Figure 1.

FHY3 and FAR1 Are Required for Light-Induced CCA1 Expression.

(A) qRT-PCR analysis showing the light-induced regulation of CCA1 expression in various light signaling-related mutants. Five-day-old dark-grown Arabidopsis seedlings were treated with a 1-min pulse of white light (WL) and incubated in the dark for 2 h before harvesting (*, P < 0.05, Student’s t test; n.s. no significance). Values are means ± sd (n = 3 technical replicates). Two independent biological replicates (see Methods) showed similar results.

(B) qRT-PCR analysis showing the effects of light treatment at different ZTs on the expression of CCA1. Wild-type and fhy3 far1 seedlings were grown in 12L:12D conditions for 5 d before being transferred to continuous darkness. Beginning at ZT44, seedlings were exposed to light for 1 h at different time points (ZT44 to ZT72) and immediately harvested for RNA extraction. Seedlings grown in the dark at the corresponding time points were used as controls. The CCA1 expression level was normalized to PP2A (*, P < 0.05 and **, P < 0.01, Student’s t test; left panel). The ratio of CCA1 expression in seedlings subjected to 1 h of light treatment versus dark-grown seedlings was used to evaluate the effects of light treatment at different time points (right panel). Different letters indicate significant differences by one-way ANOVA with SAS software (P < 0.05). Two independent biological replicates showed similar results.