Fusarium head blight (FHB), caused mainly by the fungus Fusarium graminearum, is an important wheat disease in several producing areas worldwide, including in Southern Brazil. The pathogen causes yield losses and also qualitative losses, once the infected grains get contaminated with mycotoxins, especially the Deoxynivalenol.

The use of molecular markers is a proven strategy to increase the efficiency in breeding programs. The aim of this study is mapping through GWAS, new QTL responsible for FHB resistance in a panel of Brazilian varieties evaluated at Southern Brazil. The panel was composed by 252 genotypes. The lines were genotyped with the technologies Silico DArT and DArTSeq. After a filtering procedure, a total 5154 markers remained for the analysis. The panel was assayed in two field seasons, 2021 and 2023, at the municipality of Coxilha, Rio Grande do Sul, Brazil.

Three traits were evaluated: i) FHB general score; ii) Fusarium Damaged Kernels (FDK); iii) Deoxynivalenol (DON) contend (only in 2023), totalizing 7 variables, as single and combined (average) analyses were performed. The Mixed Linear Model (MLM) implemented in Tassel V.5 was applied. Principal Components Analysis (PCA) (6 components) and the Kinship Matrix by Centered IBS method were used to correct population structure. Only FDK and DON in 2023 presented significant SNPs. For FDK, the significant SNPs were in the chromosomes 4A and 7A.

On the other hand, for DON, the significant SNPs were found in chromosomes 3A, 3D, 4A, 4D and 5A. The SNP with largest effect is the one in chromosome 4A, for FDK, which reduces 19% of damaged kernels in resistant genotypes. The same SNP has shown effect for DON reduction.

The SNPs will be converted to routine markers. As a conclusion, the panel presented important genetic variability, which allowed mapping QTLs for Fusarium head blight resistance.