Evaluation of Some Molecular Resistance Markers of the Wheat Cultivars for Control of Head Blight Disease Caused by Fusarium graminearum in Salah Aldin Province, Iraq

Abstract

Twelve fungal isolates of the genus Fusarium were isolated from bread wheat grains infected with Fusarium head blight; 4 isolates of F. culmorum, 3 isolates of F. graminearium, 2 isolates of F. equiseti and F. moniliforme, and one isolate of F. avenaceum. The results obtained showed that all of these isolates caused head blight disease in wheat (Tamoz 2 cultivar). The isolates F. graminearium 2, F. graminearium 3 and F. culmorum 3 showed the highest Fusarium infection index (FII), which was 51.45, 50.37, and 50.03, respectively, whereas the lowest values were 24.61 and 32.04 for the isolates of F. culmorum and F.avenaceum, respectively. The identification of the most pathogenic isolates of F. graminearium 2 was confirmed by molecular diagnosis based on the matching of the nucleotide sequence of the 5.8S rRNA gene of this fungus with the nucleotide sequences of the fungal strains contained in the World Genbank database (listed on the NCBI website) and this isolate was recorded in Global Genbank under the accession number MT998864.1. The results obtained also showed that 12 of the studied wheat cultivars (Sham 6, Abu Ghraib, Babil, Milan, Sally, Hadbaa, Rabia, Bohoth 206, Sham 4, Iba 99, Dor 29 and Al Ezz) had the lowest infection levels compared to other cultivars. The FII values obtained suggested a significant superiority of the cultivars Sham 6, Abu Ghraib, Milan and Babel (which did not differ significantly among each other) with lowest values of 16.84, 16.86, 17.44 and 17.84, respectively. The effect of infection with FHB was reflected in the percentage of Fusarium damaged kernels (FDK), with lowest values of 38.43, 39.23, 41.58, 41.82 and 42.03% for the cultivars Sham 6, Abu Ghraib, Milan, Babel and Hadba, respectively. The electrophoresis of PCR products of Xgwm389, 6B NOR and Xgwm 126 markers associated with the resistance genes Fhb1, Fhb2 and Fhb3, respectively, carried out on twenty eight wheat cultivars showed that four cultivars (Sham 6, Abu Ghraib, Babel and Milan) produced bands of 140 bp in size for the marker of Fhb1 gene (Xgwm389), which is considered one of the indicators for resistance to FHB disease of wheat. The test also showed the presence of a single band of 220 bp in the wheat cultivar Sally for the gene marker Fbh2 (6B NOR), which indicates resistance to FHB disease. Whereas, the electrophoresis product for the gene marker Fhb2 (Xgwm 126) produced a band of 2100 bp in size, reflecting the presence of resistance characteristic in this cultivar. The results of this study indicated the presence of a relationship between the decrease in the infection parameters with the presence resistance genetic markers in the cultivars Sham 6, Abu Ghraib, Babel, Milan, Sally and Hadbaa, whereas the cultivars Rabia, Bohoth 206, Sham 4, Iba 99, Dor 29 and Al Ezz showed a decrease in infection parameters to a lesser degree than the remaining cultivars, but without the presence of the genetic markers investigated. Keywords: Fusarium head blight disease, molecular markers, resistance genes, wheat cultivars, Fusarium sp