小麦-卵穗山羊草1Mg异附加系蛋白质品质形成解析

为了突破小麦品质育种瓶颈,从小麦的近缘属种中挖掘优质蛋白亚基,并解析优质亚基的品质效应,本研究选取中国春(CS)及CS与卵穗山羊草1Mg异附加系(CS-1Mg)作为试验材料,研究其亚基组成、籽粒发育过程中的谷蛋白聚合体动态积累、面筋蛋白的微观结构与二级结构、面团的混揉特性等以解析异源染色体的加入对面团品质形成的影响。结果表明,与CS相比,CS-1Mg中出现了新型HMW-GS,使其在籽粒发育过程中UPP快速积累,面筋蛋白呈现出更好的二级结构分布,微观结构上蛋白质交织更紧密,流变学特性及混揉特性增强,品质显著提高。CS-1Mg所携带的新型HMW-GS可以作为优质基因源用于优质小麦育种,CS-1Mg可作为中间材料应用于小麦品质改良的生产实践中。     

Improving wheat to remove coeliac epitopes but retain functionality

Coeliac disease is an intolerance triggered by the ingestion of wheat gluten proteins. It is of increasing concern to consumers and health professionals as its incidence appears to be increasing. The amino acid sequences in gluten proteins that are responsible for triggering responses in sensitive individuals have been identified showing that they vary in distribution among and between different groups of gluten proteins. Conventional breeding may therefore be used to select for gluten protein fractions with lower contents of coeliac epitopes. Molecular breeding approaches can also be used to specifically down-regulate coeliac-toxic proteins or mutate coeliac epitopes within individual proteins. A combination of these approaches may therefore be used to develop a “coeliac-safe” wheat. However, this remains a formidable challenge due to the complex multigenic control of gluten protein composition. Furthermore, any modified wheats must retain acceptable properties for making bread and other processed foods. Not surprisingly, such coeliac-safe wheats have not yet been developed despite over a decade of research.     

Genetic and environmental factors affecting pathogenicity of wheat as related to celiac disease

Gluten proteins are the basis of the rheological properties of wheat derived products, such as bread and pasta. Their particular amino acidic composition (high proline and glutamine content) is responsible for the poor gluten digestibility. Some of the high molecular weight peptides that are generated in the gastrointestinal tract are involved in an autoimmune entheropathy called celiac disease. In this work we compared the amount of peptides containing sequences involved in adaptive and immune responses, which were produced after simulated gastrointestinal digestion of prolamins extracted from different durum wheat varieties and in-bred lines. Peptides containing sequences involved in celiac disease were quantified using an isotopically labeled peptide as internal standard. The results demonstrated a very high variability in the amount of pathogenic peptides produced by different lines, showing a strong contribution of the genetic component. At the same time, the variability in total protein and gluten content was lower; the weak correlation between pathogenic peptides and the amount of gluten proteins gives rise to the possibility of a varietal selection aimed to maintain good rheological properties, but simultaneously reducing the exposure to peptides eliciting an immunological response in celiac predisposed subjects. These varieties might be useful for celiac disease prevention.     

Using the Gluten Peak Tester as a tool to measure physical properties of gluten

The functional properties of wheat are largely dictated by composition and interactions of the gluten proteins. All flours contain gliadin and glutenin, but produce baked products of varying quality, which provides evidence that gluten proteins from different wheats possess different properties. A common method to study differences in gluten properties, which is utilized in this study, is fractionation/reconstitution experiments to understand how various gliadin to glutenin ratios and how fractions from different wheat sources affect gluten aggregation properties. Gliadin and glutenin from a vital wheat gluten were fractionated with 70% ethanol and reconstituted at various gliadin to glutenin ratios. Gliadin and glutenin from a Canadian eastern soft, eastern hard and western hard wheat (14% moisture) were fractionated and substituted between flours at the native gliadin to glutenin ratio. Gluten combinations were evaluated with a Gluten Peak Tester at constant temperature and mixing. Varying gliadin to glutenin ratio showed that 50:50 is optimal for fast gluten aggregation while amount of glutenin dictates strength. Substitution experiments showed that replacing good quality gluten fractions with those from a lower quality wheat decreases gluten quality, and vice versa. Data also showed that cultivar specific differences in gliadin and glutenin are more important in dictating gluten strength (torque), while gliadin to glutenin ratio dictates aggregation time (PMT) independent of the source of fractions. The study demonstrated the ability of the improved method to evaluate gluten aggregation by controlling for all variables except the one being tested. The data also revealed information about gluten aggregation properties never before seen.     

Using the Gluten Peak Tester as a tool to measure physical properties of gluten

The functional properties of wheat are largely dictated by composition and interactions of the gluten proteins. All flours contain gliadin and glutenin, but produce baked products of varying quality, which provides evidence that gluten proteins from different wheats possess different properties. A common method to study differences in gluten properties, which is utilized in this study, is fractionation/reconstitution experiments to understand how various gliadin to glutenin ratios and how fractions from different wheat sources affect gluten aggregation properties. Gliadin and glutenin from a vital wheat gluten were fractionated with 70% ethanol and reconstituted at various gliadin to glutenin ratios. Gliadin and glutenin from a Canadian eastern soft, eastern hard and western hard wheat (14% moisture) were fractionated and substituted between flours at the native gliadin to glutenin ratio. Gluten combinations were evaluated with a Gluten Peak Tester at constant temperature and mixing. Varying gliadin to glutenin ratio showed that 50:50 is optimal for fast gluten aggregation while amount of glutenin dictates strength. Substitution experiments showed that replacing good quality gluten fractions with those from a lower quality wheat decreases gluten quality, and vice versa. Data also showed that cultivar specific differences in gliadin and glutenin are more important in dictating gluten strength (torque), while gliadin to glutenin ratio dictates aggregation time (PMT) independent of the source of fractions. The study demonstrated the ability of the improved method to evaluate gluten aggregation by controlling for all variables except the one being tested. The data also revealed information about gluten aggregation properties never before seen.     

Variability and cluster analysis of arabinoxylan content and its molecular profile in crossed wheat lines

Non-starch polysaccharides (NSP) in cereals, after starch and gluten proteins, determine the technological and nutritional properties of flour, dough and end product. From NSPs, the arabinoxylans are the most important components studied in wheat nowadays. The novelty of our study is the investigation of the variability and clustering ability of the wheat lines based on different quantitative and qualitative traits of arabinoxylans. The quantitative properties, the total and the water-extractable arabinoxylan content of wheat flours were measured separately by gas chromatography. The qualitative property referring to the structure of the molecule was the molecular weight distribution measured by size exclusion liquid chromatography. According to the results the variability of arabinoxylan properties in the breeding lines varied between wider ranges then the values measured for the parental varieties. The correlation between the quantitative parameters, and a trend between quantitative and qualitative parameters were described. During the cluster analysis, the parents were well separated into different groups. The parameters that played an important role in the clustering were the ratio of the probability of occurrence of molecular size ranges along with the quantitative traits of AX. The selected samples can be used for further targeted breeding while the methodology was used in this work can be suitable for selecting lines/varieties for special food or other industrial applications.     

不同糯小麦品种(系)品质及其烘烤制品研究

为推动糯小麦的品质改良及开发利用,以国内不同育种单位育成的多个糯小麦为试验材料,以普通强筋、中筋及弱筋小麦作为对照,分析其淀粉组分、糊化特性、面团流变学特性,并对其制作的酥条进行比较.结果表明,糯小麦的淀粉含量及直链淀粉含量显著低于普通小麦;在淀粉糊化特性上,糯小麦的低谷黏度、最终黏度、回生值显著低于普通小麦,峰值温度...     

GlutoPeak parameters of whole wheat flours for gluten quality evaluation in soft wheat breeding programs

In soft wheat breeding programs, the gluten strength of flours from specific genotypes is determined by various chemical and rheological tests. Based on such tests, the experimental wheat lines with very weak flour gluten are typically selected for the production of soft-dough biscuits, while the lines with medium gluten strength and extensibility are reserved for hard-dough biscuits. Often, the genotypes having high gluten strength are removed from such breeding programs. In the present study, the usability of the GlutoPeak tester on whole wheat flour samples was investigated for assessing the gluten strength of soft wheat breeding materials. In the study, 25 soft wheat genotypes, grown in seven locations for three years, were categorized by commonly used gluten-quality-related parameters. Based on the results of the study GlutoPeak whole wheat flour PMT values ranging from 30.0 to 50.0 s and AM values from 15.0 to 20.0 GPU were found to be suitable for soft-dough biscuit products, whereas the values between 40.0 and 60.0 s and 20.0 and 23.0 GPU were appropriate for hard-dough biscuit products. The genotypes exhibiting AM values > 24.0 GPU and PMT values > 60.0 s were judged to have too-strong gluten, and thus eliminated from the breeding program. The gluten aggregation energy (AGGEN), and the torque after the maximum torque (PM) values were only useful and applicable to flours for soft-dough products. The maximum torque (BEM) values were not effective in discriminating against the genotypes. The results of this study demonstrated that the GlutoPeak whole wheat PMT and AM parameters can be recommended as quick and accurate parameters especially for early generation screening with small-scale tests in soft wheat improvement programs.     

Thermoplastic films from wheat proteins

We show that the wheat proteins gluten, gliadin and glutenin can be compression molded into thermoplastic films with good tensile strength and water stability. Wheat gluten is inexpensive, abundantly available, derived from renewable resource and therefore widely studied for potential thermoplastic applications. However, previous reports on developing thermoplastics from wheat proteins have used high amounts of glycerol (30-40%) and low molding temperature (90-120 °C) resulting in thermoplastics with poor tensile properties and water stability making them unsuitable for most thermoplastic applications. In this research, we have developed thermoplastic films from wheat gluten, gliadin and glutenin using low glycerol concentration (15%) but high molding temperatures (100-150 °C). Our research shows that wheat protein films with good tensile strength (up to 6.7 MPa) and films that were stable in water can be obtained by choosing appropriate compression molding conditions. Among the wheat proteins, wheat gluten has high strength and elongation whereas glutenin with and without starch had high strength and modulus but relatively low elongation. Gliadin imparts good extensibility but decreased the water stability of gluten films. Gliadin films had strength of 2.2 MPa and good elongation of 46% but the films were unstable in water. Although the tensile properties of wheat protein films are inferior compared to synthetic thermoplastic films, the type of wheat proteins and compression molding conditions can be chosen to obtain wheat protein films with properties suitable for various applications.     

长江中下游麦区小麦品质改良设想

长江中下游麦区是我国唯一的弱筋小麦优势产业带,该麦区的沿江、沿海地区适宜发展弱筋小麦,其他地区适宜发展中筋小麦.弱筋、中筋小麦品种的品质遗传改良是该麦区重要育种方向之一.目前该麦区虽然育成并推广了一批弱筋、中筋小麦品种,基本满足了生产上对优质小麦品种的需求,但还存在一定的问题.如新育成的弱筋小麦品质并不优于扬麦9号和宁麦9号,中筋小麦面筋含量和强度还需提高.针对存在的问题,提出该麦区小麦品质改良的3个设想:(1)利用高分子量谷蛋白亚基缺失,降低面筋强度,培育优质弱筋小麦;(2)利用优质高分子量麦谷蛋白亚基组合,改善蛋白质组分,提高面筋强度,培育优质中筋小麦;(3)利用Wx蛋白亚基缺失,培育弱筋和中筋兼用型小麦,使该麦区小麦品种在蛋白质含量和面筋含量偏高而不能作为弱筋小麦使用时,利用其优良的淀粉品质加工品质较优的面条.     

Glu-D1d与Wx-B1b基因聚合在强筋小麦育种中的利用

Glu-D1d与Wx-B1b基因遗传效应是面包面条兼用型强筋小麦的主要遗传基础,二者聚合可实现蛋白质(面筋)质量和淀粉特性的同步改良,并拓宽和提升强筋小麦的加工用途和商品价值。本文总结了Glu-D1d与Wx-B1b基因及其聚合对强筋小麦品质的影响,并对两个基因聚合育种策略和注意事项进行探讨,以期为面包面条兼用型强筋小麦育种提供理论依据和实践经验。     

Modification of gluten by methionine binding to prepare wheat bread with reduced reactivity to serum IgA of celiac disease patients

Celiac disease (CD) is caused by ingestion of wheat gluten proteins, due to immune response to proline- and glutamine-rich sequences. In this study, for reduction of the immune recognition, gluten proteins were enzymatically modified by binding methionine to the amino lateral groups of glutamine residues. Additionally, a bread-making process with modified gluten was assayed. The methionine binding was monitored by measuring the alpha-amino group disappearance and reduction of celiac IgA immunoreactivity. The best methionine binding was after 60 min reaction at pH 10, inducing a reduced to null IgA immunoreactivity to prolamins extracted from modified gluten. The bread prepared with modified gluten had lower specific volume (3.86 cm³/g) than the control wheat bread (4.52 cm³/g) but higher than those reported for gluten-free loaves. The preserved functionality of gluten proteins will make it feasible to apply this kind of modification in different wheat-based foodstuffs like the assayed bread in this study.     

不同品质类型小麦阿拉伯木聚糖流变性质的研究

为了解阿拉伯木聚糖流变性质及其与小麦品质的关系,对不同品质类型的小麦（强筋、弱筋）阿拉伯木聚糖(简称WEAX)的零剪切黏度（η0）及酶促氧化胶凝能力等指标进行了研究。结果表明,不同品质类型小麦间WEAX溶液的黏度特性存在一定差异,零剪切黏度值（η0）变幅为0.20～56.50 Pa·s,大部分集中在0.20～2.43 Pa·s,个别品种（中优206、烟农19）数值偏差较大。在过氧化物酶体系(POX/H2O2)作用下,WEAX凝胶特性（G′、G″值）差异显著,强筋与弱筋小麦中均存在胶凝能力或强或弱的品种,说明WEAX的上述流变特性与小麦筋力（或硬度）无直接关系。     

小麦贮藏蛋白特性及其遗传转化

小麦籽粒贮藏蛋白由醇溶蛋白和谷蛋白组成。醇溶蛋白在组成上以单体形式存在 ,具有高度的异质性和复杂性。它决定小麦面筋的粘性。谷蛋白是由多个亚基组成的高分子聚合体 ,决定面筋的弹性。它可分为低分子量谷蛋白亚基和高分子量谷蛋白亚基 (HMW- GS)。HMW- GS具有相似的分子结构 ,即由中央重复序列、无重复的 N端和 C端组成。HMW- GS对小麦烘烤品质起着决定性作用 ,但因 HMW- GS类型不同而对加工品质的贡献大小各异。许多 HMW- GS基因已被揭示。实践证明 ,利用基因枪法 ,将 HMW- GS基因导入普通小麦的细胞核内 ,能够达到改良小麦烘焙品质的目的。随着分子生物学技术的不断发展 ,可望从营养和加工角度来改良小麦品质的特性     

2006-2016年河南省小麦区域试验品种（系）的品质性状分析

为了解近年来河南省小麦品种的品质现状及变化规律,对2006-2016年河南省小麦区域试验的749个参试小麦品种（系）的籽粒品质和面粉加工品质指标进行分析。结果表明,参试小麦材料的籽粒容重、蛋白质含量、湿面筋含量平均值均较高,能达到或接近强筋小麦的要求,但是稳定时间相对偏低。随年份的推移,容重、蛋白质含量和湿面筋含量平均值均呈下降趋势,硬度、吸水率、稳定时间和沉淀指数均呈上升趋势,说明河南省参试小麦品种（系）籽粒的蛋白质质量在逐渐提高。容重、硬度、蛋白质含量和湿面筋含量达到国家强筋和中强筋小麦标准的品种较多,稳定时间达到弱筋和中筋标准的品种较多,说明供试小麦品种品质结构发展不平衡。河南省2006-2016年度区试品种（系）以中筋品种为主,其次为中强筋、强筋和弱筋。因此,当前河南省小麦品质改良的重点仍是蛋白质质量的改良、各品质性状平衡协调发展。     

Improving the baking quality of bread wheat using rapid tests and genomics: The prediction of dough rheological parameters by gluten peak indices and genomic selection models

The measurement of baking quality by dough mixing and viscoelastic tests is often labor-intensive and time-consuming, thus the possibility to predict these rheological parameters either by rapid tests or genomic selection models based on molecular markers was investigated in this study. A winter wheat breeding population of 128 genotypes was measured for its rheological parameters, gluten peak indices and other rapid test variables in multiple environments. The prediction accuracy of the rheological parameters was assessed in different cross-validation schemes, reflecting scenarios encountered either in food-processing or by plant breeders. Predictions based on gluten peak indices (r = 0.41–0.82) outperformed the other investigated rapid tests in the food-processing scenario. The combination of gluten peak indices with sedimentation value and protein content gave furthermore the overall highest prediction accuracy (r = 0.70). Cross-validation results from the plant breeding scenario revealed that the prediction accuracy of genomic selection models was merely slightly lower (r = 0.42) than using a combination of sedimentation value and protein content (r = 0.44). Merging gluten peak indices with genomic estimated breeding values resulted in a higher accuracy than either method alone (r = 0.52), and was a promising strategy to select for baking quality in wheat breeding.     

Natural variation in avenin epitopes among oat varieties: Implications for celiac disease

Celiac disease (CD) is a chronic inflammatory disease affecting the small intestinal mucosa. The causative agents have been identified as gluten proteins from wheat, barley, and rye, and the only available treatment for CD patients is a lifelong gluten-free diet. Non-gluten containing cereals would be a valuable contribution to the gluten-free diet. In this respect, oats are a good choice. However, commercial lots of oat flakes and flour frequently are contaminated with wheat, barley, and rye, and two studies have reported that some peptides derived from the gluten-like avenin storage proteins of oat can trigger an immune response in some CD patients. In the present study we have initiated the investigation whether all oat varieties contain similar amounts of potentially harmful sequences by biochemical and immunological methods. We confirm that commercial oat preparations are contaminated with other cereals that contain gluten or gluten-like proteins. Moreover, our results demonstrate that contamination-free oat varieties differ in their capacity to stimulate an avenin-sensitive gamma-gliadin specific T cell line derived from a patient with CD, indicative for differences in the two known avenin epitopes among oat varieties, implying that selection and breeding of completely safe oat varieties for all CD patients may be a realistic possibility.     

Reactivity of gluten detecting monoclonal antibodies to a gliadin reference material

People affected by coeliac disease need to adhere to a life-long gluten-free diet to avoid symptoms. ELISA-tests are seen as the mainstay for the detection of gluten in gluten-free food because of their sensitivity. They can, however, yield different gluten amounts depending on the antibody and reference material used. We compared the reactivity of three prominent mouse anti-gliadin-antibodies to a reference gliadin isolated from 28 common bred European wheat varieties. The reference material proteins were labelled with fluorescent dye Cy3. They were then separated by 2DE and transferred by Western blot onto low fluorescent PVDF-membranes, followed by incubation with the three primary anti-gliadin antibodies one by one. Detection of the reacting proteins used anti-mouse antibody which was labelled with fluorescent dye Cy5. The use of this technique made it possible to co-detect the 2DE-image of the reference material proteins (Cy3) and proteins reacting with the respective antibody (Cy5). The three investigated antibodies had dissimilar reactivities with different proteins of the reference gliadin. Antibodies R5 and PN3 reacted mainly with gliadin fractions, antibody 401.21 mainly with high molecular weight glutenins. The results confirm the individual specificity of these antibodies and demonstrate the importance of validating immunochemical methods for gluten detection.     

Use of chemical redox agents and exogenous enzymes to modify the protein network during breadmaking – A review

During breadmaking, a continuous protein network is formed which confers visco-elasticity to dough. The properties of this protein network are highly dependent on the characteristics of the gluten proteins of the wheat flour. A good quality (highly elastic) gluten network retains the carbon dioxide that is produced by the yeast, giving dough and bread with optimal properties. However, the properties of the gluten proteins can differ substantially between wheat flours and are highly dependent on genetic, environmental and post-harvest conditions. Deficiencies in wheat quality for breadmaking can be overcome by incorporating exogenous components which alter the functionality of the gluten proteins during breadmaking. These include additives (e.g. potassium bromate, iodate, chlorine dioxide and chlorine, azodicarbonamide, ascorbic acid and peroxides) and enzymes affecting protein crosslinking. Transglutaminase, glucose oxidase, hexose oxidase and laccase all promote the formation of covalent bonds between gluten proteins and, hence, can serve as alternatives to chemical bread improvers.     

东北春麦区强筋小麦育种进展及产业发展分析

东北春麦区是中国强筋小麦重要生产基地之一。近年来,该麦区强筋小麦育种和产业化进展较大：创建的强筋小麦育种高效技术体系已成功运用于东北春小麦育种之中;选育推广的优质高产多抗强筋小麦新品种,使当地小麦主导（栽）品种实现了强筋化;创建的强筋小麦基因库和多赢产业化模式,为东北春麦区强筋小麦育种和产业发展提供了重要科技支撑与物质保障。本文总结了东北春麦区强筋小麦育种进展,分析了产业发展存在的问题,重点讨论了未来强筋小麦育种和产业发展的方向,并提出一些策略与建议,以期为推动东北春麦区乃至中国强筋小麦育种和产业发展提供参考。