title: Light quality-dependent nuclear import of the plant photoreceptors phytochrome A and B
abstract: The phytochrome (phy) family of plant photoreceptors controls various aspects of photomorphogenesis. Overexpression of rice phyA-green fluorescent protein (GFP) and tobacco phyB-GFP fusion proteins in tobacco results in functional photoreceptors. phyA-GFP and phyB-GFP are localized in the cytosol of dark-adapted plants. In our experiments, red light treatment led to nuclear translocation of phyA-GFP and phyB-GFP, albeit with different kinetics. Red light-induced nuclear import of phyB-GFP, but not that of phyA-GFP, was inhibited by far-red light. Far-red light alone only induced nuclear translocation of phyA-GFP. These observations indicate that nuclear import of phyA-GFP is controlled by a very low fluence response, whereas translocation of phyB-GFP is regulated by a low fluence response of phytochrome. Thus, light-regulated nucleocytoplasmic partitioning of phyA and phyB is a major step in phytochrome signaling.
authors.affiliation: Institut fur Biologie II/Botanik, Universitat Freiburg, Schanzlestrasse 1, D-79104 Freiburg, Germany.
authors.initials: S
authors.lastname: Kircher
authors.initials: L
authors.lastname: Kozma-Bognar
authors.initials: L
authors.lastname: Kim
authors.initials: E
authors.lastname: Adam
authors.initials: K
authors.lastname: Harter
authors.initials: E
authors.lastname: Schafer
authors.initials: F
authors.lastname: Nagy