Regional differences in the composition of Fusarium head blight pathogens and mycotoxins associated with wheat in Mexico

Authors: CERON-BUSTAMANTE, M - Colegio De Postgraduados; Ward, Todd; LEYVA-MIR - University Of Chapingo; VILLASENOR-MIR, H - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP); AYALA-ESCOBAY, V - Colegio De Postgraduados; Kelly, Amy; Vaughan, Martha; McCormick, Susan; Cowger, Christina; NAVA-DIAZ, C - Colegio De Postgraduados

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2018
Publication Date: 3/13/2018
Citation: Ceron-Bustamante, M., Ward, T.J., Kelly, A.C., Vaughan, M.M., McCormick, S.P., Cowger, C., Leyva-Mir, S.G., Villasenor-Mir, H.E., Ayala-Escobar, V., Nava-Diaz, C. 2018. Regional differences in the composition of Fusarium head blight pathogens and mycotoxins associated with wheat in Mexico. International Journal of Food Microbiology. 273:11-19.

Interpretive Summary: Fusarium head blight (FHB) is a disease of cereals crops worldwide and a major food safety concern because FHB pathogens can contaminate grain with trichothecenes and other fungal toxins (mycotoxins). FHB is caused by a diverse set of fungal species that make different mycotoxins. Understanding which FHB species and toxin types are present in an area is key to disease and mycotoxin control programs. Information on FHB pathogen and mycotoxin diversity in Mexico has been extremely limited, but is needed to improve disease and mycotoxin control efforts across North America. To address this, we used a combination of DNA sequence-based methods and toxin analyses to characterize FHB isolates collected from wheat in Mexico. Among 116 Fusarium isolates, we identified nine previously described species and 30 isolates representing unnamed or potentially novel species. Significant regional differences in pathogen composition were observed, with F. boothii accounting for more than 90% of isolates from the Mixteca region in southern Mexico, whereas F. avenaceum and related members of the F. tricinctum species complex (FTSC) accounted for nearly 75% of isolates from the Highlands region in Central Mexico. Surprisingly, F. graminearum, which is the dominant FHB pathogen in other parts of North America, was not present among the isolates from Mexico. All of the F. boothii isolates, and some of the minor FHB species produced trichothecene mycotoxins. None of the FTSC isolates tested were able to produce trichothecenes, but many were able to produce other mycotoxins, including chlamydosporol and enniatins. These results provide new information on FHB pathogen and mycotoxin prevalence that can be used to develop regionally targeted disease and mycotoxin control programs that improve crop production and food safety.

Technical Abstract: Fusarium Head Blight (FHB) is a destructive disease of small grain cereals and a major food safety concern. Epidemics result in substantial yield losses, reduction in crop quality, and contamination of grains with trichothecenes and other mycotoxins. A number of different fusaria can cause FHB, and there are significant regional differences in the occurrence and prevalence of FHB pathogen species and their associated mycotoxins. Information on FHB pathogen and mycotoxin diversity in Mexico has been extremely limited, but is needed to improve disease and mycotoxin control efforts. To address this, we used a combination of DNA sequence-based methods and in-vitro toxin analyses to characterize FHB isolates collected from symptomatic wheat in Mexico during the 2013 and 2014 growing seasons. Among 116 Fusarium isolates, we identified five species complexes including nine named Fusarium species and 30 isolates representing unnamed or potentially novel species. Significant regional differences (P'<'0.001) in pathogen composition were observed, with F. boothii accounting for >90% of isolates from the Mixteca region in southern Mexico, whereas F. avenaceum and related members of the F. tricinctum species complex (FTSC) accounted for nearly 75% of isolates from the Highlands region in Central Mexico. F. graminearum, which is the dominant FHB pathogen in other parts of North America, was not present among the isolates from Mexico. F. boothii isolates had the 15-acetyldeoxynivalenol toxin type, and some of the minor FHB species produced trichothecenes, such as nivalenol, T-2 toxin and diacetoxyscirpenol. None of the FTSC isolates tested was able to produce trichothecenes, but many produced chlamydosporol and enniatin B.