Search

Drought is increasingly becoming a production constraint in wheat world-wide. Arbuscular mycorrhizal fungi (AMF)-bread wheat symbiosis has been shown to improve the tolerance under drought stress. The objective of this study was to determine the effects of AMF inoculation on yield attributes (spike number per plant, spike weight per plant, number of grains per spike, grain weight per spike and 1000 grain weight) and protein quantity and quality in two bread wheat cultivars (PAN3497 and SST806) grown under drought stress. Plant growth was significantly reduced due to drought stress in both cultivars. Shoot dry weight was significantly increased (23%) due to AMF inoculation in SST806. AMF inoculation caused a further significant increase of protein content in both cultivars (10.70% and 13.42% in PAN3497 and SST806, respectively). Low molecular weight (LMW) glutenin was significantly decreased in PAN3497 under drought stress. However, the monomeric proteins were significantly increased by drought and/or a combination of drought and AMF inoculation in both cultivars. In cultivar SST806, significant reduction of polymeric protein was observed due to application of both AMF (6%) and a combination of AMF with drought stress (4%). Regarding the two-dimensional separation of the gluten proteins, drought had the largest effect on protein spots, with AMF causing up-regulation of only some spots. SST806 was generally more drought tolerant than PAN3497. [ABSTRACT FROM AUTHOR]

Four hard red bread wheat cultivars with the same high molecular weight glutenin subunit (HMW-GS) composition (1Ax1, 1Bx13, 1By16, 1Dx5 and 1Dy10), developed for each of two production regions (irrigation and dryland) in South Africa, were tested at two representative locations of each region for two consecutive seasons to determine how different genetic backgrounds, locations and seasons influenced the quantity of the HMW-GS expressed, and how this affected baking quality characteristics. Location contributed the most to the observed variation in the bread making quality characteristics. In the irrigation region, subunit 1Ax1 was correlated significantly to most quality traits, especially flour protein and wet gluten content. In the dryland region, significant positive correlations for similar characteristics were expressed by subunit 1Dx5, showing that the influence of these subunits were not constant across the localities. This also highlighted the importance of the x-type subunits in the bread wheat quality breeding programs of South Africa. [ABSTRACT FROM AUTHOR]

Drought and temperature stress can cause considerable gluten protein accumulation changes during grain-filling, resulting in variations in wheat quality. The contribution of functional polymeric components of flour to its overall functionality and quality can be measured using solvent retention capacity (SRC). The aim of this study was to determine the effect of moderate and severe drought and heat stress on SRC and swelling index of glutenin (SIG) in six durum wheat cultivars with the same glutenin subunit composition and its relation with gluten protein fractions from size exclusion high performance liquid chromatography. Distilled water, sodium carbonate and sucrose SRC reacted similarly to stress conditions, with moderate heat causing the lowest values. Lactic acid SRC and SIG reacted similarly, where severe heat stress highly significantly increased the values. SIG was significantly correlated with sodium dodecyl sulphate sedimentation (SDSS) and flour protein content (FPC) under all conditions. Lactic acid SRC was highly correlated with FPC under optimal and moderate heat stress and with SDSS under moderate drought and severe heat. SIG was negatively correlated with low molecular weight glutenins under optimal and drought conditions, and combined for all treatments. The relationship between SRC and gluten proteins was inconsistent under different stress conditions. [ABSTRACT FROM AUTHOR]

Drought stress is becoming more prevalent with global warming, and has been shown to have large effects on gluten proteins linked to wheat bread making quality. Likewise, low temperature stress can detrimentally affect proteins in wheat. This study was done to determine the differential abundance of high molecular weight (HMW) glutenin proteins in a drought and low temperature stressed high quality hard red spring wheat cultivar (PAN3478), against a control. The treatments were applied in the greenhouse at the soft dough stage. HMW glutenin proteins were extracted from the flour, and were separated by using two-dimensional gel electrophoresis. Protein spots that had p values lower than 0.05 and fold values equal to or greater than 1.2 were considered to be significantly differentially abundant. These proteins were further analyzed by using tandem mass spectrometry. There was a 1.3 to 1.8 fold change in 17 protein spots due to the cold treatment. The drought treatment caused a 1.3 to 3.8 fold change in 19 protein spots. These spots matched either HMW or low molecular weight (LMW) glutenin subunits. In the latter case, the C subunits of LMW glutenins were notably found to be up-regulated under both stress conditions. All the proteins that have been identified can directly influence dough characteristics. Data are available via ProteomeXchange with the identifier PXD017578. [ABSTRACT FROM AUTHOR]

Durum wheat is an important crop, especially in Mediterrannean countries; around 25% of durum wheat world-wide, and 70–90% in the Middle East, is used for bread making. Climate change is causing increased periods of drought stress and higher temperatures which are affecting wheat quality. Alveograph extensibility is important for durum wheat loaf volume (LFV), as is the relationship between dough tenacity and extensibility. This study was done to identify the factors determining LFV and alveograph properties under optimal and stress conditions. Six durum wheat cultivars with the same glutenin composition were grown for two seasons under optimal, drought and heat stress conditions. Good LFV was consistently related with higher dough extensibility, irrespective of production conditions. A number of the LMW glutenin fractions, and the γ-gliadins were significantly reduced and β-gliadins were increased under both heat and drought stress. The large and total unextractable polymeric proteins and unextractable HMW glutenins were significantly reduced by heat stress. In a multiple regression of LFV (without alveograph values), solvent retention capacity and sodium dodecyl sulphate sedimentation were the best predictors of LFV under all conditions. Size-exclusion high-performance liquid chromatography fractions combined with flour protein content were good predictors of LFV only under optimal conditions. [Display omitted] • Six durum wheat cultivars were evaluated under heat and drought stress. • Quality characteristics, solvent retention capacity and gluten fractions measured. • Dough extensibility best indicator of loaf volume under all conditions. • Solvent retention capacity and SDS sedimentation good indicators of loaf volume. • SE-HPLC fractions indicator of loaf volume under non-stressed conditions. [ABSTRACT FROM AUTHOR]

Wheat grain proteins are largely affected by environmental conditions, with drought and heat stress causing considerable changes to gluten composition, resulting in variations in bread-making quality. Size-exclusion high-performance liquid chromatography (SE-HPLC) was used to assess the effects of moderate and severe drought and heat stress on variation in gluten proteins in bread wheat cultivars. Extractable gliadin (exGLi), mixing time (MixT) and total polymeric proteins (TPP) were largely genetically determined, while flour protein content (FPC) and extractable albumins/globulins (exAG) were significantly affected by treatment. The two levels of both heat and drought stress caused differential expression of gluten proteins. The unextractable polymeric proteins were reduced under severe heat stress, while both extractable and unextractable low molecular weight glutenin fractions were increased, leading to a weakening of the dough and deterioration of quality. Severe drought caused increased values of all bread-making related characteristics and loaf volume (LV), coupled with significant increases in unextractable polymeric and monomeric proteins and exGLi. Moderate heat stress caused increases in extractable HMW glutenin, which negatively affected bread-making characteristics. The large and total polymeric proteins were consistently correlated with LV for all treatments, although extractable HMW glutenins were generally negatively correlated with baking characteristics under all treatments. [Display omitted] • Two heat/drought stress intensities caused differential gluten protein expression. • Unextractable polymeric proteins reduced under severe heat. • Severe drought caused an increase in unextractable polymeric proteins. • Moderate heat stress caused increases in extractable HMW glutenin. • Large and total polymeric proteins consistently related with LV for all treatments. [ABSTRACT FROM AUTHOR]