Deoxynivalenol glucosylation in durum wheat cultivars relation with FHB resistance under green house conditions

PALACIOS, S; ERAZO, J; CIASCA, B; PALAZZINI, J. M; LATTANZIO, V; CHULZE , S.N; FARNOCHI M. C.; TORRES, A. M

Beijing

Congreso; International Mycotoxin Conference 2014.Perspectives on the global prevention and control of mycotoxins; 2014

International Society of Mycotoxicology

Fusarium head blight (FHB) is a major fungal disease affecting wheat worldwide and it is caused mainly by Fusarium graminearum. The disease can severely reduce grain yield and quality and the infected grains could be contaminated with mycotoxins, especially deoxynivalenol (DON). This toxin is considered a virulence factor of the fungus, affecting the protein synthesis in plant cells. As a consequence, plants have developed detoxification processes including DON glucosylation to a less toxic compound, DON-3-β-D-glucoside (DON-3G) that is one of the most important ones. This ability has been proven to be linked to a quantitative trait locus previously reported to be associated to FHB resistance against spreading of Fusarium infection. The aim of this study was to evaluate the FHB resistance of 11 durum wheat cultivars, 7 commercial and 4 experimental cultivars, by introgression of genes, and their capacity to glucosylate DON to DON-3G under greenhouse conditions as part of an Argentinean breeding program. Two independent greenhouse experiments were performed. Each one consisted of four pots per cultivar, each with twelve plants. The wheat plants were point inoculated at anthesis with a mixture of conidia of two F. graminearum strains. Disease severity was assessed at 21 days after inoculation. No significant differences were found in severity (%) between experiment 1 and 2, then the results were pooled. The spikes were collected at harvest time, and whole ears were finely grounded for mycotoxin extraction. DON, its acetylated forms (3/15 ADON) and DON-3G were analyzed by LC-MS/MS. All wheat cultivars showed symptoms of the disease with severity ranging from 25 to 82% (P≤0.05). In addition, all samples showed DON contamination at levels ranging from 14 to 341 mg/kg and 3/15 ADON ranging from 0.29 to 5.21 mg/kg. There was no correlation between disease severity and DON content in the ears. Regarding the glucosylation capacity, all durum wheat cultivars were able to convert DON to DON-3G, the levels found ranged between 0.72 and 11.05 mg/kg and the relative concentrations varied between 0.4 and 9.9%. The concentration level of DON-3G resulted to be negatively correlated to the total DON content (DON + 3/15 ADON) (-0.76, P≤0.05). At high levels of total DON (DON + 3/15 ADON from 100 to 346 mg/kg) the level of glycosilation was negatively correlated with severity (-0.93, p≤0.05). The two cultivars (1 experimental and 1 commercial) showing low disease severity and DON contamination also showed the highest DON glucosylation capacity. Both cultivars are promising candidate for further studies in durum wheat breeding programs.