Glycosylated diterpenes associate with early containment of Fusarium culmorum infection across wheat (Triticum aestivum L.) genotypes under field conditions

Wheat (Triticum aestivum L.) is severely affected by head blight, a destructive disease caused primarily by Fusarium species, which reduces yield and contaminates grains with trichothecene mycotoxins that compromise food and feed safety worldwide. Mechanistic insights into host–pathogen interactions have largely emerged from controlled experimental settings, providing conceptual foundations under conditions of constrained genetic and environmental complexity. Resolving consistent, generalizable molecular patterns across diverse wheat genotypes within a large-scale, heterogeneous field study remains technically and methodologically challenging. Addressing this gap, we integrated quantitative mycotoxin profiling with untargeted metabolomics in a field experiment comprising 105 wheat genotypes deliberately inoculated with F. culmorum, with the goal of identifying molecular signatures of infection and containment under realistic agronomic conditions. Quantified deoxynivalenol (DON) concentrations provided a robust, continuous measure of infection intensity, enabling metabolite profiles to be related directly to pathogen activity beyond the limitations of symptom-based visual scoring. Consistent with established Fusarium trichothecene biosynthesis, sesquiterpene-derived metabolites closely tracked toxin accumulation, thereby recapitulating infection-associated metabolic patterns across the large-scale field study. Conversely, glycosylated diterpene conjugates were elevated under low toxin accumulation, linking their abundance to contained Fusarium pathogen activity and highlighting a largely underexplored aspect of wheat metabolism in host–pathogen interactions. Elucidating their biosynthetic origin, enzymatic interconversion, and regulatory context will be key to defining potential diterpene-associated defense processes across wheat genotypes.

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