Submitted to: European Journal of Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2013
Publication Date: 1/1/2014
Citation: Boutigny, A., Ward, T.J., Ballois, N., Iancu, G., Ioos, R. 2014. Diversity of the Fusarium graminearum species complex on French cereals. European Journal of Plant Pathology. 138(1):133-148. 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 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 cereals in France. 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 in France. However, significant regional differences in the frequencies of toxin types were observed, and F. graminearum with the NIV toxin type were a significant component of the population from the south of France. This is a significant concern for food safety and animal health, because NIV is considered more toxic than the 15ADON toxin type. In addition, a small percentage of the isolates from France were identified as species originating in the Southern hemisphere and may represent recent introductions of non-native pathogens. These results indicate the need to consider pathogen diversity in development of disease control and mycotoxin testing 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: Fusarium graminearum is an important pathogen causing Fusarium head blight (FHB) on wheat and barley and Gibberella ear rot (GER) on maize, and harvested grains often are contaminated with trichothecenes such as deoxynivalenol (DON) and nivalenol (NIV) that are a major health and food safety concern due to their toxicity to humans and farm animals. In this study, species identity and trichothecene toxin potential of 294 members of the Fusarium graminearum species complex (FGSC) collected from wheat, barley, and maize in France in 2011 was determined using a microsphere-based multilocus genotyping assay. F. graminearum sensu stricto species was predominant on all three hosts, but three isolates of F. cortaderiae and two isolates representing F. graminearum x F. boothii hybrids were also identified from maize. The 15-ADON trichothecene chemotype predominated on all three hosts, representing 94.7%, 87.8%, and 85.4% of the strains on barley, wheat, and maize, respectively. However, the NIV chemotype was found in 12.2% of the isolates collected from wheat and in 14.6% of the isolates collected from maize. Regional differences could be observed in the distribution of the 15-DON and NIV chemotypes, with the NIV producing-isolates being present at higher frequency (21.2%) in the south of France compared to the rest of the country (4.4%). Such information is critical because of the increased concern associated with NIV contamination of cereals. In addition, these results are needed to develop management strategies for FHB and GER in France and to improve understanding of the distribution and significance of FGSC diversity in Europe and worldwide.