Colocalization of QTL for Gibberella Ear Rot Resistance and Low Mycotoxin Contamination in Early European Maize

Gibberella ear rot (GER) of maize (Zea mays L.) caused by Fusarium graminearum Schwabe is a major disease in Europe that reduces grain yield and leads to contamination with deoxynivalenol (DON) and zearalenone (ZEA), two important mycotoxins. The objectives of our study were to (i) estimate quantitative-genetic parameters for GER severity and DON and ZEA contaminations, (ii) map quantitative trait loci (QTL) for GER resistance and low DON and ZEA contaminations, and (iii) examine the prospects of marker-assisted selection (MAS) for these traits. The materials comprised 150 doubled haploid lines from a cross of two maize inbreds that were evaluated in four environments under artificial inoculation with F. graminearum. On the basis of entry means across environments, heritabilities were moderately high (0.65–0.77), and QTL analyses identified four to six QTL for these traits. Colocalization of QTL in bins 1.11 and 2.04, which had large effects and together explained 29 to 35% of the total genotypic variance, suggested the presence of pleiotropic QTL. This was supported by strong genotypic correlations among these traits (0.89–0.95). In view of the lower costs of genotyping compared with field trials and mycotoxin determinations, our study showed that in breeding for GER resistance and low DON and ZEA contaminations, MAS should be conducted in off-season nurseries and MAS in combination with phenotypic selection in the crop season.