Genomewide identification of LHY binding targets.

The plant circadian enables plants to adjust their physiology and modulate their developmental responses in anticipation of diurnal and seasonal changes in environmental conditions. Thus, it makes an important contribution to overall fitness. The complex regulatory network underlying the oscillatory mechanism of the clock is now well characterised, but we still know relatively little about how downstream processes are controlled. In order to investigate this question we identified genes that are under direct control of one of the oscillator components, a MYB transcription factor known as LATE ELONGATED HYPOCOTYL (LHY). Overall design: 2-week-old wild-type (Ws) and LHY knock-out (lhy-21) seedlings were harvested 2 h after dawn. Tissue was cross-linked using 1% formaldehyde for 10 min. Chromatin was extracted and used for immunoprecipitation using an antibody to the full-length LHY protein. The immunoprecipitated DNA was sequenced using Illumina technology. LHY binding regions were identified as genomic regions that showed over-representation of reads in the wild-type sample as compared to the LHY knock-out sample.