Transgenic Wheat Expressing a Barley UDP-Glucosyltransferase Detoxifies Deoxynivalenol and Provides High Levels of Resistance to Fusarium graminearum

Abstract

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, is a devastating disease of wheat that results in economic losses worldwide. During infection, F. graminearum produces trichothecene mycotoxins, including deoxynivalenol (DON), that increase fungal virulence and reduce grain quality. Transgenic wheat expressing a barley UDP-glucosyltransferase (HvUGT13248) were developed and evaluated for FHB resistance, DON accumulation, and the ability to metabolize DON to the less toxic DON-3-O-glucoside (D3G). Point-inoculation tests in the greenhouse showed that transgenic wheat carrying HvUGT13248 exhibited significantly higher resistance to disease spread in the spike (type II resistance) compared with nontransformed controls. Two transgenic events displayed complete suppression of disease spread in the spikes. Expression of HvUGT13248 in transgenic wheat rapidly and efficiently conjugated DON to D3G, suggesting that the enzymatic rate of DON detoxification translates to type II resistance. Under field conditions, FHB severity was variable; nonetheless, transgenic events showed significantly less-severe disease phenotypes compared with the nontransformed controls. In addition, a seedling assay demonstrated that the transformed plants had a higher tolerance to DON-inhibited root growth than nontransformed plants. These results demonstrate the utility of detoxifying DON as a FHB control strategy in wheat.

A Brachypodium UDP-Glycosyltransferase Confers Root Tolerance to Deoxynivalenol and Resistance to Fusarium Infection

“…These enzymes mediate the transfer of glycosyl residues from nucleotide sugars to acceptor aglycones, thus regulating properties of the acceptors such as their bioactivity, water solubility, and transport within the cell and throughout the organism (Gachon et al, 2005 Poppenberger et al, 2003), barley (Hv13248; Schweiger et al, 2010;Shin et al, 2012), wheat (TaUGT3 [Lulin et al, 2010] and TaUGT12887 [Schweiger et al, 2013b]), and Brachypodium distachyon (Bradi5g03300; Schweiger et al, 2013a). Conjugation of DON into D3G by the corresponding UGTs was only shown in heterologous species, such as Saccharomyces cerevisiae (Schweiger et al, 2010(Schweiger et al, , 2013a(Schweiger et al, , 2013b, Arabidopsis (Poppenberger et al, 2003;Shin et al, 2012), or wheat (Li et al, 2015). In that most recent study, heterologous overexpression of the barley UGT gene Hv13248 in wheat varieties susceptible to FHB was shown to result in higher resistance in both greenhouses and field conditions (Li et al, 2015).…”

“…Conjugation of DON into D3G by the corresponding UGTs was only shown in heterologous species, such as Saccharomyces cerevisiae (Schweiger et al, 2010(Schweiger et al, , 2013a(Schweiger et al, , 2013b, Arabidopsis (Poppenberger et al, 2003;Shin et al, 2012), or wheat (Li et al, 2015). In that most recent study, heterologous overexpression of the barley UGT gene Hv13248 in wheat varieties susceptible to FHB was shown to result in higher resistance in both greenhouses and field conditions (Li et al, 2015). However, that study only investigated DON conjugation after direct application of the toxin and not during infection by F. graminearum, thereby preventing the establishment of a direct correlation between the in planta conjugation of DON into its glucoside during infection and resistance to the fungal pathogen (Li et al, 2015).…”

“…In that most recent study, heterologous overexpression of the barley UGT gene Hv13248 in wheat varieties susceptible to FHB was shown to result in higher resistance in both greenhouses and field conditions (Li et al, 2015). However, that study only investigated DON conjugation after direct application of the toxin and not during infection by F. graminearum, thereby preventing the establishment of a direct correlation between the in planta conjugation of DON into its glucoside during infection and resistance to the fungal pathogen (Li et al, 2015).…”

Deoxynivalenol resistance as a component of FHB resistance

“…Transgenic Arabidopsis lines expressing a barley UGT (HvUGT13248) showed enhanced tolerance to DON toxicity (Shin et al 2012). Li et al (2015) went on to demonstrate that the expression of this barley gene in transgenic wheat rapidly and efficiently conjugated DON to D3G and generally reduced the severity of FHB under field conditions. The model cereal Brachypodium distachyon encodes two homologs of HvUGT13248, and the encoded proteins were shown to convert DON to D3G when expressed in yeast (Schweiger et al 2013a).…”

Genetic Engineering and Sustainable Crop Disease Management: Opportunities for Case-by-Case Decision-Making

“…Significantly less disease development was observed in American chestnut trees transformed with a wheat gene coding for the production of the degradative enzyme, oxalate oxidase [103]. As another example, a toxin-degrading enzyme encoded by a barley gene was transformed into wheat, resulting in resistance in the wheat to the highly destructive disease, Fusarium head blight [104]. In both examples, the gene constructs used included a viral promotor and a bacterial selectable marker, so in their present configuration, these GE crops clearly qualify as transgenic.…”