title: No time for spruce: rapid dampening of circadian rhythms in Picea abies (L. Karst).
abstract: The identification and cloning of full-length homologs of circadian clock genes from Picea abies represent a first step to study the function and evolution of the circadian clock in gymnosperms. Phylogenetic analyses suggest that the sequences of key circadian clock genes are conserved between angiosperms and gymnosperms. though fewer homologous copies were found for most gene families in P. abies. We detected diurnal cycling of circadian clock genes in P. abies using quantitative real-time PCR; however, cycling appeared to be rapidly dampened under free-running conditions. Given the unexpected absence of transcriptional cycling during constant conditions, we employed a complementary method to assay circadian rhythmic outputs and measured delayed fluorescence in seedlings of Norway spruce. Neither of the two approaches to study circadian rhythms in Norway spruce could detect robust ∼24 h cycling behavior under constant conditions. These data suggest gene conservation but fundamental differences in clock function between gymnosperms and other plant taxa.
authors.affiliation: Department of Plant Biology and Forest Genetics, Uppsala Biocenter, Swedish University for Agricultural Sciences, Uppsala, PO Box 7080, SE-750 07 Uppsala, Sweden.
authors.forename: Niclas
authors.initials: N
authors.lastname: Gyllenstrand
authors.forename: Anna
authors.initials: A
authors.lastname: Karlgren
authors.forename: David
authors.initials: D
authors.lastname: Clapham
authors.forename: Karl
authors.initials: K
authors.lastname: Holm
authors.forename: Anthony
authors.initials: A
authors.lastname: Hall
authors.forename: Peter D
authors.initials: PD
authors.lastname: Gould
authors.forename: Thomas
authors.initials: T
authors.lastname: Källman
authors.forename: Ulf
authors.initials: U
authors.lastname: Lagercrantz
mesh_terms: D057906:Circadian Clocks / Q000235:genetics / Q000502:physiology; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D010802:Phylogeny; D028222:Picea / Q000145:classification / Q000235:genetics* / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction
keywords: Circadian clock; Delayed fluorescence; Diurnal cycling; Gene expression; Phylogeny; Picea abies