Mycotoxin contamination in Norw. food and feed - modelling, reductive appro. and risk assesment w/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), zearalenon 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 oats grain lots also high levels of HT-2/T-2-toxins caused by F. langsethiae, have been 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 practice that can influence on the Fusarium infection and mycotoxin development was studied in 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. Increased amounts of Fusarium-DNA, in particular F. graminearum, were detected in air samples after rainy periods. This is the first report of air dispersal of Fusarium in Norway. It was concluded that plant debris on soil might be an important source of inoculum and that ploughing reduces the inoculum potential and the risk of mycotoxin contamination in the field. However, air dispersal of F. graminearum from unploughed areas might cause infection and DON development in surrounding fields. Our data indicate that development of DON in oats not corresponds with the risk of HT2/T2-toxins. A phenology model that calculates the flowering stage in oats has been developed (vips-landbruk.no). It can be used by oats growers to decide on the time for fungicide treatment to control Fusarium. We found a significant relationship between weather conditions and mycotoxin contaminations of harvested grains. A growers guidelines (dyrkingsveiledning) on how to reduce risk of mycotoxin development in cereals, was updated. Possibilities for increased variety resistance were an important part for the project. A wide array of genotypes was tested in field trials at UMB/NMBU, and from 2011 the testing capacity was increased considerably when Graminor also established a similar disease nursery (for own expenses). Clear varietal differences in DON-content were demonstrated in oats, wheat and barley. The project results were important when new varieties were released in 2014. Our testing method demonstrates that genetic variation exists in the elite gene pool of oats with possibilities to achieve varieties with improved resistance in the short term. Testing of lines and crosses with German, Russian and North-American lines has also identified promising resistance sources. Inheritance of DON resistance in oats was studied. Oats are most easily infected at flowering, when seeds die or have reduced germination due to fungal infection and toxins. Later infections can also lead to reduced germination. In practice, both toxins and germination should be measured in breeding trials. Through collaboration with Nofima we have developed a cheap screening method for DON by 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. Hormone disturbing effects of mycotoxins, individually or in mixtures (incl trichothecenes, zearalenon, and its metabolites, and enniatins), based on extracts of from F. graminearum, were investigated by in vitro methods. NVH/NMBU used laboratory models based on hormone-producing cells from human or pig origin. Queens University Belfast (Northern Ireland) used genetic modified cells to study the effects on hormone signaling. Two such mixtures were analyzed in detail by VI for their chemical composition. One mixture had strong effects on hormone production and signaling, whereas the other one had a more direct toxic effect on the cell models. Using subfractions of these mixtures, generated by VI, it could be concluded that the hormone disturbing effects were mainly due to the content of zearalenone and its metabolites, whereas the cell toxic effects could be could be attributed to the presence of thrichothecenes. Individual mycotoxins where further studied at UMB/NMBU exploring overall changes in proteins in the cell models, and thus to determine mechanisms of action of these mycotoxins. The observations indicate 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.

The main goal of this project is to reduce the risk of mycotoxin contamination in Norwegian food and feed, and to evaluate health risks posed by mixed exposure scenarios in humans and animals. The project (2010-2013) is planned organised in three work pac kages (WPs). WP A will focus on measures to reduce the risk of development of Fusarium and mycotoxins in Norwegian oats and spring wheat. Experiments will be conducted to clarify the effect of different tillage regimes on development of Fusarium and mycot oxins in plant residues and in grains. We aim to identify field characteristics (terrain, soil type, etc.) that are responsible for the local and regional differences observed. The accuracy of prediction models will be increased by, in addition to weather data, including data on tillage systems, crop rotation and field characteristics. WP B will focus on methods and germplasm for breeding resistant cultivars, the most cost-effective long-term measure for the prevention of mycotoxins through disease screen ing nurseries in wheat and oats. In wheat, well-characterized genetic resistance and selection criteria exist. In oats, much work remains with regard to genetic variation and resistance criteria. The project will address both aspects by defining infection parameters and by crossing German low-toxin cultivars with Norwegian genotypes. A major hurdle is the cost of mycotoxin analyses. The project will use field and chemical data to develop a near-infrared calibration to be used in disease screening nurserie s. WP C will assess health risks following exposure to complex mixtures of mycotoxins using animal and human in vitro models. A bioassay-base fractionation approach will be used to detect activity of mycotoxin mixtures, followed by chemical characterizati on of active fractions. "Omics" analysis and mechanistic studies should lead to better understanding of working mechanisms and lead to biomarkers for mycotoxin exposure.