How Gene Activation and Repression Shape the Plant Biological Clock and Its Feedback and Output Systems

Transcription factors in plant circadian clocks may function as both activators and repressors of gene expression.

• The plant circadian clock consists of interconnected feedback loops involving transcriptional activators and repressors.
• Most identified transcription factors in these loops are repressors, suggesting a model dominated by repressive interactions.
• Recent studies indicate the presence of transcriptional activators in newly identified feedback loops.
• Some transcription factors may act as both activators and repressors, expanding understanding of clock regulatory mechanisms.
• The review provides a framework for understanding the roles of transcriptional activation and repression in core oscillator genes.

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