Genetic Improvement for End-Use Quality in Wheat

Abstract

End-use quality of wheat is greatly dependent on flour protein content and composition. Milling and end-use quality of wheat results from the composition of the kernel, especially the endosperm. A unique feature of wheat flour is that when it is mixed with water it forms dough, a material with complex rheological properties. Gluten, an essential component of dough, is a complex protein network formed mainly by two kinds of proteins, monomeric gliadins and polymeric glutenins, which in turn are divided into high molecular weight glutenins (HMWGs) and low molecular weight glutenins (LMWGs). The visco-elastic properties and gas holding capacity of wheat flour dough are the basis for the production of a wide range of products. Variation in the composition results from the interaction between the ‘genotype’ and the ‘environment’. Wheat cultivars must have suitable end-use quality for release and consumer acceptability. However, breeding for quality traits is often considered a secondary target compared to yield mainly because of quantity of seed needed and cost involved in breeding for quality traits. Acceptable end-use quality, rather than enhanced end-use quality is the goal in most of the wheat breeding programs because currently there are inadequate economic incentives to develop wheat cultivars only with enhanced end-use quality. Grain end-use quality traits, such as milling yield, dough rheology, baking, and noodle traits are among the most important in wheat breeding. However, these traits are difficult to breed for as their assays require grain and flour quantities that can only be obtained in advanced generations in the breeding cycle, and are expensive. Without testing and selection, many undesirable materials are advanced, expending additional resources. Breeders use grain or flour protein (FP%), sedimentation (SDS), and high molecular weight (HMW) glutenin subunit data to truncate their breeding populations early in the breeding process. Heritability in various traits of grain end-use quality traits in wheat varies widely. Breeders must continue to develop and release new wheat cultivars with acceptable end-use quality.