%0 Journal Article
%T Expression conservation within the circadian clock of a monocot: natural variation at barley Ppd-H1 affects circadian expression of flowering time genes, but not clock orthologs
%A Chiara Campoli
%A Munqez Shtaya
%A Seth J Davis
%A Maria von Korff
%J BMC Plant Biology
%D 2012
%I BioMed Central
%R 10.1186/1471-2229-12-97
%X Barley clock orthologs HvCCA1, HvGI, HvPRR1, HvPRR37 (Ppd-H1), HvPRR73, HvPRR59 and HvPRR95 showed a high level of sequence similarity and conservation of diurnal and circadian expression patterns, when compared to Arabidopsis. The natural mutation at Ppd-H1 did not affect diurnal or circadian cycling of barley clock genes. However, the Ppd-H1 mutant was found to be arrhythmic under free-running conditions for the photoperiod-response genes HvCO1, HvCO2, and the MADS-box transcription factor and vernalization responsive gene Vrn-H1.We suggest that the described eudicot clock is largely conserved in the monocot barley. However, genetic differentiation within gene families and differences in the function of Ppd-H1 suggest evolutionary modification in the angiosperm clock. Our data indicates that natural variation at Ppd-H1 does not affect the expression level of clock genes, but controls photoperiodic output genes. Circadian control of Vrn-H1 in barley suggests that this vernalization responsive gene is also controlled by the photoperiod-response pathway. Structural and functional characterization of the barley circadian clock will set the basis for future studies of the adaptive significance of the circadian clock in Triticeae species.The circadian clock is an autonomous oscillator that produces endogenous biological rhythms with a period of about 24 hours. This clock allows organisms to anticipate predicted daily changes in the environment and to coordinate developmental and metabolic processes with environmental cues, such as light and temperature, that cycle with the rotation of the earth [1-5]. Conceptually, a circadian system comprises three basic components: input pathways that sense light and temperature, a core oscillator that defines the rhythm, and output pathways that control various developmental and metabolic processes, resulting in the optimal adaptation to daily changing environments. The core oscillator that generates circadian rhythms is comprised of
%K Hordeum vulgare
%K Circadian Clock
%K Photoperiod
%K Flowering
%K Ppd-H1
%U http://www.biomedcentral.com/1471-2229/12/97