Figure 7.

Effects of UV radiation on the relative variable fluorescence of tobacco transgenics altered in the expression of the anionic peroxidase. Plants were raised under long-day conditions in the greenhouse. Leaf discs were exposed for 24 h to 4.4-W m⁻² UV. Before (□) and after (▪) UV treatment, the minimal fluorescence (F_o) and the maximal fluorescence (F_m) were measured on dark-adapted samples. Values represent averages of 15 to 21 measurements. ses of the mean are given. Statistical analysis (Student's t test) shows that the antisense line differs from both WT (P < 0.01) and overexpressor (P < 0.01), and that the WT differs from the overexpressor (P < 0.10), following UV treatment.