Use of near-isogenic wheat lines to determine glutenin and gliadin composition and funtionality in flour tortillas
The synthesis of high molecular weight (HMW) glutenin, low molecular weight glutenin and gliadin proteins are controlled by nine major loci present in wheat chromosomes. The loci Glu A1, Glu B1, Glu D1 and Gli A1, Gli B1, Gli D1 and Gli 2 and their allelic variants play important roles in determining the functional properties of wheat flour. This study focused on understanding the functionality of these protein subunits with respect to tortilla quality for use in developing varieties with ideal tortilla baking quality. Near-isogenic wheat lines in which one or more of these loci were absent or deleted were used in the study. These lines were analyzed using SSR primers to verify the chromosome deletions. A standard SDS PAGE gel and a Lab on Chip Capillary Electrophoresis method were used to confirm the protein composition of the deletion lines. Tortillas were prepared from each deletion line and the parent lines used to derive the deletion lines, and tortilla quality evaluations were analyzed. The analysis has revealed that elimination of certain HMW glutenins results in gain of function both for tortilla diameters and overall tortilla quality. The deletion line possessing 17+18 at Glu B1 and deletions in Glu A1 and Glu D1 had a gain of function in tortilla diameter, yet tortilla stability was compromised. The deletion line possessing Glu A1, Glu D1 (1,5+10) and a deletion in Glu B1 improved both the diameters and stability of the tortillas. Presence of subunits 5+10 is important for maintaining tortilla stability. Deletions in gliadin monomeric proteins also affected the tortilla diameters and stability.