– Modelling, reductive approaches and risk assessment with regards to the whole food chain
Fusarium fungi can cause Fusarium Head Blight and other diseases in cereals. In addition to reduced yield and germination capacity, different Fusarium spp. can produce different mycotoxins, including trichothecenes (deoxynivalenol (DON), T-2, HT-2), zearalenone and enniatins, which are toxic to humans and animals. In particular, DON, which is produced by Fusarium graminearum, has become more widespread with serious consequences for the cereal production and cereal industry. In some oat grain lots, high levels of HT-2/T-2-toxins caused by F. langsethiae have been additionally recorded.
The main goal of this project was to develop knowledge, methods and approaches that can contribute to reduced risk of mycotoxin contaminations in Norwegian cereals, and to evaluate health risks posed by mycotoxin exposures.
Cultivation practices that can influence Fusarium infection and mycotoxin development were studied using oats and spring wheat. The trials revealed increased inoculum potential in the fields after harrowing due to a substantial amount of plant debris on soil, compared to ploughing. Spring ploughing showed the same reduction in inoculum potential as autumn ploughing. The most common Fusarium species recorded in the plant debris were F. avenaceum and F. graminearum. We also detected F. langsethiae-DNA in low concentrations. Moreover, increased amounts of Fusarium-DNA, in particular F. graminearum, were detected in air samples after rainy periods. This is the first time that air dispersal of Fusarium has been determined in Norway. It was concluded that plant debris on soil could be an important source for fungi inoculum and that ploughing reduces the inoculum potential and risk of mycotoxin contamination in the field. However, air dispersal of F. graminearum from unploughed areas could cause infections in surrounding fields. Our data indicated that the occurrence of DON in oats does not correspond to the presence of HT2/T2-toxins. A phenology model that calculates the flowering stage in oats was developed (https://www.vips-landbruk.no/). It can be used by oats growers to decide on the time for fungicide treatment to control Fusarium infection.
We found a significant relationship between weather conditions and the extent of mycotoxin contamination in harvested grains. Growers guidelines regarding a reduced risk of mycotoxin contamination in cereals were updated as result of the project. We also have studied possibilities for increased variety resistance to fungal infections. A wide array of genotypes were tested in field trials. Clear varietal differences in the DON-content were demonstrated in oats, wheat and barley. The project results were fundamental for the release of new grain varieties in Norway in 2014. Our testing method demonstrated that genetic variation exists in the elite gene pool of oats with possibilities to achieve varieties with improved resistance in the short term. Furthermore, the testing of lines and crosses with German, Russian and North-American varieties led to the identification of promising resistance sources. The inheritance of DON resistance factors in oats was therefore further studied. Oats are most easily infected by fungi at flowering, leading to seed death or reduced germination due to fungal growth and toxin production, but also later infection time points can lead to reduced germination. Consequently, both toxins and germination potential should be measured in oat breeding trials.
We have developed an easy screening method for DON using Near InfraRed spectroscopy (NIR-calibration). It predicts the toxin content of a sample with an error of 3.16 ppm. This is adequate to identify the best third of the samples in breeding trials.
Endocrine disrupting effects from mycotoxin exposure, individually or in mixtures (including trichothecenes, zearalenone and its metabolites, and enniatins) obtained from F. graminearum extracts, were investigated by in number of in vitro assays such as in hormone-producing human and pig cells, and genetically modified hormone-signalling cells. Two mycotoxin mixtures were analysed in detail for their chemical composition by liquid chromatography-mass spectrometry. The first showed strong effects on hormone production and signalling, whereas the other had a more direct toxic effect on the cell models. Using subfractions of the mixtures, we were able to show that the hormone- disturbing effects were connected to zearalenone and its metabolites, whereas the cell toxic effects could be attributed to the presence of thrichothecenes. Individual mycotoxins were further studied by exploring the changes in proteins composition in the different cell models with the aim of determining mechanisms of action of the mycotoxins. Our observations indicated a need for increased awareness of possible adverse health effects in both humans and animals caused by the intake of food or feed contaminated with mycotoxins.
Cooperation project led by NIBIO, partners: NVI, Nofima, NMBU, Queens University Belfast (UK)
2010–2015
Publications:
Pasquali, M., Beyer, M., Logrieco, A., Audenaert, K., Balmas, V., Basler, R., … & Vogelgsang, S. (2016). A European database of Fusarium graminearum and F. culmorum trichothecene genotypes. Frontiers in microbiology, 7, 406.
Aamot, H. U., Ward, T. J., Brodal, G., Vrålstad, T., Larsen, G. B., Klemsdal, S. S., … & Hofgaard, I. S. (2015). Genetic and phenotypic diversity within the Fusarium graminearum species complex in Norway. European Journal of Plant Pathology, 142, 501-519.
Uhlig, S., Eriksen, G. S., Hofgaard, I. S., Krska, R., Beltrán, E., & Sulyok, M. (2013). Faces of a changing climate: Semi-quantitative multi-mycotoxin analysis of grain grown in exceptional climatic conditions in Norway. Toxins, 5(10), 1682-1697.
Busk, Ø. L., Frizzell, C., Verhaegen, S., Uhlig, S., Connolly, L., Ropstad, E., & Sørlie, M. (2012). Cytosol protein regulation in H295R steroidogenesis model induced by the zearalenone metabolites, α-and β-zearalenol. Toxicon, 59(1), 17-24.
Busk, Ø. L., Ndossi, D., Frizzell, C., Verhaegen, S., Uhlig, S., Eriksen, G., … & Sørlie, M. (2012). Changes in the proteome of the H295R steroidogenesis model associated with exposure to the mycotoxin zearalenone and its metabolites, α-and β-zearalenol. In Farm animal proteomics: Proceedings of the 3rd Managing Committee Meeting and 2nd Meeting of Working Groups 1, 2 & 3 of COST Action FA1002 (pp. 55-58). Wageningen Academic Publishers.