The Circadian Clock Modulates Global Daily Cycles of mRNA Ribosome Loading

Genome-wide translation state profiling in Arabidopsis thaliana seedlings reveals extensive translational regulation of key biological processes.

• Translation of mRNAs for ribosomal proteins and mitochondrial respiration peaks at night.
• Central clock mRNAs experience fluctuations in ribosome loading.
• No consistent phase relationship exists between peak translation states and peak transcript levels.
• Plants overexpressing the clock gene CCA1 show phase shifts in peak translation, often delaying by 6 hours.
• Under continuous light, cycles of ribosome loading in wild-type plants collapse in the CCA1 overexpressor.
• The CCA1-ox strain's transcript abundance pattern is broadly correlated with the light-dark environment.

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