Photo-oxidation of Arabidopsis wild-type and mutant genotypes under photoxidative stress. Detached leaves on wet paper were treated at 900 μmol photons m-2 s-1 at 5°C for 3.5 h, then chlorophyll bleaching (A) and MDA formation (B) were recorded. Data are expressed as means ± SD (n = 4). Significant difference (P < 0.05 (*) or P < 0.02 (**)) against wild type within each treatment are marked. Chlorophyll and MDA contents were quantified before (t0) or after (tf) the high-light stress.