Abstract
Phytochrome signaling involves a complex network of processes with branches taking place in distinct cellular and subcellular compartments. For long time, phytochtomes were considered cytoplasmic proteins. However, it is now known that photoconversion of phyA and phyB to their active forms triggers nuclear translocation. For phyB, nuclear translocation is necessary and sufficient to control seedling deetiolation. However, for phyA, the subcellular sites for the control of deetiolation responses remained to be investigated. We have produced two new types of GFP-fusion transgenic plants expressing phyA-GFP with a nuclear localization signal (APAGL) or with a nuclear export signal (APAGE) under the PHYA promoter and in the phyA mutant background. The predicted subcellular distribution and protein accumulation levels comparable to the Wt-phyA were corroborated. Selected lines are being used to dissect effects of altered subcellular compartmentalization on phyA signaling. Results on the physiological and cell-biological characterization of these lines will be discussed.
