Advanced backcross selection for resistance to Fusarium ear rot and fumonisin in maize

Ear rots and mycotoxin contamination in maize (Zea mays L.) pose a threat to maize production and food safety, best ameliorated by breeding for resistance. In this study, we introgressed alleles conferring resistance to Fusarium ear rot and fumonisin contamination from GE440, a highly resistant inbred with poor agronomic performance, into LH132, a more susceptible but agronomically elite commercial inbred, to create improved lines with resistance without compromising grain yield or other agronomic traits. On average, the selected backcross lines and their topcross hybrids had, on average, lower Fusarium ear rot and fumonisin content than their recurrent parent LH132 or its topcross hybrid, respectively. The most resistant backcross lines were superior to LH132 for resistance and produced hybrids with similar yield and agronomic performance. The backcross-derived lines were genotyped, facilitating the identification of two introgression regions conferring resistance to Fusarium ear rot and one for fumonisin content. These regions are large and contain hundreds of genes but are concordant with previous Fusarium ear rot resistance mapping studies, and the lines developed here can be used for higher-resolution genetic mapping.