Abstract
To better understand the origin and evolution of photomorphogenesis mediated by phytochrome, we used a basal land plant, the liverwort Marchantia polymorpha L as a model. Phytochrome in M. polymorpha is encoded by a single-copy gene, MpPHY, and exhibits red/far-red photoreversibility in vitro. Furthermore, Mpphy is largely localized in the nucleus after red-light irradiation. Mpphy has been shown to promote cell division after spore germination and development from gemma to thallus, and to suppress the growth phase transition from vegetative to reproductive. In this study, to clarify the tissue-specific expression of MpPHY, the GUS reporter gene was expressed under the control of the MpPHY promoter in transgenic plants and GUS staining was detected in whole thallus. There are two types of phytochromes, one is light-labile (type I) and the other is light-stable (type II) in angiosperm. We raised Mpphy-specific antibody to examine light stability of Mpphy in vivo. Mpphy accumulated in the dark was stable by light irradiation. These results suggest that Mpphy, which is only one molecular species has a character of type II phytochrome in angiosperm.
