Plant & Animal Genomes XV Conference

January 13-17, 2007
Town & Country Convention Center
San Diego, CA

Identifying QTLs For The ‘Extra-Soft’ Characteristic In Wheat

Guomei Wang , Jeffrey M. Leonard , Andrew S. Ross , Jim Peterson , Oscar Riera-Lizarazu

  Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331

Soft white winter (SWW) wheat dominates the ~1,000,000 acres of cultivated wheat in Oregon (USA) with an estimated value over $200 million. The ‘extra-soft’ grain characteristic, which positively affects flour yield and end-use quality, has resulted in the development of a novel class of soft white wheat (SWW) cultivars with the potential to widen our export markets. As one of 17 nation-wide labs contributing to the Wheat Coordinated Agricultural Project (CAP), our goal is to genetically dissect the value-added ‘extra-soft’ kernel trait and to identify markers for indirect selection and cultivar development. A genetic map is being been constructed based on simple sequence repeats (SSR). The mapping population consists of 168 recombinant inbred lines (RILs) derived from a cross between SWW cultivar ‘Stephens’ (hardness index = 43.5) and ‘OR9900553’ (hardness index = 21.0), an advanced breeding line with the ‘extra-soft’ grain characteristic. In a preliminary analysis, the hardness index of a subset of ~40 lines were obtained using the single kernel characterization system (SKCS). Grain hardness measurements and a partial genetic map (~120 markers) were used for composite interval mapping. Two QTLs affecting kernel hardness, one each on chromosomes 2A and 3D, were detected. The QTL on chromosome 2A and chromosome 3D accounted for 34% and 15% of the phenotypic variance, respectively. A more thorough assessment with a larger phenotypic data set and a denser map is ongoing. The biological basis for the ‘extra soft’ characteristic is also under investigation.