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

Authors: BUTOTO, E - North Carolina State University; Holland, James

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2025
Publication Date: 8/29/2025
Citation: Butoto, E., Holland, J.B. 2025. Advanced backcross selection for resistance to Fusarium ear rot and fumonisin contamination in maize. Crop Science. 65. https://doi.org/10.1002/csc2.70147.
DOI: https://doi.org/10.1002/csc2.70147

Interpretive Summary: Fusarium verticillioides is a common fungus that affects maize, causing Fusarium ear rot (FER) and producing fumonisin (FUM), a toxic substance harmful to humans and animals. Breeding for natural resistance to this fungus is an efficient approach to reducing its impact on corn yields and animal and human health. Previously we identified an inbred line developed by USDA in Georgia decades ago that has excellent resistance to Fusarium ear rot and fumonisin contamination. Unfortunately, this line produces hyrids with low yield potential and significant problems with lodging (falling over before harvest). We crossed this resistant line to a more susceptible but high-yielding inbred developed by a commercial seed company that is now publicly available. We backcrossed multiple times to the high yielding line, then selected the most resistant lines from the resulting population. We showed here that the best of those lines had significantly improved resistance to FER and FUM compared to the commercial line without any loss in yield potential or resistance to lodging. Genetic analysis of these lines identified several regions of their genomes that are associated with the improved resistance. The resulting lines are good candidates for germplasm releases and could be used as research materials for higher resolution genetic analysis of FER and FUM resistance.

Technical Abstract: Ear rots and mycotoxin contamination of grain in maize (Zea mays L.) pose a threat to food production and 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 lines with improved disease resistance without compromising grain yield or other agronomic traits. On average, the selected backcross lines and their topcross hybrids had less Fusarium ear rot and fumonisin content than their recurrent parent 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 two 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.