Daily cycles of chemical changes controlling gene activity in the central clock of Arabidopsis

Histone H3 acetylation and tri-methylation levels at clock genes in Arabidopsis are positively correlated with their rhythmic transcript levels.

• LHY and CCA1 transcripts are highly expressed in the morning, while TOC1 expression peaks in the evening.
• The proteins LHY and CCA1 repress TOC1, creating a negative feedback loop that regulates the circadian clock.
• Histone modifications such as H3 acetylation and H3K4 trimethylation are associated with the rhythmic expression of LHY, CCA1, and TOC1.
• In contrast, H3K36 dimethylation shows a negative correlation with the transcript levels of these clock genes.
• These findings suggest that rhythmic transcription of Arabidopsis clock genes may be influenced by changes in histone modifications.

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