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Improved end‐use quality is an essential goal of many wheat (Triticum aestivumL.) breeding programs. Besides genetic factors, environmental conditions are known to influence wheat quality. Our objective was to identify quantitative trait loci (QTL) for quality traits in a winter wheat population under different soil moisture levels. A population of 185 doubled haploid (DH) lines was derived from a cross between hard white winter wheats CO940610 and ‘Platte’. The population was grown in four environments (two limited irrigation and two fully irrigated) in Colorado in 2007/2008 and 2008/2009, and the grain was evaluated for 14 end‐use quality traits. A linkage map was constructed with 250 molecular markers, including five glutenin protein markers. Composite interval mapping detected clusters of QTL for multiple traits near the glutenin loci Glu‐A1, Glu‐B1, and Glu‐D1. Other QTL clusters were located on chromosomes 2B, 6A, 7B, and 7D; the 2B and 7D QTL may reflect the presence of heading date QTL in the same regions. An epistatic interaction for mixograph traits was found between the chromosome 7B QTL and Glu‐B1, consistent with the presence of a regulatory gene on 7B. An apparently novel QTL for kernel weight and diameter was detected on chromosome 3B. Our results confirm similar genetic control of quality traits, especially for large‐effect QTL, for the levels of moisture stress in this study. These results may guide breeding programs in choosing parents and conducting marker‐assisted selection for improved end‐use quality.

Russian wheat aphid (RWA), Diuraphis noxia(Kurdjumov), is a significant insect pest of wheat (Triticum aestivumL.) and has had a major economic impact worldwide, especially on winter wheat in the western United States. Development of resistant cultivars remains the most viable method for RWA control, although the continuing emergence of new RWA biotypes virulent to deployed resistance genes reinforces the need for the discovery of new sources of resistance. Iranian wheat landrace accession PI 626580 has shown high levels of resistance to RWA biotypes 1 (RWA1) and 2 (RWA2), but the inheritance and chromosomal location of this resistance is unknown. The objectives of this study were to determine the inheritance of RWA2 resistance, identify closely linked markers, and map the chromosomal location of RWA2 resistance found in PI 626580. Bulked segregant analysis was conducted with a mapping population of 154 F2individuals derived from a single plant selection made from PI 626580 and ‘Yuma’ (a susceptible wheat cultivar). Phenotypic segregation of RWA2 resistance suggested a single dominant gene, provisionally designated Dn626580. Linkage mapping analysis identified three simple sequence repeat (SSR) markers, Xbarc214, Xgwm473, and Xgwm437, proximally linked to Dn626580near the centromere on the short arm of chromosome 7D at distances of 1.8, 5.0, and 8.2 cM, respectively. Dn626580, a new resistance gene found in PI 626580, could be used alone or by pyramiding with other resistance genes to develop cultivars with effective RWA resistance.

Russian wheat aphid (RWA) [Diuraphis noxia(Kurdjumov)] is an important pest of wheat (Triticum aestivumL.) in several production areas of the world. The most effective and economical approach for controlling RWA is to use resistant cultivars. A wheat line, ST‐ARS 02RWA2414‐11 (2414‐11), showed a high level of resistance to RWA biotype 2. Our objectives were to map the resistance gene and develop polymerase chain reaction (PCR)–based markers for marker‐assisted selection (MAS). A mapping population of 212 F2individuals was developed from a cross of 2414‐11 and the susceptible cultivar Yuma. The F2individuals and F2:3families were infested using biotype 2 RWA. The RWA resistance of 2414‐11 is controlled by a single major gene, provisionally designated as Dn2414Using standard PCR, 30 marker loci were found to be linked to Dn2414with recombination frequencies (θ) of 0.00 to 0.27 and logarithm of the odds to the base 10 (LOD) scores of 7.6 to 66.1. Of the 30 markers, 26 were tightly linked to Dn2414with θ ≤ 0.05. A genetic map was constructed consisting of 31 loci spanning a region of 34.7 cM. The close linkage of Dn2414with several rye chromosome 1R short arm (1RS)‐specific simple sequence repeat markers and low θ values around the Dn2414gene indicate that Dn2414is located on chromosome 1RS.1BL (translocation chromosome with IRS and wheat chromosome 1B long arm). Phenotypic and marker profiles of 2414‐11 and its relatives are the same as other lines known to carry Dn7The Dn2414gene is thus located on 1RS arm, and the large number of PCR markers will be valuable for MAS of this gene.

Fluorescence in situhybridization (FISH) is a useful technique for physical mapping of genes, markers, and other single‐ or low‐copy sequences. Since clones containing less than 10 kb of single‐copy DNA do not reliably produce detectable signals with current FISH techniques in plants, a bacterial artificial chromosome (BAC) partial library of barley was constructed and a FISH protocol for detecting unique sequences in barley BAC clones was developed. The library has a 95 kb average barley insert, representing about 20% of a barley genome. Two BAC clones containing hordein gene sequences were identified and partially characterized. FISH using these two BAC clones as probes showed specific hybridization signals near the end of the short arm of one pair of chromosomes. Restriction digests of these two BAC clones were compared with restriction patterns of genomic DNA; all fragments contained in the BAC clones corresponded to bands present in the genomic DNA, and the two BAC clones were not identical. The barley inserts contained in these two BAC clones were faithful copies of the genomic DNA. FISH with four BAC clones with inserts varying from 20 to 150 kb, showed distinct signals on paired chromatids. Physical mapping of single‐ or low‐copy sequences in BAC clones by FISH will help to correlate the genetic and physical maps. FISH with BAC clones also provide an additional approach for saturating regions of interest with markers and for constructing contigs spanning those regions.