Abstract
To better understand the functions of phytochrome, we used the liverwort Marchantia polymorpha, which is haploid and has a simple body structure, as a unique model plant. We isolated a phytochrome gene in M. polymorpha, MpPHY. Southern-blot analysis suggested that MpPHY is a single-copy gene, whereas higher plants carry two or more copies of phytochrome gene. Mpphy(N612) showed Red/Far-Red photoreversibility typical of functional phytochrome in vitro. A single amino acid substitution mutant of Mpphy(N612), MpphyY241H(N612), exhibited no photoreversibility. In transgenic plants expressing MpphyY241H, formation of rhizoid was promoted regardless of light condition, and the blue light response was supressed. The MpphyY241H-GFP fusion protein localized in the nucleus forming speckles. These results indicate that MpphyY241H functions as a constitutively active form in M. polymorpha, and Mpphy controls photomorphogeneses.
