Poster # 309

Gerit Bethke ¹, Sean O’Mara ¹, Yadong Huang ¹, Yinjie Qiu ², Herbert Michlmayr ³, Franz Berthiller ⁴, Gary 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, Vienna (BOKU), Institute of Microbial Genetics (IMIG), Tulln, Austria
4. University of Natural Resources and Life Sciences, Vienna (BOKU), Institute of Bioanalytics and Agro-Metabolomics, Tulln, Austria
Corresponding Author: Gary Muehlbauer, muehl003@umn.edu

Muehlbauer, Gary

muehl003@umn.edu

Fusarium head blight (FHB) is a complex disease affecting wheat and barley. Finding stable resistance to infection and disease spread has proven a difficult endeavor. Our lab has focused on the role of a barley UDP-glucosyltransferase, HvUGT13248, in the glycosylation and subsequent detoxification of the major FHB mycotoxin deoxynivalenol (DON). Here, we summarize our results across multiple experiments that aimed to understand the role of HvUGT13248 in the resistance of wheat and barley to FHB. We utilized a nonfunctional mutant allele of HvUGT13248 to show that type I resistance to FHB is unaffected by the loss of this enzyme. The infection rate and maximum number of infection points per plant were unchanged in barley plants lacking a functional HvUGT13248. Disease spread was greatly increased in the mutant line, confirming the role of HvUGT13248 in type II resistance. To expand our understanding of the substrate specificity of HvUGT13248 we observed the increased spread of Fusarium graminearum chemotypes producing 15-acetyl-DON, 3-acetyl-DON, Nivalenol and NX2 and reduced glycosylation ratios against those toxins in the HvUGT13248 mutant compared to wild-type plants. Similarly, overexpression of HvUGT13248 in the wheat cultivar ‘Bobwhite’ resulted in increased and faster glycosylation of DON, 3-acetyl-DON, 15-acetyl-DON and NX2 toxins in the transgenic compared to wild-type plants. When HvUGT13248 was constitutively expressed in the wheat cultivar ‘Rollag’ in the presence or absence of the FHB1 resistance QTL, HvUGT13248 provided significant resistance to FHB spread. This effect was as strong and less variable than the resistance provided by the native FHB1 resistance QTL. RNA-seq analysis of the HvUGT13248 mutant and wildtype plants indicated a more rapid and substantial change in gene expression in the mutant compared to wildtype. Furthermore, a weighted gene co-expression network analysis identified a large module of genes with similar expression patterns, which was enriched for genes associated with defense, metabolite processing, protein and macromolecule modification, and response to stimuli. This module was similarly more rapidly and highly expressed in the HvUGT13248 mutant compared to wildtype during infection with F. graminearum. Conversely, differential gene expression analysis of F. graminearum genes revealed that the genes involved in trichothecene biosynthesis were more highly expressed when inoculated in wildtype barley plants with a functional HvUGT13248.

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