ABSTRACT
Hormones are chemical messengers that coordinate the cell functions of multicellular organisms. Animals produce many chemical hormones, each of which generally targets a few cells and triggers a specific response. However, plant hormones (phytohormones) are less numerous, usually affect most, if not all cells, and trigger various responses. Moreover, the accumulation and effects of each phytohormone are modulated by the influences of the environment and development as well as by the activities of other phytohormones. Unraveling complex hormonal action networks and signaling pathways in plants is underway; several hormonal receptors have only recently been identified, and many signaling components are still unidentified. This chapter gives a brief introduction to plant hormones, their functions throughout the life cycle of plants, their cell effects, signaling pathways, as well as their interactions with other hormones.
