| Wheat (Triticum aestivum L.) is a staple global crop, resulting in significant efforts to create sustainable cropping systems through improving agronomic traits and enhancing disease and insect pest resistance in commercial cultivars. Our first objective was to develop a genetic linkage map using 188 recombinant inbred lines from a 'Louise' by 'Penawawa' cross to identify quantitative trait loci (QTL) for high-temperature, adult-plant resistance to stripe rust (Puccinia striiformis f. sp. tritici). The genetic linkage map was constructed using 295 polymorphic simple sequence repeat and one single nucleotide polymorphism markers. F5:6 lines were evaluated for stripe rust reaction, and subsequent agronomic traits, under natural infection in replicated field trials at five locations in the U.S. Pacific Northwest in 2007 and 2008. One major QTL, designated QYrlo.wpg-2BS, associated with HTAP resistance in Louise, was detected on chromosome 2BS (LOD scores ranging from 5.5 to 62.3 across locations and years) and flanked by Xwmc474 and Xgwm148. Our second objective was to identify DNA markers associated with the Hessian fly (Mayetiola destructor [Say]) resistance gene H3. Fifteen plants per line were evaluated under greenhouse conditions, scored as either resistant or susceptible and data were converted to percentage of plants susceptible. Two markers, Xpsp2999 and Xcfd15 were significantly associated with H3 at a LOD score of 65.2, and accounted for 83% of the phenotypic variation. Our third objective was to identify QTL associated with seedling growth habit, leaf color, plant height, heading date, maturity date, grain volume weight, grain protein concentration, and grain volume. The QTL QFlt.wak-2D and QMat.wak-2D were associated with the Ppd-D1 gene for photoperiod insensitivity. Variation in plant height was associated with three QTL on chromosome 3B and one QTL on chromosome 2D. A QTL for leaf color was identified on chromosome 2B. Grain yield QTL were attributed to the effects other QTL had on pest resistance, plant growth and adaptability. Seedling growth habit mapped to chromosome 2D, and a significant QTL for grain volume weight was detected on chromosome 1D. Forward breeding strategies implementing selection using these markers will increase agronomic performance and the durability of pest resistance in developed cultivars. |
