Receptors and signalling components of plant hormones.

Recent advances in understanding plant hormonal signalling has resulted in the identification of a variety of signalling components including receptor kinases with homology to the bacterial two component system as well as serine/threonine kinases and protein phosphatases. In addition, the existence of MAP kinase pathways in plants indicates a similar role of these signalling cascades in the relay of exogenous signals into the nucleus as has been disclosed in animal cells. The emerging signalling pathways of the plant hormone abscisic acid and ethylene are presented.