HY5, HYH, and UNE10 are late induced by low R/FR largely through the action of phyA. A, RT-qPCR analyses of PHYA in Col-0 and HY5 in Col-0 and phyA-211 upon exposure to low R/FR for different times. Col-0 and phyA-211 seedlings were grown for 7 d in a L/D cycle (16/8 h) in high R/FR (control) and then maintained in high R/FR or transferred to low R/FR for different times. The graphs show the relative expression levels in high (dashed lines) and low (solid lines) R/FR of PHYA in Col-0 and HY5 in Col-0 and phyA-211. Each value is the mean ± sd of three biological replicates normalized to EF1α expression. Statistical significance was assessed by means of one-way ANOVA followed by Dunnett’s test. ◊P < 0.001 for low R/FR versus control (0) in Col-0. Statistical significance between different backgrounds was assessed by means of two-way ANOVA followed by the Bonferroni posthoc test. B, RT-qPCR analyses of HYH and UNE10 in Col-0 and phyA-211 upon exposure to low R/FR for different times. Col-0 and phyA-211 seedlings were grown and treated as described in A. The graphs show the relative expression levels in high (dashed lines) and low (solid lines) R/FR of HYH and UNE10 in Col-0 and phyA-211. Each value is the mean ± sd of three biological replicates normalized to EF1α expression. Statistical significance between different treatments and backgrounds was assessed by means of two-way ANOVA followed by the Bonferroni posthoc test. C, RT-qPCR analyses of HY5, HYH, and UNE10 upon prolonged exposure to low R/FR in Col-0, hfr1-4/sics1-1, and phyA-211.
Col-0, hfr1-4/sics1-1, and phyA-211 seedlings were grown for 7 d in a L/D cycle (16/8 h) in high R/FR and then either maintained in high R/FR or transferred to low R/FR under the same L/D regimen for 1 d. Plant transfer to low R/FR was performed 4 h after the beginning of the light period. The graphs show the relative expression levels in high and low R/FR of HY5, HYH, and UNE10 in the different genotypes. PHYB is a gene not differentially regulated by low R/FR in mutant seedlings relative to the wild type. Each value is the mean ± sd of five biological replicates normalized to EF1α expression. Statistical significance was assessed by means of one-way ANOVA followed by Tukey’s test. *P < 0.001 for Col-0 low R/FR versus Col-0 high R/FR; §P < 0.001 for hfr1-4/sics1-1 low R/FR versus hfr1-4/sics1-1 high R/FR; ^P < 0.001 for phyA-211 low R/FR versus phyA-211 high R/FR.