Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2010
Publication Date: 2/16/2011
Publication URL: http://hdl.handle.net/10113/49263
Citation: Sampietro, D.A., Diaz, C.G., Gonzalez, V., Vattuone, M.A., Plopper, L.D., Catalan, C.N., Ward, T.J. 2011. Species diversity and toxigenic potential of Fusarium graminearum complex isolates from maize fields in northwest Argentina. International Journal of Food Microbiology. 145(1):359-364. Interpretive Summary: Fungal pathogens causing Fusarium head blight (FHB) produce toxins, such as nivalenol, that pose a significant threat to food safety and are common contaminants of wheat, barley, and other cereals. Contamination of grain with these toxins, and yield reductions caused by FHB infections threaten the economic viability of cereal production in some regions and impose a major burden on the world’s agricultural economy. Our previous analysis of FHB populations in North America indicated that a highly toxigenic population spread rapidly after being introduced into North America. The objective of this study was to improve understanding of global FHB diversity through analysis of FHB diversity in Argentina. This was undertaken in collaboration with scientists in Argentina and was supported through the Fulbright Foundation. Our results indicated that FHB species diversity in Argentina was greater than previously recognized, and suggested regional or host-specific differences that may contribute to difference in the toxins that are likely to be encountered. These results indicate the need to improve monitoring for nivalenol contamination of grain, and are critical to promoting food safety and cereal production through improved detection of mycotoxin-contaminated grain and through variety improvement efforts that account for the entire spectrum of pathogen and toxin types.
Technical Abstract: Members of the Fusarium graminearum species complex (Fg complex) are the causal agents of ear rot in maize and Fusarium head blight of wheat and other small grain cereals. The potential of these pathogens to contaminate cereals with trichothecene mycotoxins is a health risk for both humans and animals. A survey of ear rot isolates from maize collected in northwest Argentina recovered 66 isolates belonging to the Fg complex. A multilocus genotyping (MLGT) assay for determination of Fg complex species and trichothecene chemotypes was used to identify 56 of these isolates as F. meridionale and 10 isolates as F. boothii. F. meridionale was fixed for the nivalenol (NIV) chemotype, and all of the F. boothii isolates had the 15-acetyldeoxynivalenol (15ADON) chemotype. The results of genetic diversity analysis based on nine variable number tandem repeat (VNTR) loci supported the hypothesis of genetic isolation between F. meridionale and F. boothii, but also indicated little geographic substructure among populations of the dominant pathogen species, F. meridionale. This is the first study to indicate that F. meridionale and F. boothii may play a substantial role in the infection and trichothecene contamination of maize in Argentina. In addition, dominance of the NIV chemotype among Fg complex isolates from Argentina is unprecedented, and of significant concern to food safety and animal production.