Physiological mechanisms in near isogenic spring wheat sister lines contributing to differences in grain yield and grain protein.

Wheat (Triticum aestivum L.) is the most widely grown cereal crop in Canada covering more than 10 million hectares. Canadian wheat has been well recognized by the industry and consumers all over the world for its quality. Wheat breeders aim to improve grain yield and grain protein concentration for better milling, gluten strength and other rheological characteristics. Grain yield and grain protein concentration are negatively correlated, influenced by a complex genetic relationship among the traits, which makes improving both very difficult. Five isogenic sister lines were developed at the Swift Current Research and Development Centre, Swift Current, SK, Canada from an elite spring wheat breeding population named ‘B1018’ (BW928/BW431//Carberry). These sister lines differ for grain yield, grain protein, and test weight although maturity and plant height, were indistinguishable in field trials. To better understand the mechanisms regulating the yield and protein relationship in these wheat sister lines, in-depth field and greenhouse experiments were conducted. Here we report preliminary findings with studies on spike morphological traits, yield fill rate, and N uptake, partitioning and post-anthesis remobilization to decipher physiologically mechanisms in wheat sister lines carrying differential traits associated with grain yield and protein quality. Outcomes from the studies using various physiological, biochemical and molecular approaches are discussed.