In or out – photoreceptors in motion

Abstract

Higher plants possess at least three photoreceptor systems: phytochromes (PHY), which exist in two interconvertible forms absorbing in red light (R) and far-red light (FR), blue (B)/UV-A photoreceptors, and UV-B photoreceptors. In Arabidopsis, five different phytochromes (PHYA–E) and three B/UV-A receptors (CRY1, CRY2, phototropin) have been identified, although the nature of the UV-B receptor remains elusive. In addition, phytochrome-like proteins from lower organisms with typical features of photoreceptors have been characterized. A recent symposium**European Symposium on Photomorphogenesis, Free University of Berlin, Germany, 21–26 March 1999. focussed on the complex nature of the plant response to light and included key contributions on photoperception and signal transduction in prokaryotes and eukaryotes. The topics featured included a description of ancestral phytochrome-like proteins (PLPs), primary phytochrome responses in cyanobacteria and new aspects of phytochrome and Blue/UV-A receptor action in Arabidopsis.