title: Circadian and Plastid Signaling Pathways Are Integrated to Ensure Correct Expression of the CBF and COR Genes during Photoperiodic Growth.
abstract: The circadian clock synchronizes a wide range of biological processes with the day/night cycle, and correct circadian regulation is essential for photosynthetic activity and plant growth. We describe here a mechanism where a plastid signal converges with the circadian clock to fine-tune the regulation of nuclear gene expression in Arabidopsis (Arabidopsis thaliana). Diurnal oscillations of tetrapyrrole levels in the chloroplasts contribute to the regulation of the nucleus-encoded transcription factors C-REPEAT BINDING FACTORS (CBFs). The plastid signal triggered by tetrapyrrole accumulation inhibits the activity of cytosolic HEAT SHOCK PROTEIN90 and, as a consequence, the maturation and stability of the clock component ZEITLUPE (ZTL). ZTL negatively regulates the transcription factor LONG HYPOCOTYL5 (HY5) and PSEUDO-RESPONSE REGULATOR5 (PRR5). Thus, low levels of ZTL result in a HY5- and PRR5-mediated repression of CBF3 and PRR5-mediated repression of CBF1 and CBF2 expression. The plastid signal thereby contributes to the rhythm of CBF expression and the downstream COLD RESPONSIVE expression during day/night cycles. These findings provide insight into how plastid signals converge with, and impact upon, the activity of well-defined clock components involved in circadian regulation.
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87 Umea, Sweden.
authors.forename: Louise
authors.initials: L
authors.lastname: Norén
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87 Umea, Sweden.
authors.forename: Peter
authors.identifier: 0000-0003-0947-2648
authors.initials: P
authors.lastname: Kindgren
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87 Umea, Sweden.
authors.forename: Paulina
authors.identifier: 0000-0002-7476-1043
authors.initials: P
authors.lastname: Stachula
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87 Umea, Sweden.
authors.forename: Mark
authors.identifier: 0000-0002-2661-5535
authors.initials: M
authors.lastname: Rühl
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87 Umea, Sweden.
authors.forename: Maria E
authors.identifier: 0000-0003-2038-4892
authors.initials: ME
authors.lastname: Eriksson
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87 Umea, Sweden.
authors.forename: Vaughan
authors.identifier: 0000-0001-5151-5184
authors.initials: V
authors.lastname: Hurry
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-901 87 Umea, Sweden asa.strand@umu.se.
authors.forename: Åsa
authors.identifier: 0000-0001-6664-0471
authors.initials: Å
authors.lastname: Strand
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects / Q000235:genetics*; D004952:Esters / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D017440:Photoperiod; D018087:Plastids / Q000187:drug effects / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D059748:Proteolysis / Q000187:drug effects; D011524:Protoporphyrins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D045725:Tetrapyrroles / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004952:Esters; D018841:HSP90 Heat-Shock Proteins; D011524:Protoporphyrins; D045725:Tetrapyrroles; C028025:protoporphyrin IX; D008274:Magnesium