GWAS of Morphological and Scab Resistance Traits in the Elite Eastern Wheat Mapping Panel.

Fusarium head blight (FHB) is a destructive disease of wheat and other small grains. This disease is caused by Fusarium graminearum, a pathogen that reduces yield and grain quality of winter wheat (Triticum aestivum L.). Furthermore, this pathogen produces a harmful toxin known as deoxynivalenol (DON). Resistance genes have been identified; however, because of incomplete resistance, the search for resistance must encompass other factors such as morphological characteristics. The objectives of this study were to evaluate morphological and disease traits in the TCAP elite eastern mapping panel and to conduct a genome wide association study with the phenotypic and genotypic data. Two hundred sixty two wheat cultivars and breeding lines from the mapping panel were used in two experiments each conducted over two years (2015-2016) at Lexington, KY. In the first study, anther extrusion, plant height, spike length, spike density, number of florets, peduncle length and spike inclination were measured. Evaluation of disease traits was carried out in an inoculated, irrigated nursery; heading date, plant height, disease incidence and severity, FHB rating, FHB index, Fusarium damaged kernels (FDK) and DON were measured. Genotype x year interaction was significant (P<0.05) for all traits measured in this study. The association study showed for anther extrusion possible QTL located on chromosomes 1B and 5B. Heritability for that trait was 0.23. For spike inclination, potential QTL were located on chromosomes 5B, 6B, and 7D. Implications for breeding programs will be discussed.