Mapping Type I and Combining Type I and Type II Fusarium Head Blight Resistance in Wheat

Fusarium head blight (FHB), also commonly known as scab, is one of the most damaging wheat (Triticum aestivum L.) diseases in humid and semi-humid regions around the world. Single genes identified to-date in wheat for resistance to fusarium head blight (FHB) provide only partial resistance, and disease severity is highly influenced by environment. Multiple genes are required for effective resistance. Our hypothesis is that combining Type I (reduced initial infection) and Type II FHB resistance (inhibition of spread of the disease after infection) can provide more effective resistance. Identifying DNA markers for Type I resistance will be very valuable for selection. Our objectives are to 1) characterize a RIL population from the cross INW0412 (Type I resistance)/992060 (susceptible) for frequency of initial infection and map QTLs for Type I resistance and 2) combine Type I resistance from cultivars Goldfield, INW0412 and Truman; and Type II resistance of Fhb1 and Qfhs.pur-7EL backcrossed into adapted soft winter wheat lines and quantify augmentation of FHB resistance. A population of 198 F₆ RILs was characterized for FHB incidence at Lafayette, IN in 2011, and F₈ was characterized for Type I resistance in field tests in 2013 at Lafayette, Vincennes and Evansville, IN. A two-enzyme genotyping by sequencing (GBS) approach is in progress. The RIL Type I resistance field data and the GBS single nucleotide polymorphism (SNP) marker data will be used to construct a high-density genetic map to identify QTL contributing to Type I FHB resistance. BC F_1:2 lines have been genotyped for Fhb1 and Qfhs.pur-7EL markers. F_2:4 lines were characterized in replicated field tests at Lafayette in 2013 for Type I and Type II resistance. Lines with both Type I and II FHB resistance were identified based on phenotypic and SSR marker selection, and it was confirmed that lines with multiple markers associated with FHB resistance provide more FHB resistance than lines with few or no markers. Those lines will be beneficial for the improvement of FHB resistance in wheat.