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KEYNOTE LECTURE SESSION 2: SECONDARY METABOLITES – BIOCHEMISTRY, BIOSYNTHESIS, FEED AND FOOD SAFETY Metabolisation of deoxynivalenol in planta: Old and new compounds and their role in food safety F. Berthiller 1 , V. Nagl 1 , B. Kluger 1 , E. Varga 1 , A. Malachova 1 , C. Büschl 1 , H. Schwartz 1 , M. Lemmens 2 , R. Schuhmacher 1 , G. Adam 3 , R. Krska 1 University of Natural Resources and Life Sciences, Vienna, Austria (BOKU); 1 Department IFA-Tulln, Christian Doppler Laboratory for Mycotoxin Metabolism and Center for Analytical Chemistry, 3430 Tulln, Austria; 2 Department IFA-Tulln, Biotechnology in Plant Production, 3430 Tulln, Austria; 3 Department of Applied Genetics and Cell Biology, 1190 Vienna, Austria E-mail: franz.berthiller@boku.ac.at Fusarium mycotoxins are prone to be metabolised by growing plants on the field. The toxins can be chemically altered as part of the plants´ defense against fungal invasion and harmful xenobiotics, such as deoxynivalenol (DON), are more or less efficiently detoxified by various crops. The occurring metabolites, sometimes referred to as “masked mycotoxins”, can partly explain the mode of action of plant resistance. Furthermore, masked mycotoxins are also transferred into food. The possible hydrolysis of these metabolites back to their toxic parents during mammalian digestion raises concerns, as the total mycotoxin load of consumers might be underestimated. We employed a metabolomics LC-HR-MS based approach using in vivo stable isotopic labelling combined with a newly developed sophisticated software tool (MetExtract) to extract biological features originating from true metabolites. Flowering ears were inoculated with a mixture of non-labelled and 13 C labelled DON. Subsequent sample preparation, LC-HRMS measurements and data processing revealed a total of 57 corresponding peak pairs, which originated from ten metabolites. Besides DON and the known DON-3-glucoside (D3G), eight further DONbiotransformation products were found by the untargeted screening approach. These metabolites include two DON-glutathione forms and their processing products DON-Scysteine and DON-S-cysteinyl-glycine. In a recent survey, 374 beer samples from 38 countries were analysed for the presence of DON and D3G. In total, 77% of all beers contained DON, while even 93% contained D3G above the limit of detection. Average concentrations of all beers were 8.4 µg DON/L and 6.9 µg D3G/L. The highest contamination was detected in a pale beer from an Austrian microbrewery with 89 µg DON/L and 81 µg D3G/L. While the average contamination of beer is not of toxicological concern for moderate beer drinkers, heavy beer consumption considerably contributes to the overall DON intake. We have been able to describe the fate of DON-3-glucoside during digestion with in vitro and in vivo models. These results suggest that DON-3-glucoside is little bioavailable and readily hydrolysed to DON during digestion. In rats the liberated DON is partially converted to DOM-1 and excreted in faeces. DON is also taken up in the blood stream and metabolised to DON-glucuronide prior to excretion by urine. As the majority of D3G is excreted in faeces after hydrolisation, D3G in food and feed seems to have a significantly lower toxic equivalency compared to DON. Due to the differences regarding the anatomy and gut microbiota, the bioavailability and more importantly the metabolisation may be species dependent. Further studies, including other animal models are warranted. Keywords: masked mycotoxins, deoxynivalenol, deoxynivalenol-3-glucoside, digestion 39
SESSION 2: SECONDARY METABOLITES – BIOCHEMISTRY, BIOSYNTHESIS, FEED AND FOOD SAFETY Cellular adaptations for trichothecene biosynthesis in Fusarium graminearum J. Menke 1 , J. Weber 1,2 , K. Broz 1 , H. C. Kistler 1 1 Department of Plant Pathology, University of Minnesota, St. Paul, 55108, USA; 2 Molekulare Phytopathologie, Universität Hamburg D-22609 Germany E-mail: hckist@umn.edu Several species of the filamentous fungus Fusarium colonize plants and produce toxic small molecules that contaminate agricultural products, rendering them unsuitable for consumption. Among the most destructive of these species is F. graminearum, which causes disease in wheat and barley and often infests the grain with harmful trichothecene mycotoxins. Synthesis of these secondary metabolites is induced during plant infection or in culture in response to chemical signals. Our results show that trichothecene biosynthesis involves a complex developmental process that includes dynamic changes in cell morphology and the biogenesis of novel subcellular structures. Two cytochrome P-450 oxygenases (Tri4p and Tri1p) involved in early and late steps in trichothecene biosynthesis were tagged with fluorescent proteins and shown to co-localize to vesicles we named “toxisomes.” Toxisomes, the inferred site of trichothecene biosynthesis, dynamically interact with motile vesicles containing a predicted major facilitator superfamily protein (Tri12p) previously implicated in trichothecene export and tolerance. The immediate isoprenoid precursor of trichothecenes is the primary metabolite farnesyl pyrophosphate. Changes occur in the cellular localization of the isoprenoid biosynthetic enzyme HMG CoA reductase when trichothecene non-induced cultures are transferred either to trichothecene inducing or noninducing media. Initially localized in the cellular endomembrane system, HMG CoA reductase, upon trichothecene induction, increasingly is targeted to toxisomes. Metabolic pathways of primary and secondary metabolism thus may be coordinated and co-localized under conditions when trichothecene synthesis occurs. Keywords: mycotoxin, localization, secondary metabolism, isoprenoids 40
Page 1 and 2: Bordeaux EFS12 12 th European Fusar
Page 4: TABLE OF CONTENTS Welcome from the
Page 7: 4 SPONSORSHIP The 12 th European Fu
Page 11 and 12: 8 13:00 - 14:00 Lunch 14:00 - 15:00
Page 13 and 14: 10 Session 4: Genetics of Hosts - P
Page 15 and 16: 12 Thursday, May 16 th Session 6: F
Page 17 and 18: Evidence for birth-and-death evolut
Page 19 and 20: Future challenges of Fusarium and m
Page 21 and 22: P35 - Screening deoxynivalenol in o
Page 23 and 24: P76 - Fusarium verticillioides and
Page 25 and 26: P113 - Agronomic practices and risk
Page 28: ORAL PRESENTATIONS 25
Page 32 and 33: KEYNOTE LECTURE SESSION 1: FUSARIUM
Page 34 and 35: SESSION 1: FUSARIUM - GENETICS, GEN
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de Hoog G. S., 89, 114, 236 de Kler
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Ponts N., 33, 36, 82, 94, 104, 106,
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BOKU-University of Natural Resource
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touatisihem03@yahoo.fr He Xinyao In
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steve.oliver@bioc.cam.ac. uk Ortega
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Subramaniam Gopal Agriculture and A
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