Effect of high-nitrogen fertilizer on gliadin and glutenin subproteomes during kernel development in wheat (Triticum aestivum L.)

Insights into starch synthesis and amino acid composition of common buckwheat in response to phosphate fertilizer management strategies

To investigate the response and the regulatory mechanism of common buckwheat starch, amylose, and amylopectin biosynthesis to P management strategies, field experiments were conducted in 2021 and 2022 using three phosphorus (P) levels. Results revealed that the application of 75 kg hm-2 phosphate fertilizer significantly enhanced amylopectin and total starch content in common buckwheat, leading to improved grain weight and starch yield, and decreased starch granule size. The number of upregulated differentially expressed proteins induced by phosphate fertilizer increased with the application rate, with 56 proteins identified as shared differential proteins between different P levels, primarily associated with carbohydrate and amino acid metabolism. Phosphate fertilizer inhibited amylose synthesis by downregulating granule-bound starch synthase protein expression and promoted amylopectin accumulation by upregulating 1,4-alpha-glucan branching enzyme and starch synthase proteins expression. Additionally, Phosphate fertilizer primarily promoted the accumulation of hydrophobic and essential amino acids. These findings elucidate the mechanism of P-induced starch accumulation and offer insights into phosphate fertilizer management and high-quality cultivation of common buckwheat.

Nitrogen regulates the synthesis of hydrophobic amino acids to improve protein structural and gel properties in common buckwheat

Nitrogen (N) fertilizer impacts the grain quality of common buckwheat, but the effects and regulatory mechanisms of N on various protein parameters of buckwheat are not fully understood. The purpose of this study was to investigate the particle morphology, structural and gel properties, and regulation mechanism of buckwheat protein under four N levels. The bulk density, surface hydrophobicity, particle size, and thermal properties of the buckwheat protein were maximized through the optimal N application (180 kg N/ha), further enhancing the thermal stability of the protein. N application increased the β-sheet content and reduced the random coil content. Appropriate N fertilizer input enhanced the tertiary structure stability and gel elasticity of buckwheat protein by promoting hydrophobic interactions, disulfide bonds, ionic bonds, storage modulus and loss modulus. The differentially expressed proteins induced by N are primarily enriched in small ribosomal subunit and ribosome, improving protein quality mainly by promoting the synthesis of hydrophobic amino acids. Future agriculture should pay attention to the hydrophobic amino acid content of buckwheat to effectively improve protein quality. This study further advances the application of buckwheat protein in the field of food processing and provides a theoretical basis for the extensive development and utilization of buckwheat protein.

The differences in metabolites, starch structure, and physicochemical properties of rice were related to the decrease in taste quality under high nitrogen fertilizer application

Nitrogen fertilizer application is one of the key cultivation practices to improve rice yields. However, the application of high nitrogen fertilizers often leads to a reduction in the stickiness of the rice after cooking, thus reducing the taste quality of rice. Moreover, there are differences in taste quality among rice varieties, and the mechanism has not been studied in depth. In this study, two rice varieties (Meixiangzhan2hao and Exiang2hao) were planted under two nitrogen fertilizer levels. The physicochemical properties and taste quality of the rice were determined after maturity. Our results showed that high nitrogen fertilizer level alters tryptophan metabolism in rice, increasing most amino acid content and protein content in rice. The high content of protein and the higher short-range ordered structure of starch inhibited the gelatinization characteristics of starch and reduced the taste quality of rice. Under high nitrogen fertilizer application, Exiang2hao showed smaller increases in protein content, lower level of amylose and relative crystallinity, and higher content of lipid metabolites. These differences in chemical substances resulted in a less pronounced reduction in the taste quality of Exiang2hao. In this study, the taste quality of different rice varieties under different levels of nitrogen fertilizer application was analyzed, providing new ideas for future improvement of rice taste quality.

Wheat GSPs and Processing Quality Are Affected by Irrigation and Nitrogen through Nitrogen Remobilisation

The rheological properties and end-use qualities of many foods are mainly determined by the types and levels of grain storage proteins (GSPs) in wheat. GSP levels are influenced by various factors, including tillage management, irrigation, and fertiliser application. However, the effects of irrigation and nitrogen on GSPs remain unclear. To address this knowledge gap, a stationary split-split block design experiment was carried out in low- and high-fertility (LF and HF) soil, with the main plots subjected to irrigation treatments (W0, no irrigation; W1, irrigation only during the jointing stage; W2, irrigation twice during both jointing and flowering stages), subplots subjected to nitrogen application treatments (N0, no nitrogen application; N180, 180 kg/ha; N240, 240 kg/ha; N300, 300 kg/ha), and cultivars tested in sub-sub plots (FDC5, the strong-gluten cultivar Fengdecun 5; BN207, the medium-gluten cultivar Bainong 207). The results showed that GSP levels and processing qualities were significantly influenced by nitrogen application (p < 0.01), N240 was the optimal nitrogen rate, and the influence of irrigation was dependent on soil fertility. Optimal GSP levels were obtained under W2 treatment at LF conditions, and the content was increased by 17% and 16% for FDC5 and BN207 compared with W0 under N240 treatment, respectively. While the optimal GSP levels were obtained under W1 treatments at HF conditions, and the content was increased by 3% and 21% for FDC5 and BN207 compared with W0 under N240 treatment, respectively. Irrigation and nitrogen application increased the glutenin content by increasing Bx7 and Dy10 levels in FDC5, and by increasing the accumulation of Ax1 and Dx5 in BN207. Gliadins were mainly increased by enhancing α/β-gliadin levels. Correlation analysis indicated that a higher soil nitrate (NO3-N) content increased nitrogen remobilisation in leaves. Path analysis showed that Dy10, Dx5, and γ-gliadin largely determined wet glutenin content (WGC), dough stability time (DST), dough water absorption rate (DWR), and sedimentation value (SV). Therefore, appropriate irrigation and nitrogen application can improve nitrogen remobilisation, GSP levels, and processing qualities, thereby improving wheat quality and production.

Climate-Nutrient-Crop Model: Novel Insights into Grain-Based Food Quality

Mineral nutrients spatiotemporally participate in the biosynthesis and accumulation of storage biopolymers, which directly determines the harvested grain yield and quality. Optimizing fertilizer nutrient availability improves the grain yield, but quality aspects are often underestimated. We hypothesize that extensive mineral nutrients have significant effects on the biosynthesis, content, and composition of storage proteins, ultimately determining physicochemical properties and food quality, particularly in the context of climate change. To investigate this, we hierarchized 16 plant mineral nutrients and developed a novel climate-nutrient-crop model to address the fundamental question of the roles of protein and starch in grain-based food quality. Finally, we recommend increasing the added value of mineral nutrients as a socioeconomic strategy to enhance agro-food profitability, promote environmental sustainability, and improve climate resilience.

Wheat Glu-A1a encoded 1Ax1 subunit enhances gluten physicochemical properties and molecular structures that confer superior breadmaking quality

Wheat gluten proteins serve as the largest protein molecules in nature and play key roles in breadmaking quality formation. In this study, we used a pair of Glu-A1 allelic variation lines to perform a comprehensive investigation on the effects of Glu-A1a encoded 1Ax1 subunit on gluten physicochemical properties, molecular structures and breadmaking quality. The results showed that the presence of the 1Ax1 subunit significantly increased gluten content, leading to marked improvement of dough rheological properties. Meanwhile, gluten physicochemical properties such as foaming ability and foaming stability, oil/water-holding capacity, emulsifying activity, disulfide bond content, and gluten degradation temperature were significantly improved. A confocal laser scanning microscope analysis revealed that the 1Ax1 subunit drastically enhanced gluten microstructure. Gluten secondary structure analysis by Fourier transform infrared spectroscopy and laser scanning microscope-Raman spectroscopy indicated that 1Ax1 subunit significantly promoted β-turn and β-sheet content and reduced α-helix content. Three-dimensional structure analysis by AlphaFold2 revealed a similar structural feature of 1Ax1 with the superior quality subunit 1Ax2*. Correlation and principal component analyses demonstrated that α-helix and β-sheet content had a significant correlation with dough rheological properties, gluten physicochemical properties and breadmaking quality. Our results showed that 1Ax1 subunit positively affected gluten molecular structure and quality formation.

Transcriptome and Proteome Analysis Revealed the Influence of High-Molecular-Weight Glutenin Subunits (HMW-GSs) Deficiency on Expression of Storage Substances and the Potential Regulatory Mechanism of HMW-GSs

The processing quality of wheat is affected by seed storage substances, such as protein and starch. High-molecular-weight glutenin subunits (HMW-GSs) are the major components of wheat seed storage proteins (SSPs); they are also key determinators of wheat end-use quality. However, the effects of HMW-GSs absence on the expression of other storage substances and the regulation mechanism of HMW-GSs are still limited. Previously, a wheat transgenic line LH-11 with complete deletions of HMW-GSs was obtained through introducing an exogenous gene Glu-1E^bx to the wild-type cultivar Bobwhite by transgenic approach. In this study, comparative seed transcriptomics and proteomics of transgenic and non-transgenic lines at different seed developmental stages were carried out to explore the changes in genes and proteins and the underlying regulatory mechanism. Results revealed that a number of genes, including genes related to SSPs, carbohydrates metabolism, amino acids metabolism, transcription, translation, and protein process were differentially enriched. Seed storage proteins displayed differential expression patterns between the transgenic and non-transgenic line, a major rise in the expression levels of gliadins were observed at 21 and 28 days post anthesis (DPA) in the transgenic line. Changes in expressions of low-molecular-weight glutenins (LMW-GSs), avenin-like proteins (ALPs), lipid transfer proteins (LTPs), and protease inhibitors (PIs) were also observed. In addition, genes related to carbohydrate metabolism were differentially expressed, which probably leads to a difference in starch component and deposition. A list of gene categories participating in the accumulation of SSPs was proposed according to the transcriptome and proteome data. Six genes from the MYB and eight genes from the NAC transcription families are likely important regulators of HMW-GSs accumulation. This study will provide data support for understanding the regulatory network of wheat storage substances. The screened candidate genes can lay a foundation for further research on the regulation mechanism of HMW-GSs.

Does Nitrogen Fertilization Affect the Secondary Structures of Gliadin Proteins in Hypoallergenic Wheat?

One of the macronutrients indispensable for plant growth and development is nitrogen (N). It is responsible for starch and storage protein (gliadins and glutenins) biosynthesis and, in consequence, influences kernels’ quality and yields. However, applying N-fertilizers increases gluten content in wheat, and it may intensify the risk of developing allergy symptoms in gluten-sensitive individuals. The purpose of our research was to analyse whether and how the elimination of N-fertilizers during the cultivation of wasko.gl− wheat (modified genotype lacking ω-gliadins) changes the secondary structures of gliadin proteins. To this aim, using the FT-Raman technique, we examined flour and gliadin protein extracts obtained from kernels of two winter wheat lines: wasko.gl+ (with a full set of gliadin proteins) and wasko.gl− (without ω-gliadin fraction) cultivated on two different N-fertilization levels—0 and 120 kg N·ha⁻¹. On the basis of the obtained results, we proved that nitrogen fertilization does not have a major impact on the stability of the secondary structures of gliadin proteins for wasko.gl− wheat line with reduced allergenic properties. Furthermore, the results presented herein suggest the possibility of increasing the stability of glutenin structures as a result of the N-fertilization of wasko.gl− wheat line, which gives hope for its use in the production of wheat articles devoted to people suffering from diseases related to gluten sensitivity.

Growth, Yield and Photosynthetic Performance of Winter Wheat as Affected by Co-Application of Nitrogen Fertilizer and Organic Manures

The application of organic manures was found to be beneficial, however, the integrated use of organic manures with chemical nitrogen fertilizers has proven more sustainable in increasing the photosynthetic attributes and grain yield of the winter-wheat crop. A multi-factor split-plot design was adopted, nitrogen and manure fertilizer treatments were set in the sub-plots, including nitrogen-gradient treatment of T1:0 kg N ha⁻¹, T2:100 kg N ha⁻¹, T3:200 kg N ha⁻¹, and T4:300 kg N ha⁻¹ (pure nitrogen -fertilizer application) The 25% reduction in nitrogen combined with the manure-fertilizer application includes T5:75 kg N ha⁻¹ nitrogen and 25 kg N ha⁻¹ manure, T6:150 kg N ha⁻¹ nitrogen and 50 kg N ha⁻¹ manure, and T7:225 kg N ha⁻¹ nitrogen and 75 kg N ha⁻¹ manure. The maximum results of the total chlorophyll content and photosynthetic rate were 5.73 mg/g FW and 68.13 m mol m⁻² s⁻¹, observed under T4 in Zhongmai 175, as compared to Jindong 22 at the heading stage. However, the maximum results of intercellular CO₂ concentration were 1998.47 μmol mol⁻¹, observed under T3 in Jindong 22, as compared to Zhongmai 175 at the tillering stage. The maximum results of LAI were 5.35 (cm²), observed under T7 in Jindong 22, as compared to Zhongmai 175 at the booting stage. However, the maximum results of Tr and Gs were 6.31 mmol H₂O m⁻² s⁻¹ and 0.90 H₂O mol m⁻² s⁻¹, respectively, observed under T7 in Zhongmai 175 as compared to Jindong 22 at the flowering stage. The results revealed that grain yield 8696.93 kg ha⁻¹, grains spike⁻¹ 51.33 (g), and 1000-grain weight 39.27 (g) were significantly higher, under T3 in Zhongmai 175, as compared to Jindong 22. Moreover, the spike number plot⁻¹ of 656.67 m² was significantly higher in Jindong 22, as compared to Zhongmai 175. It was concluded from the study that the combined application of nitrogen and manure fertilizers in winter wheat is significant for enhancing seed at the jointing and flowering stages. For increased grain yield and higher economic return, Zhongmai 175 outperformed the other cultivars examined. This research brings awareness toward the nitrogen-fertilizer-management approach established for farmers’ practice, which might be observed as an instruction to increase agricultural management for the winter-wheat-growth season.

Barriers and levers to enhance end-use functional properties of durum wheat (Triticum turgidum L.) grain: An agronomic implication

The current trends in population growth and consumption pattern remain to increase the demand for durum wheat grain. However, multiple biotic and abiotic challenges due to climate change coupled with crop management practices possess major concern to improve durum wheat production and storage proteins. Efforts on developing innovative agronomic and breeding strategies are essential to enhance productivity, and nutritional quality under the changing climate. Nitrogen is an important structural component of protein, and potentially reduce the adverse effect of drought stress through maintaining metabolic activities. Optimum nitrogen fertilization allows durum wheat producing farmers to attain high quality yield, brings economic benefit, and reduces environmental pollution. However, defining an optimum nitrogen fertilizer rate for specific location requires considering yield achievement and quality of the end products. If the producers interest is, geared towards production of high protein content, high nitrogen dose is required. If the interest gears towards grain yield improvement optimization of nitrogen fertilizer rate is important. This indicates that defining product-specific nitrogen application is required for sustainable durum wheat production. Therefore, future challenges of increasing production, productivity, and end-use functional properties of durum wheat will only be achieved through cooperation of multidisciplinary teams who are able to incorporate new technologies.

Wheat Quality Formation and Its Regulatory Mechanism

Elucidation of the composition, functional characteristics, and formation mechanism of wheat quality is critical for the sustainable development of wheat industry. It is well documented that wheat processing quality is largely determined by its seed storage proteins including glutenins and gliadins, which confer wheat dough with unique rheological properties, making it possible to produce a series of foods for human consumption. The proportion of different gluten components has become an important target for wheat quality improvement. In many cases, the processing quality of wheat is closely associated with the nutritional value and healthy effect of the end-products. The components of wheat seed storage proteins can greatly influence wheat quality and some can even cause intestinal inflammatory diseases or allergy in humans. Genetic and environmental factors have great impacts on seed storage protein synthesis and accumulation, and fertilization and irrigation strategies also greatly affect the seed storage protein content and composition, which together determine the final end-use quality of wheat. This review summarizes the recent progress in research on the composition, function, biosynthesis, and regulatory mechanism of wheat storage proteins and their impacts on wheat end-product quality.

Wheat Breeding, Fertilizers, and Pesticides: Do They Contribute to the Increasing Immunogenic Properties of Modern Wheat?

Celiac disease (CD) is a small intestinal inflammatory condition where consumption of gluten induces a T-cell mediated immune response that damages the intestinal mucosa in susceptible individuals. CD affects at least 1% of the world’s population. The increasing prevalence of CD has been reported over the last few decades. However, the reason for this increase is not known so far. Certain factors such as increase in awareness and the development of advanced and highly sensitive diagnostic screening markers are considered significant factors for this increase. Wheat breeding strategies, fertilizers, and pesticides, particularly herbicides, are also thought to have a role in the increasing prevalence. However, less is known about this issue. In this review, we investigated the role of these agronomic practices in depth. Our literature-based results showed that wheat breeding, use of nitrogen-based fertilizers, and herbicides cannot be solely responsible for the increase in celiac prevalence. However, applying nitrogen fertilizers is associated with an increase in gluten in wheat, which increases the risk of developing celiac-specific symptoms in gluten-sensitive individuals. Additionally, clustered regularly interspaced short palindromic repeats (CRISPR) techniques can edit multiple gliadin genes, resulting in a low-immunogenic wheat variety that is safe for such individuals.

Proteomics characterization nitrogen fertilizer promotes the starch synthesis and metabolism and amino acid biosynthesis in common buckwheat

Nitrogen (N) affects common buckwheat quality by affecting starch and amino acids (AAs) content, but its molecular mechanism is still unclear. We selected two common buckwheat varieties with high and low starch content, and designed two treatments with 180 and 0 kg N/ha. Application of high-N led to significant increases in starch, amylose and amylopectin content. Of 1337 differentially expressed proteins (DEPs) induced by high-N conditions. 472DEPs were significantly upregulated and 176DEPs downregulated for Xinong9976. 239DEPs were significantly upregulated and 126DEPs downregulated for Beizaosheng. The six alpha-glucan phosphorylases, three alpha-amylases, one granule-bound starch synthase 1 and one sucrose synthase exhibited higher expression at the 180 kg N/ha than at the 0 kg N/ha. In addition, high-N application promoted arginine, leucine, isoleucine and valine biosynthesis. This study revealed the effect of N on the starch and AA content of common buckwheat and its mechanism. The crucial proteins identified may develop the quality of common buckwheat.

The effect of nitrogen fertilization on the expression of protein in wheat and tritordeum varieties using a proteomic approach

Wheat, an essential ingredient for several bakery preparations, is also responsible for gluten-related diseases in sensitive subjects. The effect of the N fertilization rate (80 vs 160 kg N ha^-1) on gluten protein expression profile has been evaluated considering two soft wheats (landrace and modern) and one tritordeum cultivar (cv), grown in the same experimental field in North Italy. The proteins of refined flour were characterized through advanced proteomic approaches, including chromatography (RP-HPLC) and electrophoresis. A static model system was used to simulate in vitro digestion and the digestome peptides were examined by mass spectrometry and in silico approaches, to investigate the celiac and allergenic sequences. The CD-toxic epitopes in the digested samples were quantified by means of a R5 ELISA assay. The N fertilization rate increased the grain protein content, but it did not lead to any difference in gluten composition, with exception of glu/glia ratio in the modern wheat cv. Moreover, the gluten composition and the occurrence of toxic/allergenic epitopes varied to a great extent, according mostly to the genotype. A lower immunoreactivity, determined using R5 ELISA, was detected for the digested tritordeum flours than for the landrace (-51%) or modern (-58%) cvs, while no significant difference was observed for the N rates between each genotype. In silico analysis showed that tritordeum has fewer CD epitopes belonging to the ω-gliadins and a lower LMW-GS than the landrace or modern cv. Tritordeum presented fewer α-gliadin allergenic epitopes than the modern wheat cv. The lower frequency of celiac epitopes in tritordeum, compared to the old and the modern wheat, is probably due to the absence of a D genome.

Proteomics unravels new candidate genes of Dasypyrum villosum for improving wheat quality

Wheat is one of the most widely grown and important food crops in the world, providing approximately 20% of the food energy and protein produced for human consumption. The progress of wheat breeding is seriously restricted by the narrow genetic basis of common wheat germplasms. Dasypyrum villosum, a wild grass species that is commonly used in wheat improvement, has many excellent traits such as disease resistance, drought resistance, cold resistance, strong tillering ability, and processing quality. In this study, we compared and analyzed the cultivated wheat variety Chinese Spring (CS) and D. villosum using comparative proteomics. A total of 883 different abundant proteins (DAPs) were identified. Some of these different abundant proteins are associated with defense and stress, such as the G_α subunit, zinc finger protein family, PR1, HSP family, LEA protein, and serpin family. And a total of 24 different abundant proteins are gluten proteins. There are also 24 different abundant proteins associated with starch and sucrose metabolism. These results will provide potential candidate genes and a foundation for further research on resistance and quality for wheat genetics and breeding. SIGNIFICANCE: Proteins are the direct functional molecules of living organisms. It is of great significance to study the function of plant related genes from the perspective of protein. In this study, proteomics methods based on iTRAQ were used to compare the proteomic differences between wheat varieties Chinese Spring (CS) and D. villosum. The results provide novel insight into improving the quality of wheat. It is helpful to search for potential candidate genes for improving wheat quality and elucidate the molecular mechanisms associated with these genes.

The α-Gliadins in Bread Wheat: Effect of Nitrogen Treatment on the Expression of the Major Celiac Disease Immunogenic Complex in Two RNAi Low-Gliadin Lines

Celiac Disease (CD) is an autoimmune disorder that affects approximately 1% of the worldwide population. The α-gliadins of wheat contain the 33-mer peptide, the most active peptide in CD both in adults and pediatric patients. In this study, we have characterized the variants and expression profile of an α-gliadins amplicon, harboring the 33-mer peptide, in two low-gliadin RNAi wheat lines, under two different Nitrogen (N) treatments. We estimated that the amplicon expands 45 different α-gliadin variants with high variability due to length, randomly distributed SNPs, and the presence of encoded CD epitopes. Expression of this amplicon is reduced in both RNAi lines in comparison to the wild type. High N treatment significantly increases transcripts of the amplicon in the wild type, but not in the transgenic lines. Classification of α-gliadin variants, considering the number of epitopes, revealed that amplicon variants containing the full complement of 33-mer peptide were affected by N treatment, increasing their expression when N was increased. Line D793 provided higher and more stable silencing through different N fertilization regimes, expressing fewer CD epitopes than D783. Results of this study are important for better understanding of RNAi α-gliadin silencing in response to N treatments, and for undertaking new strategies by RNAi or CRISPR/Cas toward obtaining new varieties suitable for people suffering gluten intolerances.

Identification of stress defensive proteins in common wheat-Thinopyron intermedium translocation line YW642 developing grains via comparative proteome analysis

Thinopyrum intermedium (2n = 6x = 42, E1E1E2E2XX) serves as an important gene source of desirable traits for genetic improvement of wheat cultivars resistant to stresses. This study used the comparative proteomic approach to identify stress defense related proteins in the developing grains of common wheat (Zhongmai 8601)-Thinopyron intermedium 7XL/7DS translocation line YW642 and to explore their potential values for improving wheat stress resistance. Two-dimensional electrophoresis identified 124 differentially accumulated protein spots representing 100 unique proteins, which mainly participated in stress defense, energy metabolism, protein metabolism and folding and storage protein synthesis. Among these, 16 were unique and 35 were upregulated in YW642. The upregulated DAPs were mainly involved in biotic and abiotic stress defense. Further cis-elements analysis of these stress-related DAP genes revealed that phytohormone responsive elements such as ABREs, G-box, CGTCA-motif and TGACG-motif, and environment responsive element As-1 were particularly abundant, which could play important roles in response to various stressors. Transcription expression analysis by RNA-seq and qRT-PCR demonstrated a large part of the stress-related DAP genes showed an upregulated expression in the early-to-middle stages of grain development. Our results proved that Thinopyron intermedium contains abundant stress responsive proteins that have potential values for the genetic improvement of wheat stress resistance.

Could Global Intensification of Nitrogen Fertilisation Increase Immunogenic Proteins and Favour the Spread of Coeliac Pathology?

Fertilisation of cereal crops with nitrogen (N) has increased in the last five decades. In particular, the fertilisation of wheat crops increased by nearly one order of magnitude from 1961 to 2010, from 9.84 to 93.8 kg N ha-1 y-1. We hypothesized that this intensification of N fertilisation would increase the content of allergenic proteins in wheat which could likely be associated with the increased pathology of coeliac disease in human populations. An increase in the per capita intake of gliadin proteins, the group of gluten proteins principally responsible for the development of coeliac disease, would be the responsible factor. We conducted a global meta-analysis of available reports that supported our hypothesis: wheat plants growing in soils receiving higher doses of N fertilizer have higher total gluten, total gliadin, α/β-gliadin, γ-gliadin and ω-gliadin contents and higher gliadin transcription in their grain. We thereafter calculated the per capita annual average intake of gliadins from wheat and derived foods and found that it increased from 1961 to 2010 from approximately 2.4 to 3.8 kg y-1 per capita (+1.4 ± 0.18 kg y-1 per capita, mean ± SE), i.e., increased by 58 ± 7.5%. Finally, we found that this increase was positively correlated with the increase in the rates of coeliac disease in all the available studies with temporal series of coeliac disease. The impacts and damage of over-fertilisation have been observed at an environmental scale (e.g., eutrophication and acid rain), but a potential direct effect of over-fertilisation is thus also possible on human health (coeliac disease).

Dynamic proteome changes of wheat developing grains in response to water deficit and high-nitrogen fertilizer conditions

This study investigated grain proteomic profiles in response to water deficit, high nitrogen (N) fertilizer, and their combined treatments in elite Chinese bread wheat cultivar Jingdong 17, using a two-dimensional difference gel electrophoresis (2D-DIGE)-based approach. Water deficit negatively affected the main agronomic traits of wheat and grain yield, while high-N fertilizer had the opposite effects. The application of a high-N fertilizer under water deficit conditions moderately improved kernel development and grain yield. 2D-DIGE led to the identification of 124 differentially accumulated protein (DAP) spots during five different grain developmental stages, corresponding to 97 unique proteins. The more significant changes of DAPs occurred at 10-20 days after flowering. DAPs were involved in carbohydrate metabolism, protein turnover, protein folding, cell cycle control, stress response, nitrogen metabolism, photosynthesis, and energy metabolism. In particular, water deficit caused a significant downregulation of proteins involved in starch biosynthesis, whereas high-N fertilizer led to a significant upregulation of proteins involved in nitrogen metabolism, carbohydrate metabolism, and starch biosynthesis. The combined treatment resulted in a moderate upregulation of DAPs related to carbohydrate metabolism, starch biosynthesis, and nitrogen metabolism. Our results indicated that high-N fertilization could alleviate yield loss caused by water deficit by promoting the accumulation of proteins involved in nitrogen and carbohydrate metabolism.

Effects of Independent and Combined Water-Deficit and High-Nitrogen Treatments on Flag Leaf Proteomes during Wheat Grain Development

We present the first comprehensive proteome analysis of wheat flag leaves under water-deficit, high-nitrogen (N) fertilization, and combined treatments during grain development in the field. Physiological and agronomic trait analyses showed that leaf relative water content, total chlorophyll content, photosynthetic efficiency, and grain weight and yield were significantly reduced under water-deficit conditions, but dramatically enhanced under high-N fertilization and moderately promoted under the combined treatment. Two-dimensional electrophoresis detected 72 differentially accumulated protein (DAP) spots representing 65 unique proteins, primarily involved in photosynthesis, signal transduction, carbohydrate metabolism, redox homeostasis, stress defense, and energy metabolism. DAPs associated with photosynthesis and protein folding showed significant downregulation and upregulation in response to water-deficit and high-N treatments, respectively. The combined treatment caused a moderate upregulation of DAPs related to photosynthesis and energy and carbohydrate metabolism, suggesting that high-N fertilization can alleviate losses in yield caused by water-deficit conditions by enhancing leaf photosynthesis and grain storage compound synthesis.