Barley Stripe Rust Resistance QTL: Development and Validation of SNP Markers for Resistance to Puccinia striiformis f. sp. hordei.

Quantitative trait loci (QTL) for barley stripe rust resistance were mapped in recombinant inbred lines (RIL) from a 'Lenetah' × 'Grannelose Zweizeilige' (GZ) cross. GZ is known for a major seedling resistance QTL on chromosome 4H but linked markers suitable for marker-assisted selection have not been developed. This study identified the 4H QTL (log of the likelihood [LOD] = 15.94 at 97.19 centimorgans [cM]), and additional QTL on chromosomes 4H and 6H (LOD = 5.39 at 72.7 cM and 4.24 at 34.46 cM, respectively). A QTL on chromosome 7H (LOD = 2.04 at 81.07 cM) was suggested. All resistance alleles were derived from GZ. Evaluations of adult plant response in Corvallis, OR in 2013 and 2015 provided evidence of QTL at the same positions. However, the minor QTL on 4H was not statistically significant in either location/year, while the 7H QTL was significant in both. The single-nucleotide polymorphism markers flanking the resistance QTL were validated in RIL from a '95SR316A' × GZ cross for their ability to predict seedling resistance. In 95SR316A × GZ, 91 to 92% of RIL with GZ alleles at the major 4H QTL and at least one other were resistant to moderate in reaction. In these populations, at least two QTL were required to transfer the barley stripe rust resistance from GZ.

Detection of QTL linked to Fusarium head blight resistance in Sumai 3-derived North Dakota bread wheat lines.

During the past decade Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe has resulted in severe grain yield and quality losses of wheat (Triticum aestivum L.) in the Northern Great Plains of the U.S. Given the complexity of breeding for FHB resistance, molecular markers associated with this trait will be valuable in accelerating efforts to breed resistant cultivars. The objective of this study was to identify molecular markers linked to quantitative trait loci (QTL) for FHB resistance in wheat using a set of lines obtained by several cycles of crossing to North Dakota adapted genotypes, which derived their resistance from cv. Sumai 3. Microsatellite markers spanning the wheat genome were used to screen parents and derived lines. Polymorphisms for parental alleles were compared to disease scores for Type II resistance. The probability of linkage between markers and introgressed resistance genes was calculated using a binomial probability formula based on the assumption that a molecular marker at a specific distance from the introgressed gene, in a near-isogenic line (NIL), will carry the donor-parent allele as a function of the distance between marker and gene and the number of backcrosses/selfs performed in deriving the NIL. Microsatellite loci Xgwm533 and Xgwm274 were significantly associated with QTL for FHB resistance.