Abstract
Arabidopsis Pseudo Response Regulator (PRR) genes are components of the circadian clock mechanism. In order to understand the scope of genome-wide transcriptional regulation by PRR genes, a microarray analysis was performed for a prr9-11 prr7-10 prr5-10 triple mutant (d975) using mRNA collected during late daytime. Night genes expression were increased and day genes expression were decreased toward the dusk, but expression of these genes was constant in d975. Night genes expression levels were lower, whereas day genes were higher in d975 than wild-type. Bioinformatics approaches indicated that up-regulated genes in d975 and cold-responsive genes have significant overlap. We found that d975 are more tolerant to cold stresses than wild-type. These results suggest that PRR9, PRR7, and PRR5 are involved in the mechanism that anticipates diurnal cold stress coming, and prepares stress response, by mediating cyclic expression of stress response genes.
