Direct regulation of abiotic responses by the Arabidopsis circadian clock component PRR7.

Up to 30% of the plant transcriptome is circadian clock-regulated in different species; however, we still lack a good understanding of the mechanisms involved in these genome-wide oscillations in gene expression. Here, we show that PSEUDO-RESPONSE REGULATOR 7 (PRR7), a central component of the Arabidopsis clock, is directly involved in the repression of master regulators of plant growth, light signaling and stress responses. The expression levels of most PRR7 target genes peak around dawn, in an antiphasic manner to PRR7 protein levels, and were repressed by PRR7. These findings indicate that PRR7 is important for cyclic gene expression by repressing the transcription of morning-expressed genes. In particular we found an enrichment of the genes involved in abiotic stress responses, and in accordance we observed that PRR7 is involved in the oxidative stress response and the regulation of stomata conductance.