Mycotoxin accumulation and corresponding ear rot rating in three maturity groups of European maize inoculated by two Fusarium species

Abstract

Fusarium graminearum (FG) and F. verticillioides (FV) produce the mycotoxins deoxynivalenol (DON), zearalenone (ZEA) and fumonisins (FUM), respectively, in maize. The EU released limits for these toxins in food. Growing resistant varieties is one alternative to fulfill these limits. Quantification of mycotoxin concentrations is expensive and time consuming. If indirect selection based on cost efficient and fast ear rot rating is feasible, this could increase efficiency of selection. The objective of this study was to analyze correlations between mycotoxin concentrations and ear rot rating by inoculating three maturity groups (early, mid-late, late) each comprising about 50 inbred lines tested in Central and Southern Europe. In the early maturity group flint lines were more susceptible in all instances except ZEA than dent lines. Broad ranges and significant (P < 0.01) genotypic variances were detected, but also genotype × environment interaction variances were significant (P < 0.01). Heritabilities of ear rot rating were similar or higher than those of mycotoxin concentrations (0.61−0.93 and 0.56–0.89, respectively). Although high genotypic correlations between FUM and DON or ZEA were found (0.77; 0.76, respectively), separate testing of FV and FG and corresponding mycotoxins is necessary since genotypes resistant to FV were not necessarily resistant to FG and vice versa. Medium to high heritabilities and high genotypic correlations between ear rot and corresponding mycotoxin concentrations (0.87–0.99) suggest frequent identification of lines with reduced mycotoxin concentrations by ear rot rating. Assuming fixed budgets we conclude that indirect selection by applying cost efficient ear rot rating could increase selection intensity and therefore is more effective than direct selection for reduced mycotoxin concentrations.