Fig. 4.

Response of the wild-type Col and caa39 mutant to high-light stress conditions. Relative transcript levels of the ¹O₂-responsive AAA-ATPase, At1g24145, BAP1, ERF5, the H₂O₂-responsive FER1, PK, and APX1 genes, and the general ROS-responsive marker gene ZAT12 were analyzed in wild-type Col (closed symbols) and caa39 (open symbols) seedlings at the onset and 15 min, 30 min, 1 h, 2 h, and 4 h after the initiation of the high light (HL, 2,000 ± 50 μmol⋅m⁻² s⁻¹) treatment. Before HL stress, seedlings were grown for 5 d in normal light (NL, 80 ± 5 μmol⋅m⁻²⋅s⁻¹) 16-h light/8-h dark photoperiod conditions. Relative transcript levels were determined by quantitative RT-PCR and expressed relative to the levels in NL. Results represent mean quantification cycle values of four biological replicates ± SE.