Fusarium Head Blight (FHB) is a destructive disease that affects the grain yield and quality of cereals. The relationship between the natural defense chemicals benzoxazinoids and the FHB resistance of field grown winter wheat varieties was investigated. FHB resistance was assessed by the inoculation of wheat ears with mixtures of Fusarium avenaceum, Fusarium culmorum, Fusarium graminearum, and Microdochium nivale. The benzoxazinoids detected in the highest concentration were 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one (3.7-9.4 mu mol/kg DW) and 2-hydroxy-7-nnethoxy-(2H)-1,4-benzoxazin-3(4H)-one (HMBOA, 2.0-11 mu mol/kg DW). The cultivars most susceptible to FHB were cvs. Hanseat, Asketis, and Ritmo, while cvs. Petrus, Terra, and Hattrick showed high resistance. 2-O-beta-D-Glucopyranosyloxy-4,7-dimethoxy-(2H)-1,4-benzoxazin-3(4H)-one (HMBOA-glc) and 2-O-beta-D-glucopyranosyloxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one (HMBOA-glc) were detected. HMBOA-glc was found in higher concentrations than 2-O-beta-D-glucopyranosyloxy-2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one (DIMBOA-glc). Principal component analyses demonstrated correlation between the susceptibility to FHB and the concentrations of DIMBOA-glc, HMBOA-glc, HMBOA, 2-O-beta-D-glucopyranosyloxy-4-hydroxy-(2H)-1,4-benzoxazin-3(4H)-one (DIBOA-glc), 2-O-beta-D-glucopyranosyloxy-1,4-benzoxazin-3(4H)-one, and 2-O-beta-D-glucopyranosyloxy-4-dihydroxy-(2H)-7,8-dimethoxy-1,4-benzoxazin-3(4H)-one (DIM(2)BOA-glc). (C) 2007 Elsevier Ltd. All rights reserved.