Drought Stress during Anthesis Alters Grain Protein Composition and Improves Bread Quality in Field-Grown Iranian and German Wheat Genotypes

Drought stress is playing an increasingly important role in crop production due to climate change. To investigate the effects of drought stress on protein quantity and quality of wheat, two Iranian (Alvand, Mihan) and four German (Impression, Discus, Rumor, Hybery) winter wheat genotypes, representing different quality classes and grain protein levels, were grown under field conditions in Eqlid (Iran) during the 2018–2019 growing season. Drought stress was initiated by interrupting field irrigation during the anthesis phase at two different stress levels. Drought stress at anthesis did not significantly change total grain protein concentration in any of the wheat genotypes. Similarly, concentrations of grain storage protein sub-fractions of albumin/globulin, gliadin and glutenin were unaltered in five of the six genotypes. However, analysis of protein sub-fractions by SDS polyacrylamide gel electrophoresis revealed a consistent significant increase in ω-gliadins with increasing drought stress. Higher levels of HMW glutenins and a reduction in LMW-C glutenins were observed exclusively under severe drought stress in German genotypes. The drought-induced compositional change correlated positively with the specific bread volume, and was mainly associated with an increase in ω-gliadins and with a slight increase in HMW glutenins. Despite the generally lower HMW glutenin concentrations of the Iranian genotypes and no effect of drought on the concentration of HMW sub-fraction, there was still high specific bread volume under drought. It is suggested that for the development of new wheat cultivars adapted to these challenging climatic conditions, the protein composition should be considered in addition to the yield and grain protein concentration.

High-molecular-weight (HMW) glutenin subunit composition of the Elite-II synthetic hexaploid wheat subset (Triticum turgidum × Aegilops tauschii; 2n = 6x = 42; AABBDD)

Characterization of high-molecular-weight (HMW) glutenins is an important criterion for identifying genotypes with good bread-making quality. In synthetic hexaploids (SHs), the D-genome encodes several allelic variants of HMW glutenins that require proper identification prior to their utilization for bread wheat (BW) improvement. In this study, SHs with promising agronomic features were characterized for HMW glutenin composition. Seven different allelic variants were observed at the Glu-Dt1 locus, three of which (1Dx1.5+1Dy10, 1Dx1.5+1Dy12.2 and 1Dx2.1+1Dy10) have not been previously reported in existing BW germplasm. The results also showed a variety of D-genome-encoded subunits along with superior glutenin alleles in the B-genome (1Bx7+1By8, 1Bx6+1By8 and 1Bx13+1By16). About 63% of these SHs encoded favourable allelic variants of HMW glutenins, which make them a good choice for improvement in wheat bread making. Glu-Dt1 encoded favourable allelic variants (1Dx5+1Dy10 and 1Dx1.5+1Dy10) that are frequently observed in SHs can be easily incorporated into BW through recombination breeding.

The effect of organic and conventional growing systems on quality and storage protein composition of winter wheat

Protein composition of the grain storage proteins (evaluation using electrophoresis in polyacrylamide gel – the SDS-PAGE method) and selected parameters of bread-making quality in a set of 6 winter wheat varieties from organic and conventional growing in Central Bohemia (elevation 295 m a.s.l.) were evaluated during a two-year experiment (2004 and 2005). In comparison with the varieties from organic growing, wheat varieties from the conventional growing were characterized by twice the percentage of High Molecular Weight (HMW) glutenins, responsible for dough elasticity (conventional wheat in average 25.22%, organic wheat 12.71%). At the same time, varieties from conventional growing generally reached higher, more positive values of crude protein content and wet gluten content in grain dry matter, sedimentation index by Zeleny and yield of bread. On the other hand, wheat varieties from organic growing were mainly characterized by significantly higher percentage of nutritionally valuable albumins and globulins (organic wheat in average 17.69%, conventional wheat 7.33%). In both systems of growing the highest percentage of HMW glutenins was determined in varieties from the quality group E (elite, the most suitable for bread-making), while the varieties from the quality group C (wheat unsuitable for bread-making) reached the highest percentage of residual albumins and globulins.