Identification of a major quantitative trait locus, qGER4.2, conferring resistance to Gibberella ear rot in maize using a Chinese recombination inbred line population

Abstract

Background: Gibberella ear rot (GER), a prevalent disease caused by Fusarium graminearum, can result in yield loss and mycotoxin contamination in maize. Despite that several QTLs related to GER resistance have been reported previously, few of them was identified in Chinese maize inbred lines. In this study, we employed a Chinese recombination inbred line (RIL) population comprising of 204 lines, developed from a cross involving a resistant parent DH4866 and a susceptible line T877. The population was phenotypically evaluated at three field trial locations under artificial inoculation with F. graminearum and genotyped with an Affymetrix microarray CGMB56K SNP Array to detect the quantitative trait loci (QTLs) for resistance to GER. Results: Based on the genetic linkage map constructed using 1,868 bins as markers, a total of 15 QTLs were identified, and both DH4866 and T877 alleles at these QTLs contributed toward resistance. Of these QTLs, five were stably expressed across multiple locations, including three co-localized with previously reported genomic regions. The largest-effect QTL located on chromosome 4, qGER4.2, which accounted for 5.66~17.10% of the phenotypic variation, was detected at all locations. Based on the phenotypic values of the alleles corresponding to the five stable QTLs, a significant correlation (r2 = 0.45) between resistance to GER and the number of resistant alleles was observed. Conclusions: QTL mapping was successfully employed to identify genetic loci conferring resistance to GER by a high-density genetic map constructed from two Chinese maize germplasms. The five stable QTLs identified, especially the large-effect QTL, qGER4.2, will be useful in maize breeding programs aimed at improving GER resistance.