Circadian rhythms are endogenous biological rhythms that oscillate with an approximately 24-hour period. These rhythms are generated by a network of transcriptional and post-transcriptional feedback loops known as the circadian clock. Circadian rhythms help plants and other organisms thrive in their environment, wherein the clock fine-tunes physiological responses to anticipate daily environmental oscillations.

Previous studies have identified REVEILLE8 ( RVE8) and its close homologs REVEILLE4 ( RVE4) and REVEILLE6 (RVE6) as partially redundant Myb-like transcription factors in the Arabidopsis circadian oscillator. We further defined the roles in the clock of the remaining RVE8 subclade members REVEILLE3 (RVE3) and REVEILLE5 (RVE5). This study illustrates that the RVE8 subclade members function partially redundantly to control light input to the core oscillator, and that they repress plant growth at both early and late stages of development via a PHYTOCHROME INTERACTING FACTOR PIF4 and PIF5 mediated pathway.

In addition to investigating the role of the RVE8 subclade in transcriptional regulation, we studied post-transcriptional mechanisms regulating rhythmic oscillations of RVE8 protein. We show here that RVE8 protein is degraded in a circadian specific manner and is stabilized by blue light. Additionally, we generated molecular tools to investigate the protein accumulation patterns and post-transcriptional control of the remaining RVE8 subclade proteins to better understand the mechanisms beyond transcription that control the circadian clock in Arabidopsis.