Submitted to: Canadian Journal of Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/24/2009
Publication Date: 6/2/2010
Publication URL: http://dx.doi.org/10.1080/07060661003740231
Citation: Gilbert, J., Clear, R.M., Ward, T.J., Gaba, D., Tekauz, A., Turkington, T.K., Woods, S.M., Nowicki, T., O Donnell, K. 2010. Relative aggressiveness and production of 3- or 15-acetyl deoxynivalenol and deoxynivalenol by Fusarium graminearum in spring wheat. Canadian Journal of Plant Pathology. 32(2):146.152. Interpretive Summary: Fungal pathogens within the Fusarium graminearum species complex cause diseases of cereal crops worldwide, including Fusarium head blight (FHB) of wheat and barley. These diseases result in billion dollar losses to agriculture each year. In addition, these fungi contaminate grain with trichothecene mycotoxins that pose a serious threat to animal health and food safety. Recently, we demonstrated that FHB populations were changing dramatically across North America. In order to better understand the impact of these population shifts on plant production and food safety we tested a strains representing the previously dominant (15ADON population) and novel (3ADON) populations for relative aggressiveness and toxin production on wheat. The results indicate that infection of a susceptible wheat variety by members of the novel 3ADON population results in grain that is more heavily contaminated with trichothecene toxins. However, the 3ADON and 15ADON isolates produced essentially the same amount of toxin when infecting moderately resistant wheat varieties. These results suggest that as the percentage of 3ADON strains increases, DON levels in cereals are likely to increase in epidemic years. However, the wider use of moderately resistant cultivars could help to mitigate the food safety impact of changes in the pathogen population.
Technical Abstract: Fusarium graminearum Schwabe is the principal cause of fusarium head blight in North America, a disease that has cased severe losses in yield and quality of cereals. In North America, the vast majority of F. graminearum isolates produce either 3- or 15- acetyl deoxynivalenol (ADON) in addition to DON. Until recently, 15-ADON isolates predominated, but a rapid shift from 15-ADON to 3-ADON producers in Canada and north central USA has been documented. In order to better understand the impact of these population shifts we tested a total of 58 3ADON and 15ADON strains for relative aggressiveness and toxin production on two Canadian spring wheat cultivars, ‘Roblin’ (susceptible) and ‘5602 HR’ (moderately resistant). In Experiment 1, 18 strains, 3 producing 15-ADON and 3 producing 3-ADON from each of the Canadian provinces of Manitoba, Saskatchewan and Alberta, were tested using spray inoculation. In Experiment 2, 40 isolates from Manitoba, 20 producing 15-ADON and 20 producing 3-ADON, were tested using point inoculation. There were no significant differences in aggressiveness among strains based either on origin or toxin type. Importantly, toxin analysis by gas chromatography/mass spectrometry of seeds from inoculated heads indicated that the 3-ADON strains produced significantly more DON than the 15-ADON strains in ‘Roblin’ following both spray and point inoculation and in ‘5602HR’ after point inoculation. DON levels following point inoculation by 15-ADON strains were similar in the two cultivars. In addition, 15-ADON strains from Alberta produced less DON than 15-ADON strains from Manitoba and Saskatchewan. Further, consistently more of the acetylated derivative 15-ADON was produced by 15-ADON strains than 3-ADON by 3-ADON strains. These results suggest that as the percentage of 3-ADON strains in Canada increases, DON levels in cereals are likely to increase in epidemic years.