Purification and immunoglobulin E epitopes identification of low molecular weight glutenin:an allergen in Chinese wheat

As one of the most important cereals,wheat(Triticum aestivum)has high nutritional value and is widely cultivated in China.However,wheat can cause severe allergic reactions,and a growing number of people are developing allergies to Chinese wheat.Low molecular weight glutenin(LMW-GS),an important allergen in susceptible populations,is responsible for celiac disease and wheat contacts dermatitis.In this study,LMW-GS was highly purified from Chinese wheat(Xiaoyan 6)and further identified and characterized.In addition,8 peptides were predicted efficiently by 5 immunological tools,among which 5 peptides showed significant immunoglobulin E binding abilities.Two specific epitopes were found to be in the non-conserved region of the amino acid sequence of LMW-GS,which was speculated to be the specific epitope of Chinese wheat.This systematic research of LMW-GS may provide new insights into the prevention of wheat allergy and development of hypoallergenic wheat products.

Composition and Content of High-Molecular-Weight Glutenin Subunits and Their Effects on Wheat Quality

Sedimentation values, flour glutenin macropolymer (GMP) contents, composition and contents of high-molecular-weight (HMW) glutenin subunits (GS) of 233 flour samples were determined. Our data indicated that subunit 1 occurred more frequently at Glu-A1 , subunit pair 7 + 8 at Glu-B1 and 2 + 12 at Glu-D1. The significant relationships between Glu-1 quality score and total HMW glutenin content, sedimentation value and GMP content suggested that the composition of HMW-GS affects wheat quality strongly. Moreover, the total content of HMW-GS was correlated with certain quality parameters more significantly. Relationship between subunit 5 + 10 content and breadmaking quality was better than others, but 2 + 12, 7 + 8, 7 + 9 and 4 + 12 also correlated with certain quality parameters significantly. The contents of total HMW-glutenin, x-type subunits and y-type subunits related with sedimentation value, flour GMP content, and Glu-1 quality score more strongly than that of individual subunit or subunit pair. The flour GMP content, with excellent correlation to sedimentation value, total contents of HMW glutenin, x- and y-type subunits and many other quality parameters, could be an ideal indicator of breadmaking quality at earlier generations for breeding purpose for its simple procedure and small scale.

Analysis of Dynamic Accumulation of Three Types of Glutenin Subunits and Their Content in Relation to Sedimentation Value in Common Wheat

The biosynthetic time and accumulations of A-, B-, and C-type glutenin subunits in 7 winter wheat cultivars with different quality （strong, medium, weak gluten） were analyzed by SDS-PAGE. The results showed that no glutenin subunit was observed within 8 d after anthesis. Parts or all A-, B-, and C-type subunits appeared around day 12 in different cultivars. Other A-, B-, and C-type subunits appeared gradually. The accumulation of A-, B-, and C-type subunits fluctuated before maturity. The results of analysis of correlation between the ratios of A/T （total content of glutenin subunits）, A/C, AJ （B＋C）, （A＋B）/C, and （A＋B）/T and SDS-sedimentation value suggested that they were more significant. The negative correlation between the ratio of （B＋C）/T and SDS-sedimentation value was more significant, and the correlations between the ratio C/T and the SDS-sedimentation value were significantly negative.

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

Nitrogen(N),a macronutrient essential for plant growth and development,is needed for biosynthesis of protein and starch,which affect grain yield and quality.Application of high-N fertilizer increases plant growth,grain yield,and flour quality.In this study,we performed the first comparative analysis of gliadin and glutenin subproteomes during kernel development in the elite Chinese wheat cultivar Zhongmai 175 under high-N conditions by reversed-phase ultra-performance liquid chromatography and twodimensional difference gel electrophoresis(2D-DIGE).Application of high-N fertilizer led to significant increases in gluten macropolymer content,total gliadin and glutenin content,and the accumulation of individual storage protein components.Of 126 differentially accumulated proteins(DAPs)induced by high-N conditions,24 gliadins,12 high-molecularweight glutenins,and 27 low-molecular-weight glutenins were significantly upregulated.DAPs during five kernel developmental stages displayed multiple patterns of accumulation.In particular,gliadins and glutenins showed respectively five and six accumulation patterns.The accumulation of storage proteins under high-N conditions may lead to improved dough properties and bread quality.

Study on Relationship Between the Size Distribution of Glutenin Polymeric Protein and Wheat Flour Mixing Properties

Parental varieties Suneca and Cook have contrasting alleles at each of the five glutenin subunit loci (Glu-B1, Glu-D1 Glu-A3, Glu-B3, and Glu-D3), a set of 60 lines homozygous at these loci from the F4 progeny population of Suneca X Cook was chosen to analyze the variation of the size distribution of glutenin polymeric protein (measured by SE-HPLC) and flour mixing properties of these lines and to study relationship between the size distribution of glutenin polymeric protein and wheat flour mixing properties. The results showed that there were very significant differences among the relative size distributions of glutenin polymeric protein (i.e. percentage of unextracTable polymeric protein in the total polymeric protein, or UPP%) and dough development times (i.e. peak time of mixograph, or PTM) of different homozygous lines, respectively. Flour mixograph shape was closely related to UPP% value. The results also indicated that UPP% was very strongly positive correlation with PTM and negative correlation with peak height of mixograph (PHM). Comparing with flour protein content (FP%), UPP% gave greater effect on PTM and PHM, i.e. flour mixing properties, and it can be considered as one of criteria for quality selecting from early generation of breeding program.

Allelic Variation and Genetic Diversity at HMW Glutenin Subunits Loci in Yunnan, Tibetan and Xinjiang Wheat

Allelic variation and genetic diversity at HMW glutenin subunits loci, Glu-A1, Glu-B1and Glu-D1 were investigated in 64 accessions of three unique wheats of western Chinausing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Two HMWglutenin patterns (i.e., null, 7+8, 2+12 and null, 7, 2+12) in 34 Yunnan wheataccessions, 3 HMW glutenin patterns (i.e., null, 7+8, 2+12; null, 6+8, 2+12 andnull, 7+8, 2) in 24 Tibetan accessions and 1 HMW glutenin pattern (null, 7, 2+12) in6 Xinjiang wheat accessions were found. The Tibetan accession TB18 was found to be witha rare subunit 2 encoded by Glu-D1. A total of 4 (i.e., Glu-A1c, Glu-B1a, Glu-B1b andGlu-D1a), 5 (i.e., Glu-A1c, Glu-B1d, Glu-B1b, Glu-D1a and Glu-D1) and 3 alleles (i.e.,Glu-A1c, Glu-B1a and Glu-D1a) at Glu-1 locus were identified among Yunnan, Tibetan andXinjiang unique wheat accessions, respectively. For Yunnan wheat, Tibetan wheat andXinjiang wheat, the Neis mean genetic variation indexes were 0.1574, 0.1366 and 0,respectively, which might indicate the higher genetic diversity at HMW glutenin subunitsloci of Yunnan and Tibetan wheat accessions as compared to that of Xinjiang wheataccessions. Among the three genomes of hexaploid wheats of western China, the highestNeis genetic variation index was appeared in B genome with the mean value of 0.2674,while the indexes for genomes A and D were 0 and 0.0270, respectively. It might bereasonable to indicate that Glu-B1 showed the highest, Glu-D1 the intermediate and Glu-A1 always the lowest genetic diversity.

High-Molecular-Weight Glutenin Subunit Composition of Chinese Wheat Germplasm

The objective of the present study was to characterize the high molecular glutenin subunits （HMW-GS） composition and the presence of 1B/1R translocation in newly developed wheat （Triticum aestivum L.） germplasm, which have one or more traits that are useful in wheat improvement. Sodium dodecyl sulphate polyacrylamide-gel electrophoresis （SDS-PAGE） and acid polyacrylamide-gel electrophoresis （A-PAGE） were used to detect HMW-GS composition and the presence of 1B/1R wheat-rye （Secale cereale L.） chromosome translocation in the wheat germplasm. Bread-making quality scores of these lines were determined. A high level of variations in HMW-GS encoded by Glu-1 locus was observed. Sixteen major HMW-GS, with 30 combinations, were detected. The percentage of cultivars with more than two desirable subunits was 38.7%. Thirteen cultivars had bread-making quality scores of 10 in combination with one or two desirable agronomical traits, such as high-yield potential, dwarfing stem, resistance to diseases, and/or tolerance to abiotic stress. Sixty-eight （36.6%） cultivars possessed 1B/1R translocation. The newly developed germplasm with HMW-GS for good quality can be promising resources for improving bread-making quality of wheat.

Swelling Index of Glutenin (SIG) Related to Protein Quality, DoughCharacters and Noodle Quality

The swelling index of glutenin (SIG) and the protein fraction of 25 Chinese wheat varieties were studied with new protein fractions extracting method. The protein fractions compose of monomeric protein, soluble glutenin and insoluble glutenin. The relations between other protein index, dough character, and fresh noodle quality were also discussed. The SIG results at different time is positively and highly significantly related to the insoluble glutenin content (r= 0.808 -0.867, P< 0.01). The SIG result can reflect the insoluble glutenin content. The protein content, gluten index, farinograph stability time, extensibility length and extensigram energy were positively and significantly correlated with SIG5 and SIG20 (r= 0.516 - 0.734, P<0.05, 0.01).SIG proved to be applicable in Chinese wheat dough evaluation. Fresh noodle making quality parameters were evaluated by fresh noodle length, thickness, maximum resistance to extension, extension area and extension distance, while cooked noodle texture was determined by cutting firmness, compression recovery, surface firmness and TPA by using a texture analyzer of TA.XT2i. The noodle cooking quality was significantly correlated with SIG value. The surface firmness and cutting firmness were more desirable for predicating the quality difference than TPA test and compression. Cooking loss and water absorption were negatively related to SIG value and insoluble content (r = -0.556 - - 0.787, P < 0.05, 0.01). The results showed that SIG test was also suitable in evaluating noodle making and cooking quality in very small sample size, which was very important in wheat breeding programs. Therefore, SIG test, as a small scale test, is suitable to evaluate dough rheological properties for Chinese wheat varieties, and will be helpful in cereal research and wheat breeding program, especially, in early generations.

Smart Colorimetric Corn Starch Films Combined with Anthocyanin-Loaded Glutenin-Carboxymethyl Chitosan Nanocomplexes for Freshness Monitoring of Chilled Pork

In this study,intelligent,pH-responsive colorimetric films were prepared by encapsulating anthocyanins in nanocomplexes prepared from glutenin and carboxymethyl chitosan.These nanocomplexes were added to a corn starch matrix and used in the freshness monitoring of chilled pork.The effects of anthocyanin-loaded nanocomplexes on the physical,structural,and functional characteristics of the films were investigated.The addition of anthocyanin-loaded nanocomplexes increased the tensile strength,elongation at break,hydrophobicity,and light transmittance of the films while decreasing their water vapor permeability.This is because new hydrogen bonds are formed between the film components,resulting in a more homogeneous and dense structure.The colorimetric film has a significant color response to pH changes.These films were used in experiments on the freshness of chilled pork,in which the pH changes with changing freshness states.The results show that the colorimetric film can monitor changes in the freshness of chilled pork in real time,where orange,pink,and green represent the fresh,secondary fresh,and putrefied states of pork,respectively.Therefore,the intelligent colorimetric film developed in this study has good application potential in the food industry.

Cloning and Expression of Low Molecular Weight Glutenin Genes from the Chinese Elite Wheat Cultivar ＂Xiaoyan 54＂

The low molecular weight （LMW） glutenln subunlts account for 40% of wheat gluten protein content by mass and these proteins are considered to significantly affect dough quality characteristics. Five new full-length LMW glutenln genes （designated LMW-5, LMW-7, LMW-42, LMW-58, and LMW-34） were isolated from the Chinese elite wheat cultivar ＂Xlaoyan 54＂ by PCR amplification of genomlc DNA using a pair of degenerate primers designed from the conserved sequences of the N- and C-terminal regions of published LMW glutenln genes. Deduced amino acid sequence analysis showed that LMW-5 belongs to the LMW-i type genes and that the other four belong to LMW-m type genes. Sequence comparisons revealed that point mutations occasionally occurred in signal peptide and N-terminus domains and often existed in domain III and domain V. Small insertions and deletions are represented in the repetitive domain. There is a stop codon after amino acid position 110 In the repetitive domain of LMW.34, indicating that It is a pseudogene. The other four genes have complete open reading frames and the putative mature regions of these genes were subcloned Into pET-30a expression vector and successfully expressed in Escherlchla coll. Protein sodium dodecyl sulfate-polyacrylamlde gel electro- phoresls analysis showed that all proteins expressed in E. coil by the four genes could be related to B-group LMW glutenln subunits of wheat.

7^(OE)+8^(*)亚基对东北强筋小麦品种品质性状影响研究

小麦品质改良是东北春麦区强筋小麦育种的主要目标之一。Glu-B1位点7^(OE)+8^(*)亚基为超强筋小麦品种必备基因。为了明确该亚基在东北春麦区强筋小麦遗传背景下的品质遗传效应,本研究利用分子标记和选择回交相结合的手段,将7^(OE)+8^(*)亚基定向导入到强筋小麦品种龙麦26和龙麦35(Glu-B1位点均为7+9亚基)的遗传背景之中,对BC5F1、BC6F1群体和自交BC6F2鉴定获得的纯合品系进行7^(OE)+8^(*)亚基遗传效应评价。结果表明,在强筋小麦品种龙麦26(7+9)和龙麦35(7+9)遗传背景下转入7^(OE)+8^(*)亚基后,其干面筋、面筋指数、形成时间、稳定时间、断裂时间、拉伸面积、延伸性和最大抗延阻力等品质指标3年平均分别提高1.3%(P=0.82)和1.8%(P=0.49)、6.6%(P=0.59)和4.7%(P=0.37)、55.0%(P=0.24)和35.8%(P=0.56)、44.5%(P=0.43)和32.8%(P=0.73)、41.4%(P=0.31)和30.0%(P=0.66)、28.0%(P=0.05)和23.4%(P=0.37)、6.5%(P=0.47)和5.8%(P=0.42)、19.5%(P=0.31)和18.0%(P=0.38);Zeleny沉降值2年平均分别提高6.8%和11.4%。以上结果表明,在2个强筋小麦品种遗传背景下,Glu-B1位点转入7^(OE)+8^(*)亚基较7+9亚基对各项品质指标改良均存在正向效应,但提高幅度存在差异,对形成时间、稳定时间、断裂时间、最大抗延阻力、拉伸面积等衡量面筋质量的指标提高幅度更大,表明该亚基对面筋质量改良效应显著。综上所述,7^(OE)+8^(*)亚基可作为东北春麦区强筋小麦遗传背景下品质性状进一步改良的优选基因,为超强筋小麦育种的重要基因资源。

引进美国小麦种质资源抗病性及品质性状鉴定

为了挖掘新的种质资源,本研究对引自美国的442份小麦材料对白粉病和条锈病的抗病性、蛋白含量以及高分子量麦谷蛋白(HMW-GS)亚基组成进行了鉴定分析。抗病性鉴定结果显示,153份材料抗白粉病,27份抗条锈病,6份兼抗两种病害。蛋白质含量达到GB/T 17892-1999《优质小麦强筋小麦》一等(粗蛋白质含量≥15.0%)的样品有143份。高分子量麦谷蛋白检测发现,供试材料共含18种HMW-GS亚基和100种不同亚基组合类型,其中N,7+9,5+10出现次数最多,优质亚基1、2*、7^(oe)、17+18、5+10的材料分别占总材料数的25.6%、5.2%、27.8%、7.7%和25.6%,含7^(oe),5+10亚基的有36份,含2*,5+10亚基的有1份,含2*,7^(oe)亚基的有7份。综合抗病性及品质分析结果显示,PI 17738等11份材料至少抗1种病害,且蛋白含量≥15.0%,湿面筋含量≥35.0%,同时含有稀有优质亚基。以上11份材料可作为我国优质、抗病小麦培育亲本,为我国小麦抗病和品质遗传改良提供优异基因源。

甘肃冬小麦品种(系)面粉品质性状相关基因分析

为了解甘肃省近20年育成的106份冬小麦品种(系)中加工品质性状相关基因分布情况,用22个分子标记对供试材料的HMW-GS、LMW-GS、面粉色泽及籽粒硬度等品质性状相关基因进行了分析。结果发现,供试品种(系)的HMW-GS相关基因中,在Glu-A1位点检测到34份品种(系)含有AxNull,频率为32.08%;在Glu-B1位点检测到Bx7+By8和Bx14+By15共2种基因组合,分别占17.92%和25.47%;在Glu-D1位点检测到11份品种(系)含有Dx5+Dy10,占10.38%。对LMW-GS鉴定结果显示,29份品种(系)含Glu-A3d基因,分布频率为27.36%。HMW-GS和LMW-GS亚基组合中,含有4个、3个和2个位点优质亚基基因组合的品种(系)分别占0.94%、8.49%和3.77%。对面粉色泽相关基因Ppo-A1、Ppo-D1、Psy-A1、Lox-B1和TaPod-A1位点的检测发现,优异等位变异占比分别为39.62%、50.94%、31.13%、30.19%和38.68%。对籽粒硬度相关基因检测发现,在Pina、Pinb和Pinb-2等位变异位点的检测到6种基因型,分别为Pina-D1a、Pina-D1b、Pinb-D1a、Pinb-D1b、Pinb-2v2和Pinb-2v3,分别占比90.57%、9.43%、41.51%、58.49%、14.15%和85.85%。综上所述,甘肃省近20年育成的小麦品种(系)中,麦谷蛋白亚基、籽粒硬度和面粉色泽相关基因组成丰富,但品质性状相关优质基因出现频率低且聚合多位点优势基因品种(系)少,品质改良工作亟需进一步加强。

Identification of a novel HMW glutenin subunit and comparison of its amino acid sequence with those of homologous subunits

Aegilops tauschii is the donor of the D genome of common wheat (Triticum aestivum). Genetic variation of HMW glutenin subunits encoded by the Glu-1Dt locus of Ae. tauschii has been found to be higher than that specified by the Glu-1D locus in common wheat. In the present note, we report the identification of a novel HMW glutenin subunit, Dy13t, from Ae. tauschii. The newly identified subunit pos-sessed an electrophoretic mobility that was faster than that of the Dy12 subunit of common wheat. The complete ORF of encoding the Dy13t subunit contained 624 codons (excluding the stop codons). The amino acid sequence deduced from the Dy13t gene ORF was the shortest among those of the previ-ously reported subunits derived by the D genome. A further comparison of Dy13t amino acid sequence with those of the subunits characterized from the A, B, D, R genomes of Triticeae showed that the smaller size of the Dy13t subunit was associated with a reduction in the size of its repetitive domain.

HMW glutenin subunits in multiploid Aegilops species: composition analysis and molecular cloning of coding sequences

The Aegilops genus contains species closely related to wheat. In common with wheat, Aegilops species accumulate high molecular weight (HMW) glutenin subunits in their endospermic tissue. In this study, we investigated the composition of HMW glutenin subunits in four multiploid Aegilops species using SDS-PAGE analysis. Furthermore, by working with Ae. ventricosa, we established an efficient ge-nomic PCR condition for simultaneous amplification of DNA sequences coding for either x- or y-type HMW glutenin sub-units from polyploid Aegilops species. Using the genomic PCR condition, we amplified and subsequently cloned two DNA fragments that may code for HMW glutenin subunits in Ae. ventricosa. Based on an analysis of the deduced amino acid sequences, we concluded that the two cloned sequences encode one x- and one y-type of HMW glutenin subunit, respectively.

Isolation and Molecular Characterization of High Molecular Weight Glutenin Subunit Genes 1Bx13 and 1By16 from Hexaploid Wheat

The high molecular weight glutenin subunit （HMW-GS） pair 1Bx13＋1By16 are recognized to positively correlate with bread-making quality; however, their molecular data remain unknown. In order to reveal the mechanism by which 1By16 and 1Bx13 creates high quality, their open reading frames （ORFs） were amplified from common wheat Atlas66 and Jimai 20 using primers that were designed based on published sequences of HMW glutenin genes. The ORF of 1By16 was 2220bp, deduced into 738 amino acid residues with seven cysteines including 59 hexapeptides and 22 nanopeptides motifs. The ORF of 1Bx13 was 2385bp, deduced into 795 amino acid residues with four cysteines including 68 hexapeptides, 25 nanopeptides and six tripepUdes motifs. We found that 1By16 was the largest y-type HMW glutenin gene described to date in common wheat. The 1By16 had 36 amino acid residues inserted in the central repetitive domain compared with 1By15. Expression in bacteria and western-blot tests confirmed that the sequence cloned was the ORF of HMW-GS 1By16, and that 1Bx13 was one of the largest 1Bx genes that have been described so far in common wheat, exhibiting a hexapeptide （PGQGQQ） insertion in the end of central repetitive domain compared with 1Bx7. A phylogenetic tree based on the deduced full-length amino acid sequence alignment of the published HMW-GS genes showed that the 1By16 was clustered with Glu-1B-2, and that the 1Bx13 was clustered with Glu-1B-1 alleles.

核桃谷蛋白抗菌肽的分离纯化及抑菌稳定性分析

目的:以核桃粕谷蛋白为原料生产抗菌肽,研发一种新型抗生素的替代品。方法:通过菌酶协同固态发酵法(枯草芽孢杆菌和碱性蛋白酶协同)从核桃粕谷蛋白中制备抗菌肽,通过超滤、凝胶层析过滤、液相色谱-串联质谱(liquid chromatography-tandem mass spectrometry,LC-MS/MS)和分子对接对核桃粕谷蛋白抗菌肽(walnut glutelin antimicrobialpeptide,WGP)进行分离、纯化和筛选。以对大肠杆菌和金黄色葡萄球菌的抑菌性保持率为指标,研究抗菌肽的抑菌稳定性。结果:经超滤、凝胶层析分离后,WGP-ⅢA和WGP-ⅢC组分均具有较强抗菌活性;LC-MS/MS结合虚拟筛选,从2种组分中共鉴定得到6条多肽,分子对接筛选得到3个肽段,分别为WGP-ⅢA组分的LAEAYNIPDTIARRL和WGP-ⅢC组分的SHSVIYVIR、APQLLYIVK;分子对接结果显示,WGP-ⅢC组分的抑菌活性更强;抑菌稳定性分析表明,核桃谷蛋白抗菌肽在高温热处理、紫外线、不同pH值下和不同蛋白酶处理后均表现出较好的稳定性。结论:核桃粕谷蛋白抗菌肽在食品抑菌防腐领域具有一定的应用价值。

Genetic Analysis of Chromosomal Loci Affecting the Content of Insoluble Glutenin in Common Wheat

In common wheat, insoluble glutenin （IG） is an important fraction of flour glutenin macropolymers, and insoluble glutenin content （IGC） is positively associated with key end-use quality parameters. Here, we present a genetic analysis of the chromosomal loci affecting IGC with the data collected from 90 common wheat varieties cultivated in four environments. Statistical analysis showed that IGC was controlled mainly genetically and influenced by the environment. Among the major genetic components known to affect end-use quality, 1BL/1RS translocation had a significantly negative effect on IGC across all four environments. As to the different alleles of Glu-A1, -B1 and -D1 loci, Glu-Ala, Glu-Blb and Glu-Dld exhibited relatively strong positive effects on IGC in all environments. To identify new loci affecting IGC, association mapping with 1355 DArT markers was conducted. A total of 133 markers were found associated with IGC in two or more environments （P 〈 0.05）, ten of which consistently affected IGC in all four environments. The phenotypic variance explained by the ten markers varied from 4.66% to 8.03%, and their elite alleles performed significantly better than the inferior counterparts in enhancing IGC. Among the ten markers, wPt-3743 and wPt-733835 reflected the action of Glu-D1, and wPt-664972 probably indicated the effect of GIu-A1. The other seven markers, forming three clusters on 2AL. 3BL or 7BL chromosome arms, represented newly identified genetic determinants of IGC. Our work provided novel insights into the genetic control of IGC, which may facilitate wheat end- use quality improvement through molecular breeding in the future.

优质强筋春小麦种质筛选及高分子量谷蛋白序列分析

小麦是重要的口粮作物,加工品质的遗传改良是小麦育种的重要目标之一。为了丰富小麦加工品质育种的基因资源,本研究在收集的种质资源中筛选出农艺性状优良的SG-1、SG-2和SG-3,并对其进行加工品质分析和籽粒储藏蛋白组成分析,并评估它们在育种上的利用价值和方式,使用SDS-PAGE、A-PAGE、高分子量谷蛋白亚基编码基因测序、SDS沉降值分析等技术,对这些小麦品种的籽粒储藏蛋白亚基组成进行分析。研究发现,SG-1携带非优质的高分子量谷蛋白亚基Dx2+Dy12,而SG-2和SG-3携带优质的高分子量谷蛋白亚基Dx5+Dy10。在醇溶蛋白方面,3份资源都检测到了γ-1型醇溶蛋白,但只有SG-3检测到了γ-2型醇溶蛋白。加工品质分析显示,SG-1的加工品质优于天津推广的优质强筋春小麦品种津强6号。高分子量谷蛋白亚基序列分析发现,SG-1和SG-3在By8亚基存在序列变异,表明尽管它们在SDS-PAGE水平上亚基类型一致,但在DNA序列上仍然存在变异。本研究结果初步解释了携带优质亚基的小麦品种在加工品质上表现不佳的原因可能是DNA序列存在差异。同时,研究人员还发现携带非优质亚基但具有优良加工品质的SG-1,说明SG-1可能存在其他能够提升小麦加工品质的机制。本研究拓宽了小麦加工品质育种的基因资源,并为加工品质形成机制的解析提供了新的资源和理论依据。

菌酶协同固态发酵核桃谷蛋白制备抑菌肽

核桃粕作为榨油副产物常被用作饲料或丢弃,造成大量优质蛋白资源的浪费。本文为高值化利用核桃粕资源,以其中含量最高的谷蛋白为原料,采用枯草芽孢杆菌和碱性蛋白酶协同固态发酵法制备核桃谷蛋白抑菌肽。以多肽含量和抑菌圈直径作为评价指标,进行单因素实验和响应面试验优化最佳菌酶协同固态发酵工艺参数。对制备的谷蛋白抑菌肽热稳定性进行探究。结果显示,单因素实验表明谷蛋白抑菌肽对大肠杆菌和金黄色葡萄球菌均有一定的抑制作用。响应面试验下最佳发酵工艺参数为:接种量5%,料液比1:1.5,发酵温度43℃,发酵时间3 d,加酶量400 U/g。最佳工艺条件下多肽含量达到26.35±1.29 mg/g,对金黄色葡萄球菌抑菌圈直径为15.50±1.53 mm。通过差示扫描量热仪(Differential Scanning Calorimeter,DSC)分析可得,谷蛋白抑菌肽比谷蛋白具有更高的热稳定性。研究表明通过菌酶协同固态发酵核桃谷蛋白制备的抑菌肽具有良好的抑菌效果且结构相对稳定。