Low protein wheat for bread making

Nitrogen (N) is the major mineral that determines crop yield, but it is also an important determinant of grain quality, particularly in wheat. It is required for the synthesis of grain proteins, with gluten forming the major protein fraction in wheat grain. Because of the high protein content required for bread making, the requirement for N applied to bread-making wheats may be above the optimum required for yield, by up to 50 kg N/ha. For example, Dampney et al. (1995) reported that to produce grain containing 13% protein, about 60 kgN/ha above the yield optimum was required. N fertiliser is a major cost for farmers, with a high-energy requirement for manufacture and potentially harmful environmental footprint. Therefore, it is important to reduce the requirement for producing breadmaking wheat, either by improving the efficiency of N use within the plant or by developing new types of wheat that allow the use of lower protein contents for bread making. This project focused on the latter strategy. It aimed to identify and characterise types of wheat with good bread-making quality at low grain protein content. Forty wheat genotypes were grown on 6 sites for 2 years, with a sub-set of 30 grown on the same sites for a third year. All were grown in 3 randomised replicate plots and at 2 levels of N fertilisation: 150 kgN/ha (low) and 250 kgN/ha (conventional). This generated over 4000 grain samples that were analysed for protein content. Samples from 4 sites were bulked for detailed analysis, excluding sites associated with technical problems or unusually high or low contents of protein or responses to fertilisation. Whereas all 40 genotypes were studied in the first year, the number was reduced to 30 in year 2 and to 20 in year 3, based on the analysis of the samples from years 1 and 2, respectively. Campden BRI milled the samples and carried out Extensograph and Farinograph analyses of all flours. The mixing and bread-making performances were subsequently determined by 6 commercial partners, who used three different bread-making processes. SE-HPLC analyses of gluten polymer size distribution was determined on all samples from year 1 and the low N samples from years 2 and 3. This comparison showed that five cultivars (called Group 1) performed well at both high and low N and over all three years: Crusoe and Gallant (current UK nabim Group 1), Rumor and Nelson (German varieties bred to show high quality at low grain protein) and Genius (Danish bread-making cultivar). In addition, two cultivars (called Group 2) performed better when grown at low N than at high N: Skyfall (current UK nabim Group 1 cultivar) and Mv Lucilla (Hungarian high protein breadmaking cultivar). A comparison between these two groups of cultivars and the whole set of cultivars was carried out focusing on four parameters: grain N, grain protein deviation (GPD), gluten protein profiles by SE-HPLC and dough rheology (R/E) measured by Extensograph. This showed that: 1. The selected (Groups 1 and 2) wheats had higher %N, GPD, dough elasticity and proportions of glutenin polymers ((%F1+%F2)/(%F3+%F4)) than the non-selected cultivars. 2. In addition, the Group 2 wheats (which performed better at low N) had higher proportions of high molecular weight glutenin polymers (%F1, (%F3+%F4)/%F1). Although these cultivars include two German lines bred to perform well at low N, they also include three highly successful recent UK cultivars: Crusoe, Gallant and Skyfall. Hence, modern cultivars, which have been selected for performance in high-input systems, may also perform well under low N inputs. We conclude that good bread-making performance at low N fertiliser resulted from two factors: efficient translocation of N into the grain and increased proportions of glutenin in gluten, which resulted in greater dough elasticity. Breeding should, therefore, focus on increasing the efficiency of N use combined with high gluten protein elasticity

Energy utilization and growth performance of chickens fed novel wheat inbred lines selected for different pentosan levels with and without xylanase supplementation

Different F5 recombinant inbred lines from the cross Yumai 34 × Ukrainka were grown in replicated trials on a single site in one harvest year at Rothamsted Research. A total of 10 samples from those lines were harvested and used in a broiler experiment. Twenty nutritionally complete meal-form diets that had 630 g/kg of wheat with different amounts of pentosan, with and without exogenous xylanase supplementation, were used to compare broiler growth performance and determine apparent metabolizable energy corrected for N retention (AMEn). We examined the relationship between the nutritive value of the wheat samples and their chemical compositions and results of quality tests. The amounts of total and water soluble pentosans in wheat samples ranged from 36.7 to 48.0 g/kg DM, and 6.7 to 11.6 g/kg DM, respectively. The mean crude oil and protein contents of the wheat samples were 10.5 and 143.9 g/kg DM, respectively. The average determined value for the kinematic viscosity was 0.0018 mPa.s, and 2.1 mPa.s for the dynamic viscosity. The AMEn of the wheat-based diets had a maximum range of 0.47 MJ/kg DM within the ten wheat samples that were tested. Xylanase supplementation improved (P < 0.05) dietary AMEn, dry matter, and fat digestibility coefficients. There was a positive (P < 0.05) relationship between in vitro kinematic viscosity of the wheat samples and the total pentosan content. There was a negative relationship between the total pentosan content in the wheat and broiler growth performance. An increase by 10 g of pentosan per kg of wheat reduced (P < 0.001) daily feed intake and weight gain by 2.9 g and 3.5 g, respectively. The study shows that the feeding quality of wheat samples can be predicted by their total pentosan content. Supplementary xylanase improved energy and nutrient availability of all wheat samples that was independent of differences in pentosan content

Comparative Compositions of Grain of Bread Wheat, Emmer and Spelt Grown with Different Levels of Nitrogen Fertilisation

Five cultivars of bread wheat and spelt and three of emmer were grown in replicate randomised field trials on two sites for two years with 100 and 200 kg nitrogen fertiliser per hectare, reflecting low input and intensive farming systems. Wholemeal flours were analysed for components that are suggested to contribute to a healthy diet. The ranges of all components overlapped between the three cereal types, reflecting the effects of both genotype and environment. Nevertheless, statistically significant differences in the contents of some components were observed. Notably, emmer and spelt had higher contents of protein, iron, zinc, magnesium, choline and glycine betaine, but also of asparagine (the precursor of acrylamide) and raffinose. By contrast, bread wheat had higher contents of the two major types of fibre, arabinoxylan (AX) and _-glucan, than emmer and a higher AX content than spelt. Although such differences in composition may be suggested to result in effects on metabolic parameters and health when studied in isolation, the final effects will depend on the quantity consumed and the composition of the overall diet

Identification of Traits Underpinning Good Breadmaking Performance of Wheat Grown with Reduced Nitrogen Fertilisation

Background: Nitrogen fertiliser is the major input and cost for wheat production, being required to support the development of the canopy to maximise yield and for the synthesis of the gluten proteins that are necessary for breadmaking. Consequently, current high-yielding cultivars require the use of nitrogen fertilisation levels above the yield optimum to achieve the grain protein content needed for breadmaking. This study aimed to reduce this requirement by identifying traits that allow the use of lower levels of nitrogen fertiliser to produce wheat for breadmaking. Results: A range of commercial wheat genotypes (cultivars) were grown in multiple field trials (six sites over 3 years) in the UK with optimal (200 kg Ha-1) and suboptimal (150 kg Ha-1) application of nitrogen. Bulked grain samples from four sites per year were milled and white flours were baked using three types of breadmaking process. This identified five cultivars that consistently exhibited good breadmaking quality when grown with the lower nitrogen application. Chemical and biochemical analyses showed that the five cultivars were characterised by exhibiting grain protein deviation (GPD) and high dough elasticity. Conclusions: It is possible to develop novel types of wheat that exhibit good breadmaking quality by selecting for GPD and high dough strengt

The reductive activation of CO2 across a Ti═Ti double bond: synthetic, structural, and mechanistic studies

[Image: see text] The reactivity of the bis(pentalene)dititanium double-sandwich compound Ti(2)Pn(†)(2) (1) (Pn(†) = 1,4-{Si(i)Pr(3)}(2)C(8)H(4)) with CO(2) is investigated in detail using spectroscopic, X-ray crystallographic, and computational studies. When the CO(2) reaction is performed at −78 °C, the 1:1 adduct 4 is formed, and low-temperature spectroscopic measurements are consistent with a CO(2) molecule bound symmetrically to the two Ti centers in a μ:η(2),η(2) binding mode, a structure also indicated by theory. Upon warming to room temperature the coordinated CO(2) is quantitatively reduced over a period of minutes to give the bis(oxo)-bridged dimer 2 and the dicarbonyl complex 3. In situ NMR studies indicated that this decomposition proceeds in a stepwise process via monooxo (5) and monocarbonyl (7) double-sandwich complexes, which have been independently synthesized and structurally characterized. 5 is thermally unstable with respect to a μ-O dimer in which the Ti–Ti bond has been cleaved and one pentalene ligand binds in an η(8) fashion to each of the formally Ti(III) centers. The molecular structure of 7 shows a “side-on” bound carbonyl ligand. Bonding of the double-sandwich species Ti(2)Pn(2) (Pn = C(8)H(6)) to other fragments has been investigated by density functional theory calculations and fragment analysis, providing insight into the CO(2) reaction pathway consistent with the experimentally observed intermediates. A key step in the proposed mechanism is disproportionation of a mono(oxo) di-Ti(III) species to yield di-Ti(II) and di-Ti(IV) products. 1 forms a structurally characterized, thermally stable CS(2) adduct 8 that shows symmetrical binding to the Ti(2) unit and supports the formulation of 4. The reaction of 1 with COS forms a thermally unstable complex 9 that undergoes scission to give mono(μ-S) mono(CO) species 10. Ph(3)PS is an effective sulfur transfer agent for 1, enabling the synthesis of mono(μ-S) complex 11 with a double-sandwich structure and bis(μ-S) dimer 12 in which the Ti–Ti bond has been cleaved

A Genome Wide Association Study of arabinoxylan content in 2-row spring barley grain

In barley endosperm arabinoxylan (AX) is the second most abundant cell wall polysaccharide and in wheat it is the most abundant polysaccharide in the starchy endosperm walls of the grain. AX is one of the main contributors to grain dietary fibre content providing several health benefits including cholesterol and glucose lowering effects, and antioxidant activities. Due to its complex structural features, AX might also affect the downstream applications of barley grain in malting and brewing. Using a high pressure liquid chromatography (HPLC) method we quantified AX amounts in mature grain in 128 spring 2-row barley accessions. Amounts ranged from ~ 5.2 μg/g to ~ 9 μg/g. We used this data for a Genome Wide Association Study (GWAS) that revealed three significant quantitative trait loci (QTL) associated with grain AX levels which passed a false discovery threshold (FDR) and are located on two of the seven barley chromosomes. Regions underlying the QTLs were scanned for genes likely to be involved in AX biosynthesis or turnover, and strong candidates, including glycosyltransferases from the GT43 and GT61 families and glycoside hydrolases from the GH10 family, were identified. Phylogenetic trees of selected gene families were built based on protein translations and were used to examine the relationship of the barley candidate genes to those in other species. Our data reaffirms the roles of existing genes thought to contribute to AX content, and identifies novel QTL (and candidate genes associated with them) potentially influencing the AX content of barley grain. One potential outcome of this work is the deployment of highly associated single nucleotide polymorphisms markers in breeding programs to guide the modification of AX abundance in barley grain

Chemical PARP Inhibition Enhances Growth of Arabidopsis and Reduces Anthocyanin Accumulation and the Activation of Stress Protective Mechanisms

Poly-ADP-ribose polymerase (PARP) post-translationally modifies proteins through the addition of ADP-ribose polymers, yet its role in modulating plant development and stress responses is only poorly understood. The experiments presented here address some of the gaps in our understanding of its role in stress tolerance and thereby provide new insights into tolerance mechanisms and growth. Using a combination of chemical and genetic approaches, this study characterized phenotypes associated with PARP inhibition at the physiological level. Molecular analyses including gene expression analysis, measurement of primary metabolites and redox metabolites were used to understand the underlying processes. The analysis revealed that PARP inhibition represses anthocyanin and ascorbate accumulation under stress conditions. The reduction in defense is correlated with enhanced biomass production. Even in unstressed conditions protective genes and molecules are repressed by PARP inhibition. The reduced anthocyanin production was shown to be based on the repression of transcription of key regulatory and biosynthesis genes. PARP is a key factor for understanding growth and stress responses of plants. PARP inhibition allows plants to reduce protection such as anthocyanin, ascorbate or Non-Photochemical-Quenching whilst maintaining high energy levels likely enabling the observed enhancement of biomass production under stress, opening interesting perspectives for increasing crop productivity