小麦高分子量麦谷蛋白亚基遗传变异及其与品质和其它农艺性状关系的研究

本研究应用SDS-PAGE技术分析了国内外757份供试材料的高分子量（HMW）麦谷蛋白亚基组成。共发现65种HMW亚基组成，其中53种为常见型，12种为罕见型。国外品种的亚基组合数多于国内品种，国内育成品种又多于国内地方品种。作者还发现了部分罕见亚基，即由Glu-D1编码的亚基2.2+12，2+10，2，12以及前人未曾发现的3个亚基。研究     

副猪嗜血杆菌CDT亚基原核表达及其抗原性鉴定

为原核表达副猪嗜血杆菌(H.parasuis)CDT毒素并检测其在体外培养时的分泌表达情况,本实验将切除信号肽的CDT毒素的3个亚基基因分别克隆于pET-28a载体中在大肠杆菌进行表达,并将重组蛋白经亲和层析纯化后,免疫兔制备抗血清,用于鉴定H.parasuis体外培养时CDT分泌表达情况。结果表明CDT毒素3个亚基均在Rosetta菌株中得到表达,其中cdtB约为28.2 ku,符合预期大小,而cdtA和cdtC亚基比预期的23.5 ku和17.4 ku略大。表达的3个重组蛋白可以被自然感染猪血清识别,表明其具有良好的反应原性,同时也表明H.parasuis在猪体内定殖或感染过程中分泌CDT。制备的抗血清可以与体外培养H.parasuis的分泌蛋白中的CDT亚基反应,表明重组蛋白具有良好的免疫原性,同时也表明H.parasuis体外培养时也分泌CDT。     

Changes in bread-making quality attributes of bread wheat varieties cultivated in Spain during the 20th century

Genetic gains in quality traits were assessed in grain samples from 4 field experiments involving 16 bread wheat varieties representative of those most widely cultivated in Spain during the 20th century. The allelic composition at three glutenin loci (Glu-A1, Glu-B1, and Glu-D1) was obtained by PCR-based DNA markers and published references. From 1930 to 2000 grain protein content decreased by −0.030% y⁻¹, or in relative terms by −0.21% y⁻¹, but the protein produced per hectare increased by 0.39% y⁻¹. Alveographic tests revealed significant changes in dough rheological properties. Dough strength (W) and tenacity (P) increased at relative rates of 1.38% y⁻¹ and 0.99% y⁻¹, respectively, while dough extensibility (L) decreased by −0.46% y⁻¹, resulting in an increase of 1.45% y⁻¹in dough equilibrium (P/L). The rise in protein quality could be related to the replacement of the null allele by subunits 1 or 2* at Glu-A1 and the prevalence of subunits 7 + 8 and 5 + 10 at Glu-B1 and Glu-D1 loci, respectively, in the most recent varieties. Dough extensibility was affected by water input during the crop cycle, this relationship being partially explained by the presence of the 5 + 10 HMW glutenin subunit. Fermentation tolerance was improved in the most modern varieties. Collapse during fermentation was avoided only in doughs with a W ≥ 159 J × 10⁻⁴ and a P/L ≥ 0.56 mm H₂O mm⁻¹, levels achieved by most of the modern varieties. The over-strong and unbalanced rheological properties of some modern varieties resulted in highly porous doughs, and no clear advances in dough maximum height during fermentation were attained.     

野生二粒小麦HMW-GS特异性及其对小麦的可利用性研究

对来自以色列的133份野生二粒小麦进行SDS-PAGE检测发现,其高分子谷蛋白亚基具有较高的遗传多样性。在Glu-A1和Glu-B1两个位点共有18种可确定的亚基变异类型,其中,A位点上的亚基1、2和B位点上的亚基7+8与17+18品质评分为3分(出现频率分别为59.4%和12.78%)。同时,出现了在普通小麦中不表达的1Ay亚基和许多普通小麦所稀有或缺乏的特异亚基类型,如1、7+9、17+18、7+8、7+8、7+9、7+8等,而且在22份材料中出现了9种未命名的新亚基类型。比较研究表明,高分子谷蛋白亚基的表达与材料的来源地有关。用具有1Ay亚基的材料与栽培小麦“川农16”杂交,在分离世代F2中检测到了1Ay亚基的存在。据此认为,可望将野生二粒小麦中诸如1Ay的特异高分子量谷蛋白亚基导入栽培小麦,这对拓宽小麦品质遗传基础,改良小麦加工品质具有重要意义。     

小麦远缘杂交后代的高分子量麦谷蛋白亚基组成分析

以P7和郑州9023远缘杂交F2代株系为试材,用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium do-decyl sulphate-polyacrylamide gel electrophoresis,SDS-PAGE)法鉴定分析了杂交后代的高分子量麦谷蛋白亚基(high-molecular-weight subunits of glutenin)组成。结果表明在Glu-A1,Glu-B1和Glu-D1三个位点上分别检测到2,5和2种亚基类型,3位点结合共出现10种组合类型。其中,在Glu-A1位点上出现了1和N亚基,1优质亚基出现的频率为37.5%;在Glu-B1位点上,7 8优质亚基和7 9亚基出现频率最高(均为31.3%);Glu-D1位点上出现了2 12亚基和被世界公认的优质亚基5 10,其中,5 10亚基出现频率高达68.8%。杂交后代中品质评分高达8分及以上的株系占3/8。     

Evidence for the Non-Glycoprotein Nature of High Molecular Weight Glutenin Subunits of Wheat

An isolation and purification procedure for wheat high molecular weight glutenin subunits (HMW-GS) involving no steps expected to cause deglycosylation of glycoproteins was developed to allow removal of the maximum amount of carbohydrates not covalently linked to HMW-GS. Flour was defatted and then extracted with 50%n-propanol (50%n-PrOH) to remove arabinogalactans and glucose-containing material. HMW-GS were extracted with 50%n-PrOH containing 5% β-mercaptoethanol, precipitated in 60%n-PrOH, alkylated and recovered by precipitation. The partially purified HMW-GS were separated by cation exchange chromatography and resulting fractions purified by RP–HPLC. The purified HMW-GS contained only 0·1% of glucose (corresponding to 51–59 monosaccharide residues per 100 HMW-GS molecules) and no other amino or neutral sugars. The HMW-GS gave a positive reaction in a periodate–digoxigenin glycan detection assay when labelled in solution (with or without periodate oxidation) but not when labelled directly on-the-blot. HMW-GS expressed inEscherichia coli, a micro-organism without glycosylation capabilities, reacted in an identical way. Possible reasons are given for the difference in results obtained after labelling in solution or on-the-blot. No positive reaction between the purified HMW-GS and mannose-specificGalanthus nivalisagglutinin was observed. The presence of N-acetylglucosamine in HMW-GS has been previously reported²⁰. Since neither mannose nor N-acetylgalactosamine were found in the HMW-GS, and these proteins lack the sequon necessary for N-glycosylation, only O-linked GlcNAc moieties are possible. This modification could not be detected using a galactosyltransferase labelling assay. Taken together these results suggest that HMW-GS are not glycosylated.     

对小麦不同HMW麦谷蛋白亚基质量评分系统的评价

小麦HMW麦谷蛋白亚基组成不同是造成各品种间烘烤品质差异的主要原因。不同研究者分别依据亚基间沉淀值（Payne等，1987）、评价值（傅宾孝等．1989）、抗延伸力（赵友梅等，1990）以及包括沉淀值在内的多个性状（赵和等，1994）的差异。先后建立了各自的评分系统。比较研究结果表明，前3种亚基评分系统对亚基的质量评分具有一定的共性，个别亚基的评分则存在差异；赵和等（1994）的评分系统则侧重考虑1D控制的亚基对烘烤品质的决定性作用，1A和1B控制的亚基作用甚小，因而与其余3种评分方法存在较大分歧。相关分析结果表明，就评价中国小麦品种的品质而言，国内制订的评分系统优于国外的。除容重、灰分等性状外，HMW麦谷蛋白亚基组成与大多数品质性状呈显著或极显著相关关系．     

小麦谷蛋白亚基及其基因多态性研究进展

本文主要介绍了小麦高、低分子量谷蛋白亚基及其控制基因的研究进展情况,包括各种不同的研究技术以及相应的研究结果。除了传统的SDS-PAGE技术以外,分子标记技术以及免疫化学技术都在该领域中得到日益广泛的应用,并取得了关于亚基及基因的多态性和快速鉴别方法等一系列重要的研究进展。     

小麦2+12和5+10亚基近等基因系间面粉品质差异的研究

分析和研究了小麦栽培品种克旱九、垦大四和龙麦20的高分子量麦谷蛋白亚基(HMW-GS)近等基因系的面粉品质. 这些近等基因系是通过5～6次连续的选择性回交获得的. 结果表明, 在蛋白质和干面筋含量上, 近等基因系间的差别不显著. 在湿面筋与干面筋的比值(湿面筋/干面筋)上5+10亚基的近等基因系比带有2+12亚基的近等基因系要小4.7