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United States Department of Agriculture

Agricultural Research Service


Location: Bacterial Foodborne Pathogens & Mycology Research Unit

Title: Species and trichothecene genotypes of the Fusarium graminearum species complex causing head blight of wheat in Rio Grande do Sul State, 2011 season

item Nicollli, C -
item Spolti, P -
item Gomes, L -
item Ward, Todd
item Del Ponte, E -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 25, 2013
Publication Date: N/A

Technical Abstract: Fusarium head blight (FHB) is a disease of global concern to wheat especially where legislation sets maximum limits for Fusarium mycotoxins, including Brazil. The disease is caused by members of the Fusarium graminearum species complex (FGSC) which are commonly classified into three trichothecene chemotypes: 3-acetyl(A) deoxynivalenol(DON), 15-ADON and nivalenol (NIV). In 2011, 60 fields were visited, two to three weeks after flowering, and 200 wheat spikes were randomly sampled in each field. In the laboratory, FHB incidence and severity were determined visually. Diseased kernels were placed in a humidity chamber and isolations were made from typical FGSC colonies. DNA was extracted from fresh mycelia of purified colonies growing on potato dextrose agar (PDA) media for seven days. Phylogenetic species and trichothecene genotypes were determined via a multilocus genotyping (MLGT) assay. The disease was found in all fields; mean FHB incidence and severity were 15,3% (1 to 59%) and 0,87% (0,03 to 5,04%), respectively. For 95 isolates obtained from 37 fields (2,49 isolates/field), four species were found: F. graminearum (88%), F. meridionale (7%), F. cortaderiae (3%) and F. asiaticum (2%). All species except F. graminearum (with a 15-ADON genotype) were of the NIV genotype. We confirm the dominance of F. graminearum among FHB isolates from wheat in Brazil, but demonstrate that at least three species with the NIV genotype comprise about 12% of these isolates in a non-epidemic year.

Last Modified: 4/19/2014
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