磷素对不同大豆品种7S和11S球蛋白亚基组成及含量的影响

【目的】研究不同磷素水平对不同大豆品种7S和11S球蛋白亚基组成及含量的影响。【方法】选用东农42（高蛋白品种）、合丰25（中间型品种）、东农46（高油品种）3个大豆品种作为试验材料,采用盆栽,在每千克土壤施N和K2O各为0.033 g基础上,设P1、P2、P3、P4 4个P处理（即每千克土壤分别施P2O5 0、0.033、0.067、0.100 g）,采用SDS-PAGE电泳法测定7S和11S球蛋白亚基组成和含量。【结果】3个大豆品种7S球蛋白由α′、α、γ、β4个亚基组成,11S球蛋白由酸性亚基和碱性亚基组成;各种亚基分子量在品种间差异不显著。同一品种不同处理间东农42和合丰25两个品种7S、11S球蛋白和各种亚基含量P3处理最高,东农46 P2处理最高;同一处理不同品种间7S、11S球蛋白和各种亚基含量始终是东农42最高,东农46最低,合丰25处于二者之间;3个大豆品种7S和11S球蛋白及各种亚基含量在品种间和施磷处理间差异显著。【结论】施磷对3个大豆品种7S和11S球蛋白各种亚基组成没有影响,对分子量影响很小。施磷对3个大豆品种7S和11S球蛋白和亚基含量有影响,适宜的施磷量有利于提高球蛋白和亚基的含量。     

Influence of gliadin removal on strain hardening of hydrated wheat gluten during equibiaxial extensional deformation

The aim of the present work has been to study the equibiaxial extensional deformation of doughs of gluten- and glutenin-rich fractions containing 40 wt% water subjected to lubricated squeezing flow with four different crosshead speeds at room temperature. The gluten dough shows strain softening and hardening in succession whilst the dough where the gliadins have been removed by alcohol extraction does not show strain hardening behavior but breaks immediately after strain softening. The equibiaxial extensional viscosity decreases with increasing strain rate at given strains, appearing as strain rate thinning behavior, which is stronger in the glutenin dough than in the gluten dough. The large extensibility with strain hardening in the gluten dough is due to the presence of gliadins acting as both plasticizers and promoters for the more extensible networks.     

Composition of polymeric proteins and bread-making quality of wheat lines with allelic HMW-GS differing in number of cysteines

Three lines of Australian wheat variety Avocet, two biotypes of Australian variety Halberd, and the Italian bread wheat cultivar Fiorello and its derived line were used to study the possible role of the Glu-B1 HMW-GS in polymeric protein composition and flour functionality. These sets of lines contain HMW-GS 7+8, 7+9, 20x+20y or 26+27. Subunit Bx7 has four cysteine residues, while subunit Bx20 has only two. Compared to Avocet A (7+8), line Avocet C (20x+20y) exhibited an increase in polymeric protein, a decrease in the gliadin-to-glutenin ratio, and a marked decrease in unextractable polymeric protein (UPP). Avocet C doughs exhibited greater extensibility and shorter Mixograph dough development times, and baked into smaller loaves compared to those from Avocet A. Similar differences were observed in comparisons between the two Fiorello lines and between the two Halberd biotypes that had differing Glu-B1 alleles. These results show that in closely related genotypes, the presence of the Bx7+By8 or Bx7+By9 HMW-GS instead of Bx20+By20 or Bx26+By27 is associated with higher UPP, higher dough strength and better bread-making performance. It is suggested that this could be due to the greater number of cysteines in the Bx7 subunit that are available for forming higher-molecular-weight glutenin polymer. This could give the possibility to manipulate dough properties and bread-making quality by utilizing HMW-GS alleles with varying numbers of cysteine residues.     

Comparison of small-scale and large-scale mixing characteristics: Correlations between small-scale and large-scale mixing and extensional characteristics of wheat flour dough

Mixing measurements provide valuable information about dough strength and stability (STAB) traits. These measurements are important in milling and baking operations, and for varietal selection in wheat breeding programmes. There are several techniques with different sample sizes used for measuring these traits so there is interest in examining the agreement between methods in terms of genotypic (varietal) rankings. This issue has been investigated by using two different mixing methods, a small-scale Mixograph (2 g) and large-scale Farinograph (50 g) using data from a doubled haploid population (190 lines) from a Chara (excellent dough strength)×WW2449 (poor dough strength) cross. The cross was grown in a field trial at the Wagga Wagga Agricultural Institute (WWAI) in 2000. Eleven mixing traits were measured and compared according to a statistical design. The estimated genetic correlation matrix for six of the 11 mixing traits, dough development time (DDT), STAB, mixing tolerance index (MTI), maximum bandwidth (MBW), bandwidth at peak resistance (BWPR) and peak resistance (PR) revealed that for these dough-strength-related parameters, both methods were measuring equivalent traits, although individual parameters had widely different coefficients of variation. In this population, PR was correlated with the extensibility trait length determined by large-scale extension testing. None of the large-scale or small-scale mixing traits was an effective predictor of the small-scale extensibility parameter extensibility at Rmax (Ext_Rmax). The data verified that small-scale Mixograph tests are a robust and efficient alternative to large-scale Farinograph tests for both commercial breeding and research.     

Relation between susceptibility to wheat bug attack and digestibility of glutenin

Two trials of winter wheat, embracing 17 varieties and 4 breeding lines, harvested in 2003 from locations in the semi-arid eastern part of Austria, were severely infested by naturally occurring bugs (Eurygaster sp.). In these trials bug damage was determined by selecting and weighing the infested kernels. Glutenin degradation was determined by the addition of meal from bug-infested kernels to meal from sound kernels from the same trials to reach sample mixtures representing a degree of bug attack of 6%. These mixtures and blanks made from sound meal were incubated in buffer solution (pH=8.5) at 37 °C for 45 min. The reduction in glutenin content due to the activity of bug proteinases was measured by RP-HPLC analysis of the glutenin fraction and comparison of the results of damaged and sound samples. The results showed good correlations between the degree of bug attack and the digestibility of glutenin (location 1: R²=0.69, P<0.01; location 2: R²=0.36, P<0.01). Both parameters seem to be variety specific. The determination of digestibility of glutenins was repeated in material from a trial harvested in 2005 in another location in eastern Austria, with eight varieties being the same as used in the 2003 trials. A correlation with the degree of bug attack in location 1 from the 2003 harvest was found again (R²=0.61, P<0.01).     

花药培养与麦谷蛋白亚基分子标记结合选育小麦新品种的研究

为快速获得携带麦谷蛋白优质亚基基因的小麦新品种,提高小麦的品质育种技术水平,利用引进的矮败材料与和尚头、甘春20号、临麦34号等10个不同品种(系)杂交,并对杂交后代进行了花药培养,获得了115份花培株系;利用PCR对花培后代株系及杂交亲本进行了优质贮藏蛋白亚基分子标记检测,3个HMW-GS为 Bx7、 Bx14、 Dx5,3个LMW-GS为 Glu-A3ac、 Glu-A3d、 Glu-B3b。结果表明,在115份花培材料中, Bx7的出现频率最高,为94.78%,其余依次为 Glu-A3ac、 Dx5、 Bx14、 Glu-A3d和 Glu-B3b;获得了44份聚合4个亚基以上的材料;结合农艺性状鉴定,筛选出了3份综合性状优异的小麦新品系AB158、AB167和AB332。本研究将花培育种技术、分子标记辅助选择技术及矮败小麦育种技术进行了有机结合,其结果可为提升小麦品质育种技术水平提供参考。     

Partitioning of glutenin flour of special wheat using aqueous two-phase systems

The partitioning behavior of the glutenin proteins was evaluated in aqueous two-phase systems (ATPSs) formed by sulfate salts (lithium or sodium) and poly(ethylene glycol) (PEG) with average molar mass of 1500 g mol⁻¹ or 4000 g mol⁻¹. The partition coefficients for the glutenin proteins in each ATPS were investigated as a function of the temperature (278.2 K–318.2 K), tie line length (TLL) and electrolyte nature. In all ATPS, the majority of glutenin proteins spontaneously concentrate in the polymer-rich phase (K_p > 1). The partition coefficient is very dependent on the salt nature and the ATPS formed by PEG + lithium sulfate presents higher K_p values as compared with the ATPS formed PEG + sodium sulfate. An increase of molar mass of polymer promotes a decrease of K_p. Thermodynamic parameters of transfer (Δ_trG, Δ_trH and Δ_trS) were obtained by the application of the Van’t Hoff equation (VHE). The values obtained by VHE indicate that the transfer of glutenin proteins to the polymer-rich phase has an enthalpic origin.     

从小麦谷蛋白大聚合体与HMW GS的关系

为了探索小麦谷蛋白大聚合体对小麦品质的影响,采用SDSPAGE方法,分析了166个来自不同地区的小麦品种高分子量谷蛋白亚基（HMWGS）的组成,并对不同亚基与小麦谷蛋白大聚合体（GMP）的关系进行了分析。结果表明,所用小麦材料HMWGS的变异类型丰富,但亚基组合仍以N/7+9/2+12为主。HMWGS对面粉GMP含量有显著影响,GluA1位点亚基1>N,GluB1位点亚基13+16>7+9或7+8或14+15或17+18,GluD1位点亚基5+10>2+12,其他亚基差异不显著。说明含亚基1、13+16和5+10的品种能形成较多的GMP。HMWGS评分与面粉GMP含量的相关系数为0.288,达到极显著水平。     

不同品质类型小麦籽粒麦谷蛋白亚基及谷蛋白聚合体形成和累积动态

选用高分子量麦谷蛋白亚基(HMW-GS)组成不同的3个强筋和4个弱筋小麦品种,研究了其籽粒发育过程中麦谷蛋白亚基、谷蛋白聚合体的形成和累积动态。结果表明,强筋小麦籽粒HMW-GS和B区低分子量麦谷蛋白亚基(LMW-GS)从花后9～12d开始表达;而弱筋小麦从花后12～15d开始表达,即强筋小麦麦谷蛋白亚基开始形成时间早于弱筋小麦。各品种的HMW-GS一旦形成,其累积速度较快,花后27d基本达到稳定值,之后维持稳定量;而LMW-GS形成后,累积较慢,直到花后30d左右达到稳定量。3个强筋小麦品种籽粒灌浆期谷蛋白总聚合体百分含量(TGP%)和谷蛋白大聚合体百分含量(GMP%)累积动态趋势基本一致,即在花后12～30d一直持续增加,花后30d至成熟达到最大值并保持稳定水平。4个弱筋小麦TGP%和GMP%累积动态均表现为在花后12～24d(灌浆早中期)形成和持续累积,花后24d至成熟逐渐降低。麦谷蛋白亚基表达模式以及谷蛋白聚合体累积动态的差异可能是导致小麦强筋或弱筋品质形成的关键。     

磷肥对小麦籽粒HMW-GS积累及GMP粒度分布的影响

在112.5 kg hm^-2和225 kg hm^-2两种氮水平下,检测了施磷量对强筋小麦山农12籽粒高分子量谷蛋白亚基(HMW-GS)积累及谷蛋白大聚合体(GMP)粒度分布的调控效应。结果表明,小麦籽粒HMW-GS在花后14 d已形成, 成熟期籽粒HMW-GS含量表现为施磷处理高于不施磷处理。在低氮条件下,施磷有助于HMW-GS的积累,而在正常施氮条件下过多施磷则不利于其积累。在低氮条件下,粒径<10 μm GMP颗粒体积百分比随施磷量增加而显著降低;在正常氮水平下,施磷降低粒径<10 μm GMP颗粒体积百分比,其效应表现施磷0 kg hm^-2处理最大,其次为施磷40 kg hm^-2和100 kg hm^-2处理,施磷160 kg hm^-2处理最小。两种施氮水平下分别增施磷肥,粒径在10~100 μm和>100 μm GMP颗粒的体积百分比均呈现随磷肥用量增加而增加的趋势。在正常氮水平下,各施磷处理间籽粒中GMP颗粒数目百分比无明显差异。成熟期籽粒中HMW-GS含量与粒径<10 μm GMP颗粒体积百分比呈显著负相关,而与10~100 μm GMP颗粒体积百分比呈显著正相关。说明较大粒径GMP颗粒具有较高的HMW-GS含量。