Plant-Derived UDP-Glycosyltransferases for Glycosylation-Mediated Detoxification of Deoxynivalenol: Enzyme Discovery, Characterization, and In Vivo Resistance Assessment

Fungal infections of crops pose a threat to global agriculture. Fungi of the genus <i>Fusarium</i> cause widespread diseases in cereal crops. <i>Fusarium graminearum</i> reduces yields and produces harmful mycotoxins such as deoxynivalenol (DON). Plants mitigate DON toxicity through glucose conjugation mediated by UDP-glycosyltransferases (UGTs), forming deoxynivalenol-3-<i>O</i>-glucoside (DON-3-Glc). Few such UGTs have been identified, predominantly from <i>Fusarium</i>-susceptible crops. Given that the presence of this activity in diverse plants and across broader UGT subfamilies and groups was underexplored, we screened a library of 380 recombinant plant UGTs and identified and characterized eight novel enzymes glycosylating DON in vitro. Among these, <i>Zj</i>UGT from <i>Ziziphus jujuba</i> stood out with the highest activity, showing an apparent <i>k</i>_cat of 0.93 s^-1 and <i>k</i>_cat/<i>K</i>_m of 2450 M^-1 s^-1. Interestingly, four enzymes produced primarily a novel, still uncharacterized glucoside. Furthermore, we evaluated the in vivo resistance provided by these UGTs when expressed in a DON-sensitive yeast strain. At least six of the novel UGTs conferred some level of resistance, allowing growth at concentrations of up to 120 mg/L of DON. This study contributes to potential strategies to enhance DON resistance in cereal crops in the future.