RELATIONSHIPS BETWEEN PROTEIN-COMPOSITION AND MIXOGRAPH AND LOAF CHARACTERISTICS IN WHEAT

To study the relationships between protein composition and baking properties of 135 randomly selected wheat (Triticum aestivum) lines from a randomly mated population, we analyzed gliadin proteins by acidic buffer polyacrylamide gel electrophoresis (PAGE) and high molecular weight (HMW) glutenin proteins by PAGE in the presence of sodium dodecyl sulfate. The amount of protein in each gliadin band was estimated from densitometer scans, and presence or absence of particular glutenin subunits was recorded. Simple correlations were calculated among individual gliadin bands, Payne glutenin score, and each of five quality parameters: mixing time, mixing tolerance, water absorption, loaf volume, and crumb grain score. Five gliadin bands were correlated with loaf volume, two with crumb grain score, 12 each with mixing time and mixing tolerance, and six with water absorption. No correlations were detected between protein concentration and presence of any particular gliadin or glutenin proteins. Payne score was significantly correlated only with loaf volume and mixing time. Significant correlations were found between protein concentration and both loaf volume and absorption and between mixing tolerance and crumb grain score. No associations were found between total protein content and mixing properties. Multiple regression analyses were conducted for each of the functional tests, with the individual gliadin and/or HMW glutenin bands as independent variables. Prediction of 26-45% of the variation in quality parameters required eight to 11 gliadin and glutenin bands. Glutenin subunits 5 + 10 had the most consistently positive effect on most of the quality measurements. These biochemical methods can be used to identify wheat genotypes with specific HMW glutenin and gliadin composition in parental and early-generation selections, but phenotypic quality traits must be considered as well.