Authors: Lawrence Tidakbi 1, Guihua Bai 2, Jessica L. Rupp Noller 1, and Katherine W. Jordan 2
1. Department of Plant Pathology, Kansas State University, Manhattan, KS
2. Department of Agronomy, Kansas State University, Manhattan, KS
2. United States Department of Agriculture-Agriculture Research Services (USDA-ARS) Hard Winter Wheat Genetics Research Unit (HWWGRU), Manhattan, KS
Corresponding Author: Katherine Jordan, katherine.jordan@usda.gov
Presenting Author: Lawrence Tidakbi
Abstract
Advancing Fusarium head blight (FHB) resistance relies on discovering new sources of genetic resistance through novel genomic loci linked to causal genes. Current adapted wheat cultivars exhibit only moderate genetic resistance, which has proven insufficient due to the quantitative nature of disease resistance. We developed a diverse panel of 269 winter wheat lines representing different U.S. wheat-growing regions to uncover novel loci and enhance breeding efforts. We employed exome and promoter capture sequencing to generate single nucleotide polymorphisms (SNPs) for the panel, focusing on gene coding and regulatory regions, which are typically informative based on other traits and disease interactions. Three years (2022, 2023, 2024) of field evaluations were conducted to assess each line's response to FHB, focusing on disease severity metrics, including Area Under the Disease Progress Curve (AUDPC), Fusarium Damaged Kernel (FDK), and Deoxynivalenol (DON) content. Using these phenotypic data, we performed genome-wide association studies (GWAS) to identify genomic loci associated with FHB resistance. The results show significant variability in disease severity metrics (p-value <0.05) across breeding lines, including some more resistant than the moderately resistant checks. Exome and promoter capture generated ~645,000 overlapping SNPs. Using the best linear unbiased estimates (BLUEs) values of the FHB disease severity metrics, we mapped novel QTLs conferring FHB resistance or susceptibility alleles using mixed linear models (MLM) in GWAS. Some significant novel QTLs were identified to be associated with FHB disease severity metrics with heritability of traits being 0.58 for AUDPC, 0.57 for FDK, and 0.32 for DON. These newly identified QTLs will undergo validation through Kompetitive Allele Specific PCR (KASP) assays on independent populations. Incorporating these rare loci into adapted wheat varieties has the potential to strengthen genetic resistance to FHB in winter wheat, providing farmers with more robust options to mitigate the disease.