Dynamics of Deoxynivalenol and Nivalenol Glucosylation in Wheat Cultivars Infected with Fusarium culmorum in Field Conditions─A 3 Year Study (2018-2020).

Fusarium head blight (FHB) caused by pathogenic species of Fusarium fungi is one of the most important diseases of cereal plants and a factor contributing to losses in plant production. The growth of FHB-associated species is often accompanied by biosynthesis of secondary metabolites─mycotoxins, which serve as a virulence factor. The aim of the study was to evaluate the ratios between deoxynivalenol (DON) and nivalenol (NIV) and their derivatives in the ears of six cultivars of winter wheat with varying resistance to FHB, taking into account a range of factors (weather conditions, location, cultivar, and year) after inoculation with Fusarium culmorum, during a 3 year field experiment, 2018-2020. The presence of toxins in the ears was measured within 21 days of inoculation. The toxins were found in the ears as soon as on the third day from the start of the experiment, whereas relative humidity higher than 80% was a decisive factor for FHB incidence. All wheat cultivars showed the ability to biotransform DON and NIV present in the ears to glucosides, that is, deoxynivalenol-3-glucoside (DON-3G) and nivalenol-3-glucoside (NIV-3G). The levels of these metabolites showed significant correlation with the levels of their basic analogues. In most cases, higher levels of DON and NIV in wheat ears and higher levels of their metabolites were observed, but the relative levels of DON-3G/DON and NIV-3G/NIV at relatively high levels of toxins were lower compared to the ear samples with relatively low toxin levels. The presented results are the first studies, which systematically correlate a variety of wheat cultivars with their extent to glucosylate trichothecenes.