Influence of the sulphur and nitrogen supply on S metabolites involved in Sulphur Induced Resistance (SIR) of Brassica napus L.

Abstract

Since the 1980s severe sulphur deficiency has been recorded in agricultural crops. An insufficient sulphur supply reduces not only crop yield and diminishes crop quality, but it also results in a higher susceptibility to certain diseases. In sulphur response trials with oilseed rape, potatoes and grapes, resistance to fungal pathogens could be induced by soil-applied sulphur. The identification of metabolites and pathways involved in sulphur-induced resistance (SIR) is crucial in order to prompt resistance mechanisms under field conditions. The main objective of the present research work was to investigate the effect of S and N nutrition on S-containing metabolites in relation to fungal infections. Two oilseed rape cultivars with different susceptibilities towards fungal pathogens were grown. The fungicide treatment was another factor of variation. The investigations were conducted on three sites which differed in climate, soil type and atmospheric S depositions: Braunschweig (Germany), Aberdeen and Inverness (Scotland). Apart from increasing the knowledge on the significance of S metabolites for plant resistance, the relevance of this work is given by the implementation of infection-directed sampling strategies and geostatistical analysis in order to achieve an advanced understanding of the interactions between pests and diseases and individual S fractions under field conditions.