Variation of high-molecular-weight glutenin subunits and glutenin macropolymer particle distribution in wheat grains produced under different water regimes

Genome-wide association study of agronomic and quality traits in a world collection of the wild wheat relative Triticum urartu

Triticum urartu (2n = 2x = 14, subgenome A^u A^u ), a wild diploid wheat progenitor, features broad allelic diversity for a number of traits of agronomic relevance. A thorough characterization of the diversity of T. urartu natural accessions may provide wheat breeders with new alleles potentially contributing to wheat improvement. In this study, we performed an extensive genotypic and phenotypic characterization of a world collection of 299 T. urartu ex situ accessions, developing 441 327 single nucleotide polymorphisms and recording trait values for agronomic and quality traits. The collection was highly diverse, with broad variation in phenology and plant architecture traits. Seed features were also varied, and analyses of flour quality reported 18 distinct patterns of glutenins, and carotenoid concentrations and sedimentation volumes in some cases surpassing those of cultivated materials. The genome-wide molecular markers developed on the collection were used to conduct a genome-wide association study reporting 25 highly significant quantitative trait nucleotides for the traits under examination, only partially overlapping loci already reported in wheat. Our data show that T. urartu may be considered a valuable allele pool to support the improvement of wheat agronomy and quality.

Effect of enzymatic crosslinking on the handling properties of dough as a function of NaCl levels for CWRS varieties, Pembina and Harvest

The effects of transglutaminase (TG) and glucose oxidase (GO) on the handling properties of model bread dough were examined at both normal (2% wt. by flour) and reduced (1% wt.) sodium chloride (NaCl) levels using two Canada Western Red Spring (CWRS) cultivars; Pembina and Harvest. The reduction of NaCl level had negative effects on dough rheology and stickiness, however, the inclusion of GO (0.001 and 0.01% by flour weight) or TG (only at the 0.5% by flour weight inclusion) was able to improve dough strength and reduce stickiness. GO appeared to be more effective than TG (at 0.01%) at equivalent concentrations for improving dough-handling properties. Flour cultivar had significant effects; Harvest flour (weaker) was more impacted by salt reduction and enzyme inclusion compared to Pembina flour (stronger). Crosslinking assays showed significant differences in glutenin macropolymer (GMP) content in dough prepared with GO, and dough prepared with different flours. Additionally, significantly fewer free thiol groups were found in dough produced with GO compared to dough without any enzymes and those with TG. GO appears to have potential for use as a bread improver to reduce stickiness and improve the strength of bread dough produced at lower salt concentrations, especially for dough prepared with weaker flour cultivars.

Aggregation characteristics of protein during wheat flour maturation

BACKGROUND

The protein aggregation characteristics of three types of freshly milled wheat flour with high, medium or low gluten were investigated during 90 days of maturation. Changes in the content and particle size of the glutenin macropolymer (GMP), contents of sulfhydryl groups and disulfide bonds (SS), and secondary structure and molecular weight distribution of the protein were determined.

RESULTS

For high, medium and low gluten flour, GMP content increased to 22.25, 13.72 and 10.32 g kg^-1 ; free sulfhydryl group content decreased by 5.5%, 4.1% and 4.4%; and SS content increased by 1.6%, 1.8% and 2%, respectively. The proportion of β-sheet and random coil increased, and the proportion of α-helix and β-turns decreased. The polymeric protein content increased, whereas that of gliadin decreased.

CONCLUSION

Protein aggregation mediated by SS cross-linking helped develop a stronger gluten network. The findings provide theoretical support for the changes in protein structure during flour maturation and also help to predict the quality of wheat flour and its products. © 2018 Society of Chemical Industry.