Five-year survey uncovers extensive diversity and temporal fluctuations among fusarium head blight pathogens of wheat and barley in Brazil

Authors: PEREIRA, C - University Of Maringa; Ward, Todd; DEL PONTE, E - Universidade Federal De Vicosa; MOREIRA, G - Universidade Federal De Vicosa; Busman, Mark; McCormick, Susan; FEKSA, H - Agrária Foundation For Agricultural Research; DE ALMEIDA, J - Agrária Foundation For Agricultural Research; TESSMANN, D - University Of Maringa

Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2020
Publication Date: 10/8/2020
Citation: Pereira, C.B., Ward, T.J., Del Ponte, E.M., Moreira, G.M., Busman, M., McCormick, S.P., Feksa, H.R., De Almeida, J.L., Tessmann, D.J. 2020. Five-year survey uncovers extensive diversity and temporal fluctuations among fusarium head blight pathogens of wheat and barley in Brazil. Plant Pathology. 70(2):426-435. https://doi.org/10.1111/ppa.13289.
DOI: https://doi.org/10.1111/ppa.13289

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 a variety of fungal toxins (mycotoxins). FHB is caused by a diverse set of fungal species that make different mycotoxins, making it difficult to determine which mycotoxins may be present in FHB-symptomatic grain. As part of an international cooperative project to improve food safety through enhanced mycotoxin monitoring, we determined the prevalence of FHB pathogens and toxin types associated with wheat and barley in Brazil. We identified substantially higher FHB pathogen and toxin diversity than was previously documented in Brazil. We also documented substantial shifts in pathogen and toxin prevalence in growing seasons that were less conducive to FHB epidemics, indicating that rare toxin types may be more prevalent in grain when environmental conditions are less favorable to the dominant FHB pathogen. 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: We conducted a five-year survey (2011–2015) of barley and wheat fields in Paraná state, Brazil, analyzing 754 Fusarium isolates from Fusarium head blight (FHB)-symptomatic spikes. Multilocus genotyping and TEF-1a gene sequence analyses confirmed the dominance of the F. graminearum species complex (75.7%), but F. poae (11.5%) as well as F. avenaceum and related members of the F. tricinctum species complex (FTSC, 8.1%) appeared as substantial contributors to FHB. Within the FGSC, F. graminearum of the 15-ADON genotype was dominant (63%), followed by F. meridionale of the NIV genotype (23.1%), F. cortaderiae of the NIV (7%) or 3-ADON (2.6%) genotypes, and F. austroamericanum (3.8%) of the 3-ADON genotype. Substantial variation in pathogen composition was observed across years, with F. poae and F. meridionale frequencies significantly elevated in some years. Most F. poae strains produced DAS, diANIV and butenolide, but not Neosolaniol, T-2 or HT-2. All FTSC species produced moniliformin. Enniatin production was widespread among FTSC species, with the single F. acuminatum strain found to be the strongest producer of enniatins. Our findings confirm FGSC as a major contributor to FHB and expand considerably our knowledge of the presence, frequency and conditions under which other pathogens may emerge altering the spectrum of toxins that may accumulate in grain.