Invited Presenter

Gerit Bethke ¹, Sean O’Mara ¹, Yadong Huang ¹, Yinjie Qiu ², Franz Berthiller ³, and Gary J. Muehlbauer ¹
1. University of Minnesota, Department of Agronomy and Plant Genetics, St. Paul, MN
2. University of Minnesota, Minnesota Supercomputing Institute, Minneapolis, MN
3. University of Natural Resources and Life Sciences, Department of Agrobiotechnology, Vienna, Tulln 3430, Austria
Corresponding Author: Gary Muehlbauer, muehl003@umn.edu

Muehlbauer, Gary

muehl003@umn.edu

Fusarium head blight (FHB), caused by Fusarium graminearum, significantly reduces barley and wheat yield and grain quality. The pathogen produces trichothecene mycotoxins such as deoxynivalenol (DON), which act as virulence factors during infection. All tested barley accessions display only type II resistance, suggesting limited natural genetic variation for this trait. Meta-analyses of barley genetic mapping studies indicate that most FHB resistance QTL are associated with morphological or physiological traits, implying that observed resistance often results from escape mechanisms rather than true genetic resistance. We identified a barley UDP-glucosyltransferase gene, HvUGT13248, that detoxifies DON by conjugating it to DON-3-O-glucoside (D3G). Barley lines overexpressing HvUGT13248 exhibit reduced FHB severity and enhanced DON tolerance through rapid conversion of DON to D3G. Mutations in the enzyme’s active site compromise this detoxification capacity, resulting in reduced type II resistance and increased DON sensitivity, demonstrating that HvUGT13248 is required for type II resistance. Resequencing of diverse barley germplasm revealed that HvUGT13248 is highly conserved, with few nonsynonymous substitutions that do not alter enzyme function. Functional assays using fungal strains producing a range of trichothecene toxins showed that HvUGT13248 provides broad-spectrum detoxification and resistance. RNA-seq analysis of the HvUGT13248 mutant compared to a wildtype sibling showed that overall gene expression was earlier and greater in the mutant; however, fungal trichothecene genes were more highly expressed in the wildtype genotype. Together, these findings demonstrate that HvUGT13248 confers type II resistance in barley through the detoxification of multiple trichothecene mycotoxins.

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