Submitted to: International Journal of Food Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/23/2013
Publication Date: 7/1/2013
Citation: Umpierrez-Failache, M., Garmendia, G., Pereyra, S., Rodriquez-Haralambides, A., Ward, T.J., Vero, S. 2013. Regional differences in species composition and toxigenic potential among Fusarium head blight isolates from Uruguay indicate a risk of nivalenol contamination in new wheat production areas. International Journal of Food Microbiology. 166(2013):135-140. Interpretive Summary: Fungi within the Fusarium graminearum species complex (FGSC) are responsible for economically destructive diseases of wheat, barley and other cereals world-wide. In addition, these fungi contaminate grain with are trichothecene mycotoxins that pose a significant threat to food safety and animal health. As part of a project to establish a global picture of FGSC diversity, we determined the prevalence of FGSC species and toxins associated with diseased wheat in Uruguay. Fusarium graminearum and the 15ADON toxin type, which are the most common FGSC species and toxin types found in the United States, accounted for more than 85% of the isolates collected from diseased wheat. However, F. asiaticum and the NIV toxin type predominated in new wheat production areas in eastern Uruguay, where rice production is common. These results are similar to those we recently published indicating that F. asiaticum and the NIV toxin type may have been introduced into a major rice-producing region of the United States. This is a significant concern for food safety and animal health, because NIV is considered more toxic than the 15ADON toxin type. Significant differences in aggressiveness and fungicide sensitivity were also observed between different species and toxin types indicating the need to consider this pathogen diversity in development of disease control programs. As such, the results reported here are critical to promoting food safety and cereal production through improved detection of novel FGSC pathogens and through plant quarantine and variety improvement efforts that account for the entire spectrum of FGSC pathogens and toxin types.
Technical Abstract: Members of the Fusarium graminearum species complex (FGSC) are the primary cause of Fusarium head blight (FHB) of wheat, and frequently contaminate grain with trichothecene mycotoxins that pose a serious threat to food safety and animal health. The species identity and trichothecene toxin potential of 151 FGSC isolates collected from wheat in Uruguay was determined via multilocus genotyping. Although F. graminearum with the 15ADON trichothecene type accounted for 85% of the isolates examined, five different FGSC species and all three trichothecene types were identified in this collection. This is the first report of F. asiaticum, F. brasillicum, F. cortaderiae, and F. austroamericanum from Uruguay. In addition, we observed significant (P < 0.001) regional differences in the composition of FGSC species and trichothecene types within Uruguay. Isolates of F. graminearum with the 15ADON type were the most prevalent in western provinces (95%), while F. asiaticum (43%) and the NIV type (61%) predominated in the new wheat production zone in Cerro Largo along Uruguay’s eastern border with Brazil. F. graminearum isolates (15ADON type) were significantly (P < 0.005) more aggressive on wheat than were isolates from the other species examined (NIV or 3ADON types). However, F. graminearum isolates (15ADON type) were significantly (P < 0.05) more sensitive to tebuconazole than isolates from other species (NIV type). These results document substantial heterogeneity among the pathogens responsible for FHB in Uruguay. In addition, the regional predominance of the NIV trichothecene type is of significant concern to food safety and indicates that additional monitoring of nivalenol levels in grain may be required.