No time for spruce: rapid dampening of circadian rhythms in Picea abies (L. Karst)

• Published in: Plant and cell physiology 2014-03, Vol.55 (3), p.535-550
• Main Authors: Gyllenstrand, Niclas, Karlgren, Anna, Clapham, David, Holm, Karl, Hall, Anthony, Gould, Peter D, Källman, Thomas, Lagercrantz, Ulf
• Format: Article
• Language: English
• Subjects: circadian clock; Circadian Clocks - genetics; Circadian Clocks - physiology; Circadian Rhythm - genetics; Circadian Rhythm - physiology; delayed fluorescence; Developmental Biology; diurnal cycling; gene expression; Gene Expression Regulation, Plant; Genetics; Genetik; Phylogeny; Picea - classification; Picea - genetics; Picea - physiology; Picea abies; Plant Biotechnology; Real-Time Polymerase Chain Reaction; Utvecklingsbiologi; Växtbioteknologi
• ISSN: 0032-0781; 1471-9053; 1471-9053
• DOI: 10.1093/pcp/pct199

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.