Production of O₂^- in thylakoid membranes isolated from control and ALA-treated WT Arabidopsis plants.

Thylakoid membranes were isolated from leaves before the day-break in dark and were suspended at a concentration of 1 mg Chl ml⁻¹. The thylakoid membranes were illuminated by incandescent light (500 µmoles photons m⁻² s⁻¹) passed through heat and neutral density filters. O₂^- generation by the thylakoid membranes was monitored as cytochrome C reduction.