Poster

Briana K. Whitaker ¹, Nicholas Rhoades ², Susan McCormick ¹, Guixia Hao ¹
1. USDA, Agricultural Research Service, National Center for Agricultural Utilization Research, Mycotoxin Prevention & Applied Microbiology Unit, 1815 N University St., Peoria, IL 61604 USA
2. ORISE Fellow, USDA, Agricultural Research Service, National Center for Agricultural Utilization Research, Mycotoxin Prevention & Applied Microbiology Unit, 1815 N. University St., Peoria, IL 61604 USA
Corresponding Author: Briana K. Whitaker, briana.whitaker@usda.gov

Whitaker, Briana

briana.whitaker@usda.gov

Microbe-leveraged strategies are increasingly advocated as part of integrated disease control in agricultural systems. However, our understanding of plant-pathogen infection stages on the microbiome is generally limited to pattern- and effector-triggered immunity in most pathosystems. The wheat-Fusarium head blight (FHB) system thus presents an opportunity to study additional stages of infection, such as the release of the virulence factor deoxynivalenol (DON) by pathogenic Fusarium graminearum. In this study, we determined how the wheat spike microbiome responds to F. graminearum infection relative to the presence or absence of DON. Spring wheat plants were exposed to microbiome inoculum in the field, then infected at maturity with either a DON-producing wild type or a DON-deficient mutant. We found that fungal diversity and community structure were consistently reduced by F. graminearum infection, regardless of the presence or absence of DON. By contrast, bacterial diversity and community structure showed more context-dependent responses to F. graminearum treatment across experimental conditions. Differential abundance analysis further highlighted distinct responses between microbial kingdoms. Specifically, fungi tended to be depleted in the presence of F. graminearum relative to controls, while bacteria tended to be enriched. Six fungi (ex. Nigrospora, Neoascochyta), but no bacteria, were consistently depleted from F. graminearum treatments, potentially indicating a negative response to both F. graminearum and DON. On the other hand, four bacteria (ex. Acinetobacter), but no non-Fusarium fungi, were consistently enriched in both F. graminearum treatments. Additionally, some microbes (2 fungi and 4 bacteria) were enriched in the DON-deficient treatments but depleted from the DON-producing wild type treatment. Lastly, direct gradient analyses demonstrated that both bacterial and fungal communities were impacted by DON and F. graminearum biomass in different ways. Collectively, these results indicate that the virulence factor DON has a distinct impact on the presence and abundance of microbial taxa in the wheat spike, independent to the effect of colonization by F. graminearum. Future work could develop microbe-leveraged disease control strategies based on specific microbial responses to DON-induced immune stimulation versus F. graminearum antagonism directly.

© Copyright 2026 by individual authors. All rights reserved. No part of this abstract or paper publication may be reproduced without prior permission from the applicable author(s).