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Abstract
Genetic resistance is a more environmentally friendly, cost-effective solution to manage damage caused by Hessian fly (HF) (Mayetiola destructor Say), leaf rust (LR), caused by Puccinia triticina Eriks (Pt), or stripe rust (YR), caused by Puccinia striiformis (Pst), in soft red winter wheat (SRWW). The objectives of these studies were to evaluate germplasm for HF, LR, and YR resistance, map genomic loci expressing resistance, and validate KASP markers for marker-assisted selection (MAS). For the first study, we evaluated at seedling and adult plant stages a recombinant inbred line (RIL) population produced from a cross between HF resistant UGA 111729 and HF susceptible AGS 2038. We were able to detect a significant stable quantitative trait locus (QTL) on the long arm of chromosome 3D. IWB65911, a single nucleotide polymorphism (SNP) marker cosegregating with H32, was associated with our QTL peak. KASP marker validation with IWB65911 revealed that UGA 111729 expressed H32, and the marker was able to differentiate resistant or susceptible RILs for HF. For the second study, two RIL populations, one with 202 lines produced from a cross between resistant GA06493-13LE6 and susceptible Hilliard (UX1992) and one with 186 lines produced from a cross between GA06493-13LE6 and susceptible MPV57 (UX2029), were evaluated in Plains and Williamson, Georgia (GA) for HF resistance. Six major QTL were observed. UX1992 expressed
QHf.ux1992.1A.1 on chromosome 1A and QHf.ux1992.6A.1 on chromosome 6A, and UX2029 expressed QHf.ux2029.6A on chromosome 6A. The resistant allele for both 6A QTL came from GA06493-13LE6, and the resistant allele for QHf.ux1992.1A.1 came from Hilliard. HF resistance gene H7 KASP markers underlaid the 6A QTL, and a HF resistance gene h4 KASP marker underlaid QHf.ux1992.1A.1. For the last study, a diversity panel of 266 SRWW genotypes was evaluated in the field at the adult plant stage and the greenhouse at the seedling stage for LR and YR resistance. Using genome-wide association study (GWAS), 26 presumed novel QTL were detected, including ten major QTL. QTL QLrYr-2A.1 was detected on chromosome 2A and expressed the highest phenotypic variance (30.76%). All detected QTL did not overlap with any known LR or YR resistance genes.