Abstract
In the moss, Physcomitrella patens, phytochrome is involved in branch formation, phototropism, and chloroplast photomovement. At least 4 PHY genes are known in P. patens. In the present study, functions of the phy species were analyzed by overexpression of PHY cDNA fused to YFP. When photoinduction of branch formation was examined, promotion of the response was observed in the overexpressors, being dependent on the phy species expressed. Intracellular localization of phy as detected by YFP fluorescence also showed differences among the phy species. In the light-grown cells, phy located in the cytoplasm and also in the nucleus as speckles. Nuclear-cytoplasmic partitioning showed a difference among the species. Interestingly, nuclear speckles were also seen in the dark-grown cells and their abundance depended on the phy species. These evidences suggest the possible functional difference of each phy species in the photoresponse.
