Genetic Mapping of Quantitative Trait Loci Associated with Important Agronomic Traits in the Spring Wheat (Triticum aestivum L.) Cross 'Louise' x 'Penawawa'

Understanding the genetic factors underlying agronomic traits in common wheat (Triticum aestivum L.) is essential to making gains from selection during the breeding process. A set of 188 recombinant inbred lines (RILs) from a 'Louise' x 'Penawawa' mapping population was grown for two crop years at two locations in the Pacific Northwest region of the United States to identify quantitative trait loci (QTL) associated with seedling growth habit, leaf color, plant height, flowering date, maturity date, grain volume weight, grain protein content, and grain yield. Quantitative trait loci for flowering date and maturity date were associated with the Ppd-D1 gene for photoperiod insensitivity. Variation in the QTL for plant height was dependent on location and year and localized to chromosome 2D and 3B. A QTL for leaf color was identified on chromosome 2B. Seedling growth habit mapped to chromosome 2D, and a significant QTL for grain volume weight was detected on chromosome 1B. Quantitative trait loci were identified for grain yield; however, some of these QTL were associated with other known QTL for pest resistance, seedling growth habit, or photoperiod insensitivity. Flowering date, maturity date, and plant height were significantly correlated, which resulted from the pleiotropic effects of the Ppd-D1 gene. The identification of agronomic QTL, and the correlations between and among them, is the first step toward making gains from selection using molecular marker-assisted selection for these important agronomic traits.