Pathogen defense mechanisms against Verticillium longisporum in Brassica napus L. : investigation on the role of sulfur-containing compounds

Abstract

Reduction in atmospheric sulfur deposition and the use of low-sulfur fertilizers in an intensified agriculture have led to a widespread nutrient disturbance in the crop production. Sulfur deficiency was observed and in parallel a higher susceptibility to biotic stresses. Sulfur-enhanced defense compounds were postulated. Recently, the spread of fungal pathogens such as Verticillium longisporum, a soil borne pathogenic fungus was observed resulting in high yield losses in the plant family Brassicaceae. This pathogen preferably infects the high sulfur-demanding crop species Brassica napus L. by entering through the roots and spreading via the xylem. Defense response of plants are linked to sulfur-containing compounds including glucosinolates (GSLs), whereby abiotic and biotic stress factors can cause increased synthesis rates. A number of biological processes such as innate immunity in plants are under circadian control. Therefore, pathogens seem to carry out their attacks at specific time periods during the day.