Effect of allelic variation at glutenin and puroindoline loci on bread-making quality: favorable combinations occur in less toxic varieties of wheat for celiac patients

Genetically diverse wheat samples, twenty-seven Triticum aestivum L. varieties, grown in two environments (Portugal and Spain) were analyzed for their allelic composition in high-molecular-weight glutenin subunits (HMW-GS), low-molecular-weight glutenin subunits (LMW-GS) and puroindolines, as well as their protein content, hardness, sodium dodecyl sulfate-sedimentation (SDS-S), mixograph mixing time and breakdown resistance (MT and BDR, respectively) parameters, and R5 reactivity. The environment showed significant effect on protein content, SDS-S and BDR parameters. In relation to HMW-GS quality effect, the allelic composition Glu-A1d, Glu-B1al, Glu-D1d presented the best results. From the complex Glu-3 loci (LMW-GS), only Glu-B3 locus showed a significant effect on the quality parameters. The Glu-B3ab allele is desirable considering the higher mean values for SDS-S, MT and hardness, and the lower mean values for BDR. Regarding puroindolines, Pina-D1a, Pinb-D1c allelic composition (Leu to Pro at position +60) showed the best quality potential. In addition, we found negative (SDS-S and MT) and positive (BDR) significant correlations between quality parameters and the amount of potential celiac disease toxic epitopes, suggesting that wheat breeding aiming at quality does not have a negative impact on wheat toxicity and on the other hand, emphasizes the need for a more comprehensive wheat breeding programs that encompass celiac disease problematic.