Phytochromes control photomorphogenesis by differentially regulated, interacting signaling pathways in higher plants.
In this review the kinetic properties of both phytochrome A and B measured by in vivo spectroscopy in Arabidopsis are described. Inactivation of phyA is mediated by destruction and that of phyB by fast dark reversion. Recent observations, describing a complex interaction network of various phytochromes and cryptochromes, are also discussed. The review describes recent analysis of light-dependent nuclear translocation of phytochromes and genetic and molecular dissection of phyA- and phyB-mediated signal transduction. After nuclear transport, both phyA- and phyB-mediated signal transduction probably include the formation of light-dependent transcriptional complexes. Although this hypothesis is quite attractive and probably true for some responses, it cannot account for the complex network of phyA-mediated signaling and the interaction with the circadian clock. In addition, the biological function of phytochromes localized in the cytosol remains to be elucidated.
Nagy
Ferenc
F
Institute of Plant Biology, Biological Research Center, H-6701 Szeged, Hungary. nagyf@nucleus.szbk.u-szeged.hu
Schäfer
Eberhard
E
D009024:Morphogenesis; D010834:Phytochrome / Q000378:metabolism / Q000502:physiology*; D063245:Plant Development; D010944:Plants / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism
D010834:Phytochrome