title: Phytochrome Signaling Is Mediated by PHYTOCHROME INTERACTING FACTOR in the Liverwort Marchantia polymorpha.
abstract: Phytochromes are red light (R) and far-red light (FR) receptors that play important roles in many aspects of plant growth and development. Phytochromes mainly function in the nucleus and regulate sets of genes by inhibiting negatively acting basic helix-loop-helix transcription factors named PHYTOCHROME INTERACTING FACTORs (PIFs) in Arabidopsis thaliana Although R/FR photoreversible responses and phytochrome genes are well documented in diverse lineages of plants, the extent to which phytochrome signaling is mediated by gene regulation beyond angiosperms remains largely unclear. Here, we show that the liverwort Marchantia polymorpha, an emerging model basal land plant, has only one phytochrome gene, Mp-PHY, and only one PIF gene, Mp-PIF These genes mediate typical low fluence responses, which are reversibly elicited by R and FR, and regulate gene expression. Mp-phy is light-stable and translocates into the nucleus upon irradiation with either R or FR, demonstrating that the single phytochrome Mp-phy exhibits combined biochemical and cell-biological characteristics of type I and type II phytochromes. Mp-phy photoreversibly regulates gemma germination and downstream gene expression by interacting with Mp-PIF and targeting it for degradation in an R-dependent manner. Our findings suggest that the molecular mechanisms for light-dependent transcriptional regulation mediated by PIF transcription factors were established early in land plant evolution.
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Nishihama
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Kataoka
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Hosaka
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Manabe
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Nomoto
authors.affiliation: Center for Gene Research, Nagoya University, Chikusa, Nagoya 464-8602, Japan.
authors.forename: Yasuomi
authors.initials: Y
authors.lastname: Tada
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan Graduate School of Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Kimitsune
authors.identifier: 0000-0003-0504-8196
authors.initials: K
authors.lastname: Ishizaki
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan tkohchi@lif.kyoto-u.ac.jp.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kohchi
mesh_terms: D017360:Arabidopsis / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000528:radiation effects; D008027:Light; D047008:Marchantia / Q000378:metabolism* / Q000528:radiation effects; D010834:Phytochrome / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D010834:Phytochrome; D010940:Plant Proteins; D014157:Transcription Factors