Genotypic and Environmental Modification of Wheat Flour Protein Composition in Relation to End‐Use Quality

Abstract

Identification of the biochemical factors responsible for end‐use quality variation of wheat (Triticum aestivum L.) would have important consequences for breeders, producers, grain handlers, millers, and bakers. Flour protein composition, or the distribution of flour protein in classes based on molecular size and solubility, has been reported to be a major variable influencing wheat processing quality. The proportions of five major protein fractions in flour samples of 30 wheat genotypes, obtained from 17 Nebraska environments, were measured by size‐exclusion high‐performance liquid chromatography (SE‐HPLC). Total flour protein content and sodium dodecylsulfate (SDS) sedimentation volume (SDSS), the latter a measure of flour protein aggregative ability, also were measured. The extent to which each character was modified by genotypic, environmental, and genotype × environment interaction sources of variation was determined. Phenotypic correlations were used to relate biochemical variation to wheat end‐use quality characteristics. Flour protein concentration and SDSS were more consistently correlated with quality variables than any of the protein fractions measured by SE‐HPLC. Interdependence of flour protein concentration and SE‐HPLC protein fractions prevented the identification of specific effects of the latter on wheat processing quality. The proportion of glutenin, however, was found to be significantly related to loaf grain properties, a parameter of critical concern to the milling and baking industry. Genotypes with both elevated and depressed proportions of glutenin, independent of flour protein concentration, were identified.