EN
The fungus Leptosphaeria maculans that causes blackleg can attack winter rape throughout the entire growing season. Therefore, appropriate treatments were designed to simulate environmental factors that may occur under field conditions. The callus tissue of winter rape was treated with abiotic stress in the form of cold (2 C) and temperature change (2/20 C and 20/2 C), and biotic stress in the form of secondary metabolites of L. maculans. The following parameters were analyzed: total phenolics, the activity of L-phenylalanine ammonia lyase (PAL), catalase, respiration intensity, heat emission, and metabolic activity determined by means of 2,3,5-triphenyl-tetrazolium chloride (TTC) assay. Additionally, the changes in the electrical potential, known as a sensitive indicator of biochemical changes in the callus tissue, were measured. The obtained results seem to indicate rather increased stress, caused by temperature (2 or 20 C) or its changes (2/20 C, 20/2 C) and the secondary metabolites of L. maculans than a cross reaction. The factor that most strongly affected the metabolism of winter rape callus tissue was the temperature change, which masked the changes caused by the fungal secondary metabolites or intensified their adverse effects. The only parameters that could be regarded as reliable indicators of the callus tissue response to the elicitation with secondary metabolites of L. maculans were catalase activity and respiration intensity. Additionally, a protective function of low temperature involved a reduction in catalase activity, resulting in increased level of reactive oxygen species (ROS), key molecules inducing the defense mechanisms during pathogenesis. Only the changes in L-phenylalanine ammonia lyase (PAL) activity and the accompanying changes in the content of phenolic compounds can be considered as beneficial effects of low temperature (2 C) on a more efficient callus acclimation to the biotic stress.