QTL mapping of resistance to Gibberella ear rot in maize

Abstract

Gibberella ear rot (GER), caused by the fungal pathogen Fusarium graminearum, is becoming one of the most prominent pathogens responsible for ear rot in maize. In this study three F2 populations, F2-C, F2-D, and F2-J, and their corresponding F2:3 families, were constructed by crossing three highly GER-resistant inbred lines—Cheng351, Dan598, and JiV203—with the susceptible line ZW18. We used this cross for genetic analysis and QTL mapping of resistance to GER. Analysis of variance of GER in the three F2 populations revealed the presence of significant differences among genotypes and between locations. The broad-sense heritability (H2) of GER resistance was estimated to be 0.68, 0.63, and 0.64 in the three F2 populations, indicating that genetic factors play a key role in the development of phenotypic variation. Seventeen QTLs conferring resistance to GER were detected in the three F2 populations, among which the QTL qRger7.1, originating from the resistant parent Cheng351, explained 20.16–41.84% of the phenotypic variation. The physical support interval of qRger7.1 exhibited approximately 2 Mb overlap with that of qRger7.2, which was derived from the resistant parent Dan598, supporting the identification of potential “hotspots” of the target QTLs. QTLs derived from the resistant parents Dan598 and JiV203 accounted for 59.67–61.28% and 65.82–66.90%, respectively, of the phenotypic variation. The GER-resistant QTLs identified in this study are useful candidates for improving the resistance to GER in maize using molecular marker-assisted selection.