Mycotoxin glucosylation in commercial wheat varieties: Impact on resistance to Fusarium graminearum under laboratory and field conditions

Fusarium head blight (FHB) is a devastating disease on small cereal crops and is primarily caused by Fusarium graminearum. FHB typically is associated with a contamination of the infected grains with mycotoxins, which can act as virulence factors for the advancing fungus. Some wheat plants have evolved a typical resistance designated Fhb1 resistance, which is associated with a glucosyltransferase function, capable of detoxifying the deposited deoxynivalenol (DON), a mycotoxin abundantly produced by F. graminearum. However, the resulting 'masked mycotoxin', deoxynivalenol-3-glucoside (DON-3G), may be metabolized in the digestive tract of animals, releasing the native toxin anew. The present study aims to assess the glucosylation capacity in the Belgian commercial wheat pool and to determine the importance of DON glucosylation in the complex background of natural field circumstances. Clear indications were found that several Belgian commercial wheat cultivars, to some extent, do possess a glucosyltransferase function capable of detoxifying significant amounts of DON. However, the level of glucosylation in the field did not correlate well with disease severity. The present research provides the first large-scale assessment of this glucosylation capacity in Belgian commercial wheat cultivars.