title: RED AND FAR-RED INSENSITIVE 2, a RING-domain zinc finger protein, mediates phytochrome-controlled seedling deetiolation responses.
abstract: Light is arguably the most important resource for plants, and an array of photosensory pigments enables plants to develop optimally in a broad range of ambient-light conditions. The red- and far-red-light-absorbing photosensory pigments or phytochromes (phy) regulate seedling deetiolation responses, photoperiodic flowering, and circadian rhythm. We have identified a long hypocotyl mutant under red and far-red light, rfi2-1 (red and far-red insensitive 2 to 1). rfi2-1 was also impaired in phytochrome-mediated end-of-day far-red light response, cotyledon expansion, far-red light block of greening, and light-induced expression of CHLOROPHYLL A/B BINDING PROTEIN 3 and CHALCONE SYNTHASE. Introduction of rfi2-1 mutation into phyB-9 or phyA-211 did not enhance or suppress the long hypocotyl phenotype of phyB-9 or phyA-211 under red or far-red light, respectively, and RFI2 likely functions downstream of phyB or phyA. RFI2 was identified through the segregation of two T-DNA insertions into different recombinant lines, genetic rescue, and phenotypic characterization of a second mutant allele rfi2-2. RFI2 encodes a protein with a C3H2C3-type zinc finger or RING domain known to mediate protein-protein or protein-DNA interactions, and RFI2 is localized to the nucleus. RFI2 therefore reveals a signaling step that mediates phytochrome control of seedling deetiolation.
authors.affiliation: Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108, USA.
authors.forename: Mingjie
authors.initials: M
authors.lastname: Chen
authors.forename: Min
authors.initials: M
authors.lastname: Ni
mesh_terms: D000217:Acyltransferases / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D008027:Light; D008969:Molecular Sequence Data; D051942:Phytochrome A / Q000235:genetics / Q000502:physiology; D051939:Phytochrome B / Q000235:genetics / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000032:analysis; D036226:Seedlings / Q000235:genetics / Q000254:growth & development; D016415:Sequence Alignment; D015398:Signal Transduction; D016335:Zinc Fingers
chemical_list: D029681:Arabidopsis Proteins; C510310:CAB3 protein, Arabidopsis; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D051942:Phytochrome A; C510353:RFI2 protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D051939:Phytochrome B; D000217:Acyltransferases; C491135:AT5G13930 protein, Arabidopsis