their effects on growth rate and developmental events. Some known phytohormones are: Abscisic acid, Gibberellins, Auxins, Cytokinins, Ethylene and Iasmonic acid. Constant monitoring of abiotic (e.g. light, oxygen, water, salt, temperature and nutrients) and biotic factors (e.g. neighboring plants or pathogenic microorganisms/hervibores) by independent perception and transduction pathways is required for plant growth and development. Phytohormones function as key signalling molecules in the these pathways regulating plant shape, seed growth, time of flowering, flower sex, senescence of leaves and fruits, fruit development and ripening, plant longevity and even plant death.