Modelling predicts that heat stress and not drought will limit wheat yield in Europe

Global warming is characterised by shifts in weather patterns and increases in extreme weather events. New crop cultivars with specific physiological traits will therefore be required if climate change is not to result in losses of yield and food shortages. However, the intrinsic uncertainty of climate change predictions poses a challenge to plant breeders and crop scientists who have limited time and resources and must select the most appropriate traits for improvement. Modelling is, therefore, a powerful tool to identify future threats to crop production and hence targets for improvement. Wheat is the most important crop in temperate zones, including Europe, and is the staple food crop for many millions of humans and their livestock. However, its production is highly sensitive to environmental conditions, with increased temperature and incidence of drought associated with global warming posing potential threats to yield in Europe. We have therefore predicted the future impacts of these environmental changes on wheat yields using a wheat simulation model combined with climate scenarios based on fifteen global climate models from the IPCC AR4 multi-model ensemble. Despite the lower summer precipitation predicted for Europe, the impact of drought on wheat yields is likely to be smaller than at present, because the warmer conditions will result in earlier maturation before drought becomes severe later in the summer. By contrast, the probability of heat stress around flowering is predicted to increase significantly which is likely to result in considerable yield losses for heat sensitive wheat cultivars commonly grown in north Europe. Breeding strategies should therefore focus on the development of wheat varieties which are tolerant to high temperature around flowering, rather than on developing varieties resistant to drought which may be required for other parts of the world

Do ancient types of wheat have health benefits compared with modern bread wheat?

A number of studies have suggested that ancient wheats have health benefits compared with modern bread wheat. However, the mechanisms are unclear and limited numbers of genotypes have been studied, with a particular focus on Kamut (Khorasan wheat). This is important because published analyses have shown wide variation in composition between genotypes, with further effects of growth conditions. The present article therefore critically reviews published comparisons of the health benefits of ancient and modern wheats, in relation to the selection and growth of the lines, including dietary interventions and comparisons of adverse effects (allergy, intolerance, sensitivity). It is concluded that further studies are urgently required, particularly from a wider range of research groups, but also on a wider range of genotypes of ancient and modern wheat species. Furthermore, although most published studies have made efforts to ensure the comparability of material in terms of growth conditions and processing, it is essential that these are standardised in future studies and this should perhaps be a condition of publication

Modelling predicts that heat stress, not drought, will increase vulnerability of wheat in Europe

New crop cultivars will be required for a changing climate characterised by increased summer drought and heat stress in Europe. However, the uncertainty in climate predictions poses a challenge to crop scientists and breeders who have limited time and resources and must select the most appropriate traits for improvement. Modelling is a powerful tool to quantify future threats to crops and hence identify targets for improvement. We have used a wheat simulation model combined with local-scale climate scenarios to predict impacts of heat stress and drought on winter wheat in Europe. Despite the lower summer precipitation projected for 2050s across Europe, relative yield losses from drought is predicted to be smaller in the future, because wheat will mature earlier avoiding severe drought. By contrast, the risk of heat stress around flowering will increase, potentially resulting in substantial yield losses for heat sensitive cultivars commonly grown in northern Europe

Wheat glutenin subunits and dough elasticity: findings of the EUROWHEAT project

Detailed studies of wheat glutenin subunits have provided novel details of their molecular structures and interactions which allow the development of a model to explain their role in determining the visco-elastic properties of gluten and dough. The construction and analysis of near-isogenic and transgenic lines expressing novel subunit combinations or increased amounts of specific subunits allows differences in gluten properties to be related to the structures and properties of individual subunits, with potential benefits for the production of cultivars with improved properties for food processing or novel end user

What do we really understand about wheat gluten structure and functionality?

The structure and functional properties of wheat gluten have fascinated cereal chemists for over a century and a range of approaches have been taken to understand the structures and interactions of the gluten protein complex and how these are established. Nevertheless, our knowledge is still far from complete. We therefore review the current state of our knowledge and identify gaps and priorities for future research. The evidence for the forces that determine the interactions of the individual proteins in the gluten complex is re-evaluated, which allows us to define the relative contributions of covalent disulphide bonds and non-covalent forces (hydrogen bonds, hydrophobic and electrostatic interactions) and to relate these interactions to the amino acid sequences, structures and properties of the individual protein subunits. We also discuss the evidence for the pathway of gluten protein synthesis, deposition and assembly in the developing grain and how the assembly may be modified during the maturation of the grain

Development and characterisation of protein films derived from dried distillers’ grains with solubles and in-process samples

Polymer films were developed utilising proteins extracted from wheat distillers’ dried grains with solubles (DDGS) and in-process samples (wet solids), both by-products of bioethanol production process. Structural characterisation of DDGS and wet solids films indicated a change in the secondary structure of the proteins, reflecting the impact of DDGS production process such as effect of enzyme on protein properties and consequently on the film properties; whereas the developed films exhibited a rough surface with voids. Determination of moisture sensitivity indicated that DDGS films exhibited more hydrophilicity than wet solids films, with the same trend being observed for their water solubility and water uptake. The moisture content and solubility of DDGS films ranged from 10.2-14.2 % and 32.3-41.8 % respectively whereas those for wet solids’ film ranged from 18.9-19.8 % and 23.8-24.2 % respectively. The mechanical properties of DDGS and wet solids (ranging from 0.27-0.32 MPa) were comparatively lower than commercial wheat gluten film (0.6 MPa). The poor mechanical properties and high water vapour permeability of DDGS and the wet solids films limit their application as biodegradable packaging materials. However, based on their hydrophilicity, the developed films have potential applications in agriculture and horticulture as controlled release matrices and soil conditioners

Temporal and spatial control of transgene expression using a heat-inducible promoter in transgenic wheat

Constitutive promoters are widely used to functionally characterise plant genes in transgenic plants, but their lack of specificity and poor control over protein expression can be a major disadvantage. On the other hand, promoters that provide precise regulation of temporal or spatial transgene expression facilitate such studies by targeting over-expression or knockdown of target genes to specific tissues and/or at particular developmental stages. Here, we used the uidA (beta-glucuronidase, GUS) reporter gene to demonstrate that the barley Hvhsp17 gene promoter can be induced by heat treatment of 38-40 degrees C for 1-2 h in transgenic wheat. The GUS enzyme was expressed only in those tissues directly exposed to heat and not in neighbouring leaf tissues. The induction of HSP:: GUS was demonstrated in all organs and tissues tested, but expression in older tissues was lower. Generally, proximal root sections showed less GUS activity than in root tips. This heat-inducible promoter provides the ability to investigate the function of candidate genes by overexpression or by down-regulation of target gene expression (for example by RNAi) in selected tissues or developmental stages of a transgenic plant, limited only by the ability to apply a heat shock to the selected tissues. It also allows the investigation of genes that would be lethal or reduce fertility if expressed constitutively

Defining genetic and chemical diversity in wheat grain by 1H-NMR spectroscopy of polar metabolites

Scope The application of high‐throughput 1H nuclear magnetic resonance (1H‐NMR) of unpurified extracts to determine genetic diversity and the contents of polar components in grain of wheat. Methods and results Milled whole wheat grain was extracted with 80:20 D2O:CD3OD containing 0.05% d4–trimethylsilylpropionate. 1H‐NMR spectra were acquired under automation at 300°K using an Avance Spectrometer operating at 600.0528 MHz. Regions for individual metabolites were identified by comparison to a library of known standards run under identical conditions. The individual 1H‐NMR peaks or levels of known metabolites were then compared by Principal Component Analysis using SIMCA‐P software. Conclusions High‐throughput 1H‐NMR is an excellent tool to compare the extent of genetic diversity within and between wheat species, and to quantify specific components (including glycine betaine, choline, and asparagine) in individual genotypes. It can also be used to monitor changes in composition related to environmental factors and to support comparisons of the substantial equivalence of transgenic lines

The trafficking pathway of a wheat storage protein in transgenic rice endosperm

Background and Aims The trafficking of proteins in the endoplasmic reticulum (ER) of plant cells is a topic of considerable interest since this organelle serves as an entry point for proteins destined for other organelles, as well as for the ER itself. In the current work, transgenic rice was used to study the pattern and pathway of deposition of the wheat high molecular weight (HMW) glutenin sub-unit (GS) 1Dx5 within the rice endosperm using specific antibodies to determine whether it is deposited in the same or different protein bodies from the rice storage proteins, and whether it is located in the same or separate phases within these. Methods The protein distribution and the expression pattern of HMW sub-unit 1Dx5 in transgenic rice endosperm at different stages of development were determined using light and electron microscopy after labelling with antibodies. Key results The use of HMW-GS-specific antibodies showed that sub-unit 1Dx5 was expressed mainly in the sub-aleurone cells of the endosperm and that it was deposited in both types of protein body present in the rice endosperm: derived from the ER and containing prolamins, and derived from the vacuole and containing glutelins. In addition, new types of protein bodies were also formed within the endosperm cells. Conclusions The results suggest that the HMW 1Dx5 protein could be trafficked by either the ER or vacuolar pathway, possibly depending on the stage of development, and that its accumulation in the rice endosperm could compromise the structural integrity of protein bodies and their segregation into two distinct populations in the mature endosperm