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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #429779
Research Project: Aflatoxin Control through Identification of Intrinsic and Extrinsic Factors Governing the Aspergillus Flavus-Corn Interaction

Location: Food and Feed Safety Research

Title: Differential corn kernel infection and metabolism by two Aspergillus flavus strains

Author
item Sweany, Rebecca
item Gilbert, Matthew
item THIBODEAUX, YENJIT - Oak Ridge National Laboratory
item MELGUIZO, CLARA - Complutense University Of Madrid (UCM)
item Lebar, Matthew
item BRANSTAD-SPATES, EMILY - Oak Ridge National Laboratory

Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2025
Publication Date: 12/17/2025
Citation: Sweany, R.R., Gilbert, M.K., Thibodeaux, Y.R., Melguizo, C., Lebar, M.D., Branstad-Spates, E.H. 2025. Differential corn kernel infection and metabolism by two Aspergillus flavus strains. Plant Pathology. Available https://doi.org/10.1111/ppa.70106.
DOI: https://doi.org/10.1111/ppa.70106

Interpretive Summary: Contamination of corn with acutely toxic and carcinogenic aflatoxins can result in poisonings and death in humans, livestock, pets and wildlife. Understanding the biology of the causal fungal agent Aspergillus flavus is crucial to devising better strategies to manage and minimize aflatoxin contamination of corn. We examined the infection process of two Aspergillus flavus strains. We demonstrated that genetically distinct strains infect at different rates and produce different levels of aflatoxin. We also demonstrated they result in different levels of kernel rot and nutrient loss. This suggests that when corn lines are evaluated for resistance to A. flavus, it must be determined if they are resistant to multiple corn isolates.

Technical Abstract: Aspergillus flavus infection of corn is a major agronomic concern due to contamination with acutely toxic and carcinogenic aflatoxins. A. flavus populations are very diverse, however more than 70% of corn isolates produce large sclerotia. There is limited research investigating corn infection by different A. flavus strains. This study tracked corn kernel infection by a small sclerotial strain, Af70-GFP and a large sclerotial strain, Tox4-RFP, which were engineered to express green and mCherry red fluorescent proteins, respectively. Fluorescence, aflatoxin and A. flavus DNA were assessed to track fungal infection. Near-infrared light spectroscopy was used to measure kernel nutrient composition. Af70-GFP was able to establish kernel infection earlier than Tox4-RFP as measured by fluorescence and ddPCR; AF70-GFP also produced aflatoxin earlier in infection and in greater quantities. Protein, fat and starch content decreased with longer infection. Af70-GFP infection resulted in reduction in kernel starch content, whereas Tox4-RFP reduced protein and fat content more than Af70-GFP. Increased starch metabolism likely resulted in greater aflatoxin production by Af70-GFP. This research suggests that fungal strains may differ in their abilities to infect corn. Hence, a greater diversity of A. flavus should be assessed in future studies for their virulence to assist in improving biocontrol and resistance technologies.