Figure 1.

FRc preirradiation leads to a reduction in greening and nuclear gene expression following transfer to WL. A, Greening of cotyledons under different WL fluence rates after growth in the dark or FRc. Seedlings were germinated without Suc in the dark for 2 d. They were subsequently grown for a further period (as indicated) under FRc (white symbols) or were maintained in the dark (black symbols) for the equivalent period. Seedlings were then transferred to a WL source of 250 μmol m⁻² s⁻¹ (circles) or 8 μmol m⁻² s⁻¹ (triangles). B, HEMA1 and Lhcb mRNA accumulation under WL (130 μmol m⁻² s⁻¹) following a 1- or 3-d FRc pretreatment. Seedlings were grown without Suc. The RNA gel blot was sequentially hybridized with probes for HEMA1, Lhcb, and 18S transcripts. C, Effect of an FR pretreatment on the subsequent response to WL of a HEMA1 promoter:β-glucuronidase A (gusA) transgene. Transgenic WT or phyA Arabidopsis seedlings were germinated for 1 d in the dark followed by a 1- or 3-d FRc treatment (or equivalent darkness). Seedlings were then transferred to WL (8 μmol m⁻² s⁻¹) for 3 d prior to measurement of GUS activity. Data shown are the mean ± se (n = 3).