Correlations among Fusarium culmorum head blight resistance, fungal colonization and mycotoxin contents in winter rye

Abstract

Abstract Fusarium culmorum head blight infections may lead to accumulation of toxic metabolites in winter rye grain. To estimate the correlation between resistance traits, fungal colonization and accumulation of deoxynivalenol (DON), 3‐acetyldeoxynivalenol (3‐AcDON) and zea‐ralenone (ZEA), 27 winter rye single‐cross hybrids were artificially inoculated in 1992 and 1993. Resistance traits were head blight rating and grain weight of the inoculated relative to the non‐inoculated plots. Fungal colonization was determined by the analysis of ergosterol (ERG) content in the grain. Head blight rating and relative grain yield showed a medium to high disease severity and ERG indicated a considerable fungal colonization of the kernels with a mean of 85 mg/kg in 1992 and 66 mg/kg in 1993. DON content among genotypes ranged from 0.7–28 mg/kg in 1992 and from 11 to 35 mg/kg in 1993. 3‐AcDON and ZEA contents were low in both years with overall means of 1.1 and 0.09 mg/kg, respectively. Across both years, considerable genotypic variation was found for head blight rating, relative grain weight, and ERG content with medium to high heritabilities (0.6–0.7). For the mycotoxin contents, however, genotype‐year interaction variance was the most important source of variation. The correlations between relative grain weight and DON, 3‐AcDON, or ZEA were low in 1992 (r ∼ 0.3), but considerably higher in 1993 (r ∼ 0.7, P = 0.01). In contrast, correlation between relative grain weight and ERG was significant in both years (r ∼ 0.5, P = 0.01). In F. culmorum head blight infections, DON, 3‐AcDON and ZEA contents appear to be affected, at least partially, by different environmental factors than resistance traits and fungal colonization.