LIPID-PEROXIDATION IN TOBACCO-LEAVES TREATED WITH THE ELICITOR CRYPTOGEIN - EVALUATION BY HIGH-TEMPERATURE THERMOLUMINESCENCE EMISSION AND CHLOROPHYLL FLUORESCENCE

Treatment of excised tobacco leaves with the fungal elicitor cryptogei n progressively induced lipid peroxidation. In a first step, evidence was provided by the accumulation of thiobarbituric acid reactive subst ances (TBARS) and in a second step, the process was monitored for a 26 h period by high-temperature thermoluminescence (TL) emission, showin g a close correlationship with the TEARS data. Differences in the temp erature-associated F-0 rise (constant fluorescence) and in fluorescenc e emission spectra point to a progressive destabilization of the thyla koid membrane, especially affecting Photosystem II (PS II). In paralle l, the PS II quantum efficiency (Delta F/F-m) and the F-v/F-m ratio of chlorophyll fluorescence induction decreased significantly over the 2 4 h period.