Carbohydrate, phenolic and antioxidant level in relation to chlorophyll a content in oilseed winter rape (Brassica napus L.) inoculated with Leptosphaeria maculans

The relationships between the level of chlorophyll a, and the content of soluble carbohydrates, phenolics and low molecular antioxidants in the leaves of three oilseed winter rape varieties with different resistance to Leptosphaeria maculans were determined. During pathogenesis, an increase in the content of chlorophyll a in the resistant and medium-sensitive rape varieties was observed. In these varieties, the level of chlorophyll a significantly correlated with the content of primary metabolites in the form of soluble sugars, as well as with the level of free and cell wall-bound phenolics, and low-molecular antioxidants. In contrast, a decrease in soluble carbohydrates, observed during the pathogenesis in the susceptible variety, was accompanied by lower level of chlorophyll a and with high activity of reactive oxygen species. Significant correlations were also confirmed for the cell wall-bound phenolics and water content in the leaves of the resistant and medium-sensitive variety.