Figure 4.

ABA can utilize the same signaling pathway as BL to elicit Lhcb expression in etiolated seedlings. A, Response to 10² μmol m⁻² BL and 800 nm ABA. Six-day-old dark-grown seedlings from matched seed lots of wild-type Col Arabidopsis and T-DNA insertions in GCR1 (SALK_027808), GPA1 (SALK_066823), PRN1 (SALK_006939), NF-Y-B9 (LEC1; SALK_000450), NF-Y-A5 (SALK_006559), and NF-Y-B6 (LEC1 LIKE; SALK_118236) were sprayed with ABA (800 nm) in ethanol, or ethanol alone (DK), or irradiated with a single pulse of low-fluence BL (10² μmol m⁻²) immediately followed by spraying with 800 nm ABA. Treated seedlings were placed back in the dark for 2 h after which total RNA was extracted and used for northern-blot analysis as described in Figure 1. Data shown represent induction levels (ABA/DK or BL-ABA/DK). Data derive from at least three independent replicates. Bars represent the se of the mean. B, Response to 10⁴ μmol m⁻² BL and 800 nm ABA. Seedlings were grown and treated the same as described for Figure 4A, except that a near saturating dose of BL (10⁴ μmol m⁻²) was used in the treatment. RNA extraction and analysis was also the same as for samples in Figure 4A.