ChIP-Seq profiling of ELF3,PRR37 and PHYC in response to photoperiod change at different ZTime in Brachypodium distachyon

Daylength is an important seasonal cue, and genetic variation in the regulation of photoperiodism has been selected for in adapting wheat and barley to northern latitudes. Despite the importance of this trait, the mechanism by which monocot plants sense photoperiod is not known. We find in Brachypodium distachyon that photoperiodism is mediated by phytochromeC (phyC), a chromophore that acts as a molecular timer and measures the length of the night. The phyC signal is directly communicated to the circadian clock via the activity of EARLY FLOWERING3 (ELF3). ELF3 is a central regulator of photoperiodism, and elf3 mutants display a constitutive long day transcriptome. By coordinating an endogenous timer for night length perception with rhythmical circadian clock controlled gene expression, this mechanism resolves how Brachypodium, and likely other monocots, perceive photoperiod. Using ChIP-Seq, we detected that occupancy of ELF3 at various genomic regions varies in response to photoperiod and ZTime. Single samples were taken at each time point. ELF3,PHYC,PRR37 ChIP-Seqs were sampled at different photoperiod and ZTime.