Resistance to gibberella ear rot in maize: Potential mechanisms and breeding strategies

F. graminearum, the causal agent of Gibberella ear rot in corn, is one of the most dangerous plant-pathogenic fungi that causes disease on maize. F. graminearum deposits the mycotoxins deoxynivalenol (DON) and zearalenone (ZEA) which can cause emesis, food refusal, and cancer in humans and animals when consumed. The United States, Canada, and Europe have systems and checks in place to manage mycotoxin exposure; while regions that lack this infrastructure are chronically exposed to mycotoxins as part of their diet. Outbreaks are possible everywhere despite even the best management practices. Breeding has resulted in increased resistance to fungal colonization, which indirectly decreases DON levels in grain. However, highly resistant hybrids have yet to be released. Additionally, DON can be present in grain without visual symptoms, emphasizing the need to target both traits in breeding programs. A final facet in the complex maize-F. graminearum system is the environmental variability associated with the disease. Within the same growing region disease pressure and mycotoxin presence can vary drastically between growing seasons. Wheat, another host for F. graminearum, has been extensively studied. By comparing the two systems we can gain insight into potential mechanisms of resistance. As a complement to ongoing breeding efforts, continued screening of diverse germplasm, identification of potential regions for further follow-up, and an exploration of potential mechanisms underlying disease resistance will improve understanding of the disease. Using a diversity panel (n = 318) I identified multiple markers associated with GER resistance, mycotoxin accumulations, changes in hydroxycinnamic acid content, and pericarp thickness. Several metabolic pathways and candidate genes were associated with the phenylpropanoid pathway and cell wall reinforcement. Using disease severity values from the diversity panel I selected three near-isogenic line populations to identify meaningful regions associated with disease severity. Using near-isogenic lines and quantitative trait locus mapping, I identified a large region on chromosome 5 in all three populations. Furthermore, we observed moderate correlations between GER severity and resistance to northern corn leaf blight, suggesting the potential for multiple disease resistance across plant organs. Finally, I examined the presence of multiple ear rots and mycotoxins in two hybrid panels that were screened across North America. As the global climate changes, it is important to examine any shifts in disease pressure and mycotoxin accumulation caused by plant pathogens. Regardless of guidelines and testing practices outbreaks can have devastating social and economic impacts. In conclusion, ear rots and their accompanying mycotoxins are prevalent in maize grown in the United States, and it is critically important to work to improve host resistance so that farmers have effective management strategies.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Crop Sciences

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Lipps, Sarah J.

Contributors dc:contributor

• Jamann, Tiffany
• Bohn, Martin
• Rutkoski, Jessica
• Butts-Wilmsmeyer, Carolyn

• quantitative disease resistance
• Gibberella ear rot
• Fusarium graminearum
• Fusarium head blight
• maize
• zea mays
• environmental covariates
• sliding window
• Fusarium ear rot
• Fusarium verticillioides
• Aspergillus ear rot
• Aspergillus flavus
• multiple disease resistance
• near-isogenic lines
• mycotoxins
• dexoynivalenol
• zearalenone

Statement dc:rights

• Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129714

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129714