Five-year Survey Uncovers Extensive Diversity and Temporal Fluctuations Among Fusarium Head Blight Pathogens of Wheat and Barley in Brazil

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-1α 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.

Phenotypic and molecular characterization of the resistance to azoxystrobin and pyraclostrobin inFusarium graminearumpopulations from Brazil

“…All strains, except strains from PR (2018, 2019 and 2020), were identified in previous studies using sequencing or multilocus genotyping (MLGT;Del Ponte et al, 2015;Pereira et al, 2021). The unidentified strains from PR state were assayed using the Fg16-F/R primers, which allow differentiation between F. graminearum (<500 bp) and Fusarium meridionale (>500 bp) according to the band product size (Hafez et al, 2020;Nicholson et al, 1998).…”