Figure 4.

Oxidative stress in Arabidopsis leaf discs (WT and pdx1) exposed to the ¹O₂ generator eosin (0.5%). A) Autoluminescence imaging of leaf discs exposed for 3.5 h or 5 h to eosin in the light (400 μmol photons m^-2 s^-1). 'Dark' corresponds to eosin-infiltrated leaf discs kept in the dark for 5 h. B) Autoluminescence intensity in leaf discs exposed for 0 or 5 h to eosin in the light. Data are mean values of 10 measurements + SD. *, significantly different from the WT value with P < 0.001 (t test). C) Thermoluminescence band at high temperature (ca. 135°C) in leaf discs exposed for 5 h to eosin in the light. Control, leaf discs from pdx1 kept in eosin in the dark. Control WT disks (not shown) was in the same thermoluminescence intensity range. The band peaking at ca. 60°C in the control is typical of Arabidopsis. Its origin is unknown; it is not related to lipid peroxidation and could be due to thermolysis of a (yet unidentified) volatile compound [84].