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1.
Cloning and functional analysis of high molecular weight wheat glutenin subunit (HMW-GS) 1By8 from Italy durum cultivar Simeto was carried out in this study. All HMW-GS from Simeto were separated and characterized by appropriate electrophoresis methods, reversed-phased high performance liquid chromatography (RP-HPLC) and mass spectrometry (MS). The complete gene encoding 1By8 subunit was amplified by allele-specific PCR primers, including an upstream sequence of 857 bp and an open reading frame (ORF) of 2166 bp encoding a mature protein of 720 amino acid residues. The promoter sequence, containing -300 element (cereal glutenin gene control element) and enhancer was highly conserved among HMW-GS genes. Comparison with the sequence of subunit 1By9 from bread wheat demonstrated 99% identity with the main difference being that the 1By8 subunit possesses an additional insertion of 15 amino acid residues (QYPASQQQPA QGQQG) at position 342 and two residue substitutions at position 78 (leucine/proline) and 442 (arginine/glutamine). The molecular weight differences between MALDI-TOF-MS and deduced amino acid sequence of the coding gene revealed the possibility of some kinds of post-translational modifications present in 1By8 subunit. The protein subunit expressed in Escherichia coli showed a very similar mobility to the endogenous 1By8 of Simeto on SDS-PAGE. The function of the isolated protein on wheat processing quality was determined by 10 g Mixgraph analysis. Results demonstrated that addition of y-type HMW glutenin subunits into the base flour had significant positive effects on main mixing parameters and significant difference in effects were observed among different y-type subunits.  相似文献   

2.
The x- and y-type high molecular weight (HMW) glutenin subunits are conserved seed storage proteins in wheat and related species. Here we describe investigations on the HMW glutenin subunits from several Pseudoroegneria accessions. The electrophoretic mobilities of the HMW glutenin subunits from Pd. stipifolia, Pd. tauri and Pd. strigosa were much faster than those of orthologous wheat subunits, indicating that their protein size may be smaller than that of wheat subunits. The coding sequence of the Glu-1St1 subunit (encoded by the Pseudoroegneria stipifolia accession PI325181) was isolated, and found to represent the native open reading frame (ORF) by in vitro expression. The deduced amino acid sequence of Glu-1St1 matched with that determined from the native subunit by mass spectrometric analysis. The domain organization in Glu-1St1 showed high similarity with that of typical HMW glutenin subunits. However, Glu-1St1 exhibited several distinct characteristics. First, the length of its repetitive domain was substantially smaller than that of conventional subunits, which explains its much faster electrophoretic mobility in SDS-PAGE. Second, although the N-terminal domain of Glu-1St1 resembled that of y-type subunit, its C-terminal domain was more similar to that of x-type subunit. Third, the N- and C-terminal domains of Glu-1St1 shared conserved features with those of barley D-hordein, but the repeat motifs and the organization of its repetitive domain were more similar to those of HMW glutenin subunits than to D-hordein. We conclude that Glu-1St1 is a novel variant of HMW glutenin subunits. The analysis of Glu-1St1 may provide new insight into the evolution of HMW glutenin subunits in Triticeae species.  相似文献   

3.
The high molecular weight glutenin subunits (HMW-GS) play a key role in end-use quality of wheat. Their particular primary structure is mostly derived from DNA sequencing, which gives no information on potential post-translational modifications. This paper reveals the primary structure of HMW-GS 1Dx2 by proteomic analysis. For this purpose, HMW-GS were first isolated from wheat flour (cv. Contra). The relative molecular mass (Mr) of subunit 1Dx2 present in the HMW-GS mixture was then very accurately determined with high-performance liquid chromatography–electrospray ionization-mass spectrometry using a quadrupole-time-of-flight mass analyzer (HPLC–ESI-QTOF-MS). The obtained Mr value (87,105) differed from the value derived from its protein sequence in the NCBI database (87,007). The subunit was further purified by preparative reversed-phase HPLC and partially hydrolyzed with chymotrypsin. The resulting 1Dx2 peptides were then analyzed by HPLC–ESI-MS/MS and the MS data were compared to amino acid sequences in protein databases. The discrepancy between the calculated and the measured Mr of 1Dx2 was explained by a missing proline in the 1Dx2 amino acid sequence from the database and not by any post-translational glycosylation.  相似文献   

4.
In this work we report the effects of the HMW-GS 1Ax1, 1Dx5 and 1Dy10 on the breadmaking quality of the bread wheat cultivar Anza that contains the HMW-GS pairs 1Dx2 + 1Dy12 and 1Bx7* + 1By8, and is null for the Glu-A1 locus. This allows the characterization of individual subunits 1Dx5 and 1Dy10 in the absence of subunit 1Dx5, and the interactions between these subunits and subunits 1Dx2 and 1Dy12 to be determined. Three transgenic lines termed T580, T581 and T590, containing, respectively, the HMW-GS 1Ax1, 1Dx5 and 1Dy10 were characterized over 3 years using a range of widely-used grain and dough testing methods. The transgenic subunits 1Ax1, 1Dx5 and 1Dy10 accounted for 25.2%, 20.3% and 17.9%, respectively, of the total HMW-GS in the three transgenic lines. Although lines T581 and T590 expressed similar levels of subunits 1Dx5 and 1Dy10 they had different effects on other aspects of protein composition, including changes in the ratios of glutenin/gliadin, of HMW/LMW-GS, the 1Dx2/1Dy12, the x-type/y-type HMW-GS and the proportions of high molecular mass glutenin polymers. In contrast, lines transformed to express subunits 1Ax1 and 1Dx5 showed similar changes in protein composition, with higher protein contents and decreased ratios of glutenin/gliadin and 1Dx2/1Dy12. In addition, both transgenic lines showed similar increases in the ratio of x-type/y-type subunits compared to the control line. The transgenic lines were analysed using Farinograph, Mixograph and Alveograph. This confirmed that the expression of all three subunits resulted in increased dough strength (and hence breadmaking quality) of the cultivar Anza. A beneficial effect of subunit 1Dx5 has not been reported previously, transgenic wheat lines expressing this subunit giving overstrong dough unsuitable for breadmaking. However, the expression of subunit 1Dy10 had a greater effect on breadmaking quality than subunits 1Ax1 and 1Dx5. The Farinograph parameters such as dough stability and peak time were increased by 9.2-fold and 2.4-fold, respectively, in line T590 (expressing 1Dy10) with respect to the control line. Similarly, the Mixograph mixing time was increased by four-fold and the resistance breakdown decreased by two-fold in line T590 compared with the control line. The Alveograph W value was also increased by 2.7-fold in line T590 compared to the control line. These transgenic lines are of value for studying the contribution of specific HMW-GS to wheat flour functional properties.  相似文献   

5.
To study the contributions of high-molecular-weight glutenin subunits (HMW-GS) to the gluten macropolymer and dough properties, wheat HMW-GS (x- and y-types) are synthesized in a bacterial expression system. These subunits are then purified and used to supplement dough mixing and extensigraph experiments through dough partial reduction and reoxidation to allow these exogenously added HMW-GS to incorporate into gluten polymers. Detailed results are given for seven mixing and two extension parameters. HMW-GS synthesized in bacteria behaved similarly under these conditions to the same HMW-GS extracted from wheat flour. These experiments initially focused on the HMW-GS of the D-genome of hexaploid wheat encoded at the Glu-D1 locus; e.g. the Dx2, Dx5, Dy10, and Dy12 subunits. Experiments used five different flours and results are shown to be consistent when normalized to results from Dx5. The incorporation of Dx-type subunits into the gluten disulfide bonded network has greater effects on dough parameters than incorporation of Dy-type subunits. When Glu-D1 x- and y-type subunits are incorporated together, there are synergistic effects greater than those with either subunit type alone. This synergistic effect was greatest with approximately equal amounts of Dx- and Dy-type subunits - implying a 1:1 stoichiometric relationship.  相似文献   

6.
The bread wheat elasticity, which is very important for bread-making quality, is largely determined by the composition of high-molecular-weight glutenin subunits (HMW-GS). The HMW-GS encoded by Glu-B1 loci are highly polymorphic and the combinations 17+18 and 14+15 are good for bread making. Thus it is very important to identify the alleles at Glu-B1 loci for wheat quality improvement. In this study, the five common HMW-GS types encoded by Glu-B1x locus carried by 18 Chinese bread wheat cultivars (or lines) were analyzed by SDS-PAGE. Two pairs of PCR primers which could distinguish the Glu-Blx alleles of the five common HMW-GS types were designed based on the Glu-B1x gene sequences (Reddy and Appels, 1993; Genbank accession: X13927; Genbank accession:AY367771). 22 recombinant inbred lines (RILs) derived from Jing711 (contains 17 subunit on Glu-B1x) and Pm97034 (contains 14 subunit on Glu-B1x) were used to validate the accuracy of the primers, which showed that the two specific markers could be used together to distinguish alleles at Glu-B1x locus and accelerate wheat quality breeding by marker assisted selection.  相似文献   

7.
A large collection of accessions of the wild wheat progenitor Triticum tauschii, the donor of the D genome of Triticum aestivum, was evaluated for the variability of high molecular weight (Mr) glutenin subunits by electrophoretic and chromatographic methods. A large range of allelic variation at theGlu-Dt1 locus was found in this collection and some novel subunits were observed in both x- and y-type glutenin subunits, including x- or y-type null forms. A few accessions showed three bands in the high Mrglutenin subunit region. However, only two subunits were observed when monomeric proteins were removed before SDS-PAGE analysis of polymeric proteins. The presence of monomeric proteins in this region is discussed. Characterisation of these subunits was also carried out by reversed phase-high performance liquid chromatography (RP-HPLC). Very different surface hydrophobicities were observed between x- and y-type subunits and in some cases it was possible to identify glutenin subunits with the same apparent molecular weight but different surface hydrophobicity. Differences in elution times that were detected when the same subunit was either reduced or reduced and alkylated were related to the number of cysteine residues present in each glutenin subunit. The newGlu-Dt1 glutenin subunits have the potential to enhance the genetic variability available for improving the quality of bread wheat (T. aestivum).  相似文献   

8.
The effect of lowMrwheat protein addition on the amount and composition of the glutenin macropolymer (GMP) of dough was investigated for the three wheat cultivars Obelisk (weak), Camp Remy (medium strong) and Rektor (strong). During mixing, the amounts of high and lowMrglutenin subunit classes, and of the individual subunits decreased. The proportion of highMrglutenin subunits decreased and that of lowMrglutenin subunits increased, indicating an inhomogeneous distribution of the two subunit classes within the polymers present in GMP. During resting, the amounts of the glutenin subunit classes and of individual subunits increased. Meanwhile, the proportion of highMrglutenin subunits in GMP increased. LowMrwheat protein addition retarded re-polymerisation in that the amounts of glutenin subunit classes and of individual highMrglutenin subunits in GMP increased less than without addition. The proportion of highMrglutenin subunits in GMP directly after mixing was also decreased by lowMrwheat protein addition, and the proportion increased faster during dough resting, compared with the GMP in dough without lowMrwheat protein addition. Eventually, after 90 or 135 min resting, no differences existed in the proportions in GMP from doughs with and without lowMrwheat protein addition. LowMrwheat protein addition had no specific effect on individual highMrglutenin subunits, nor on the x-type/y-type subunit ratio in the GMP. In contrast, with increasing lowMrwheat protein addition, a highly significant reduction in the subunit 10 or 12/subunit 9 ratio in GMP was observed. This finding is in line with the decrease in this ratio directly after mixing in GMP of the dough without lowMrwheat protein addition. Since no specific effects were observed, it can be concluded that the lowMrwheat protein acts rather unspecifically on the GMP of dough.  相似文献   

9.
Intermediate wheatgrass (Thinopyrum intermedium) is a perennial crop that possesses desirable agronomic traits and provides environmental services, e.g., reducing soil erosion, nitrate leaching and inputs of energy and pesticide. Thus, intermediate wheatgrass is currently being domesticated as a perennial grain crop. However, the genetic information for molecular breeding is quite limited. Here we report a molecular analysis of high-molecular-weight glutenin subunits (HMW-GS) in intermediate wheatgrass using gene cloning and protein biochemistry. Five HMW-GS genes were isolated from individual intermediate wheatgrass plants: two x-type genes TiHGS1 and TiHGS4, and three y-type genes TiHGS2, TiHGS3 and TiHGS5. Among them, TiHGS5 was novel and possessed an additional cysteine residue at the N-terminal domain or repetitive domain. Sequence alignments showed that TiHGS1 and TiHGS2 genes shared high identities (>96%) with the Glu-1Dx and Glu-1Dy genes, respectively, in common wheat and Aegilops species, TiHGS3 with HMW-GS genes from Dasypyrum or Pseudoroegneria, and TiHGS4 and TiHGS5 with HMW-GS genes from Thinopyrum elongatum. This work provides substantial new insights into the gene compositions and protein profiles of HMW-GS in intermediate wheatgrass, and also gives evidence about the genome components of intermediate wheatgrass.  相似文献   

10.
HighMrglutenin subunit 20 and its linked y-type subunit, present in the durum wheat cultivar Lira, were purified by preparative reversed-phase high-performance liquid chromatography (RP–HPLC). Amino acid and N-terminal sequence analysis of subunit 20y confirmed that it corresponded to a y-type subunit. Moreover, the number and position of the cysteine residues in subunit 20 were determined by alkylation with the fluorogenic reagent 7-fluoro-4-sulfamoyl-2,1,3,-benzoxadiazole (ABD-F) and subsequent enzymic digestion with trypsin. N-terminal amino acid sequence analysis of the fluorescent peptides showed that subunit 20 had only two cysteine residues, one in the N-terminal region and the other in the C-terminal domain.  相似文献   

11.
Electrophoretic and reversed phase high performance liquid chromatographic (RP–HPLC) analyses were performed on gluten proteins extracted from flours milled from two different Swedish bread wheat lines; these lines have been reported to possess a novel highMrglutenin subunit controlled by a gene at theGlu-A1locus, referred to as 21*. Although RP–HPLC indicated that subunit 21* has a surface hydrophobocity similar to that of the commonly occurring allelic subunits 1 or 2*, it differs from them in isoelectric point, being more basic when analysed by two dimensional gel electrophoresis (IEF/SDS–PAGE). RP–HPLC separations of highMrglutenin subunits showed the presence of an additional peak, the behaviour of which was similar to that of y-type subunits encoded by genes at theGlu-A1ylocus and present only in wild wheatsT. urartu(AA) orT. dicoccoides(AABB). Based on chromatographic results and on the tight linkage observed with subunit 21*, it is suggested that the additional component (indicated as 21*y), present in the breeding lines analysed, corresponds to the y-type subunit encoded at theGlu-A1locus. Genes encoding the subunits 21* and 21*y were also analysed by polymerase chain reaction (PCR). Contrary to what was observed for the polypeptide itself, the gene corresponding to subunit 21* was similar in size to that encoding subunit 2* and shorter than that corresponding to subunit 1. Moreover, the amplification product corresponding to the active 21*y gene was shorter than that of the allelic inactive gene present in the bread wheat cultivar Cheyenne. As reported for other highMrglutenin subunits, gene size differences observed were due to a different length of the repetitive region. Because cultivated polyploid wheats have been shown to have only the x-type subunit at theGlu-A1locus, it is speculated that the new combination, with both x- and y-type subunits expressed, might have been introgressed during breeding processes from the wild wheat progenitorsT. urartuorT. dicoccoides, which have genotypes expressing both types of subunits.  相似文献   

12.
Electrophoretic (urea SDS–PAGE) and chromatographic (RP–HPLC) analysis was performed on 8 allelic variants of HMW glutenin subunits derived fromTriticum tauschiiand from the D genome of a hexaploid wheat species (Triticum macha) and hexaploid landraces. These subunits had been previously identified using SDS–PAGE. The characterisation revealed that subunits Dy10tand Dy12tfromT. tauschiicould be differentiated from their bread wheat counterparts using both urea SDS–PAGE and RP–HPLC. In the latter case, theT. tauschiiy-type subunits were clearly more hydrophobic than the Dy type subunits of bread wheat. The characterisation also suggested that subunit Dx5t, derived from two separateT. tauschiiaccessions, did not contain the extra cysteine residue characteristic of Dx5 from bread wheat. RFLP analysis of the genes encoding the HMW glutenin subunits of interest suggested that the absence of Dx-type HMW glutenins in two hexaploid landraces was due to lack of expression of their encoding genes. The relationship betweenHindIII DNA fragment size and protein subunit size, as measured by electrophoretic mobility, is examined and discussed. Finally, the solubility properties of a HMW protein designated T1 (derived fromT. tauschiiaccession AUS 18913) suggested that it was not a HMW glutenin subunit as was previously thought. Further studies are needed to clarify the identity of this subunit.  相似文献   

13.
Brachypodium distachyon, an emerging model plant system for some economically important temperate grasses such as wheat, barley and switchgrass, has recently caught wide attention in modern biological research. In the current study, the glutenin, albumin and globulin components of 13 B. distachyon accessions were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) followed by peptide mass finger printing (PMF) and MS/MS protein identification. Abundant wheat low molecular weight glutenin subunit (LMW-GS) like proteins and a few high molecular weight glutenin subunits (HMW-GS) with low expression level were detected in B. distachyon. A total of 18 storage proteins and 15 albumin proteins were identified through PMF and MS/MS. The results demonstrated that the major seed storage proteins in B. distachyon are wheat LMW-GS like proteins and globulins. The identified albumins and globulins were mostly various enzymes that were classified into five groups according to their functions. The 2-DE spot distribution and MS results suggested that post-translational modifications (PTMs) such as phosphorylations and glycosylations are common phenomena in B. distachyon seed proteome.  相似文献   

14.
The mixing properties of the dough are critical in the production of bread and other food products derived from wheat. The high molecular weight glutenin subunits (HMW-GS) are major determinants of wheat dough processing qualities. The different alleles of the HMW-GS genes in hexaploid wheat vary in their effect on dough quality. To determine the contribution of the individual HMW-GS alleles, lines deficient in HMW-GS proteins were generated by chemical mutagenesis in the elite bread wheat Triticum aestivum cv. Summit. In this report we describe the identification and characterization of Dy10 and Ax1 deficient lines. Examination of the effect of Dy10 and Ax1 deficiency on dough rheological properties by mixography showed shorter mixing time to reach peak resistance, and weaker and less extensible doughs relative to the wild type control. This is the first time that the role of Dy10 in vivo has been examined apart from the Dx5 + Dy10 allelic pair combination.  相似文献   

15.
为了克隆节节麦中的HMW-GS基因,利用十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)分析了节节麦的HMW-GS,发现1种编码序列未知的y-型亚基,即Dy8.1t亚基。通过对目的片段的AS-PCR扩增、克隆、测序和氨基酸序列推导,发现这种未知序列具有典型HMW-GS的序列结构特征。通过与已知亚基序列比较发现,Dy8.1t与Dy10t、Dy10.4t、Dy10.5t和Dy12t在N-端序列有一个氨基酸差别(R-G)。与已知氨基酸序列的HMW-GS多序列比对和系统进化关系分析,证实Dy8.1t亚基是D基因组编码的高分子量谷蛋白y-型亚基家族的新成员。  相似文献   

16.
为探究陕西关中地区小麦HMW-GS亚基与品质性状间的关系,采用SDS-PAGE法对57份陕西关中地区小麦品种（系）HMW-GS亚基组成及相关品质性状进行了分析。结果表明,供试品种（系）中共检测出7种HMW-GS亚基类型和8种HMW-GS亚基组合;Glu-A1位点上有3种亚基类型,分别为1、2*和Null,以1亚基为主（78.95%）;Glu-B1位点上检测到7+8（61.40%）与7+9（38.60%）两个类型;Glu-D1位点上检测到5+10（70.18%）和2+12（29.82%）两个类型。3个HMW-GS基因位点编码亚基共组成8种亚基组合,品质得分6～10分,其中1/7+8/5+10组合品质得分10分,出现频率最高。就HMW-GS不同位点对品质性状效应进行分析发现,Glu-D1位点对b*值、形成时间、稳定时间、弱化度和粉质质量指数的影响达到极显著水平（P＜0.01）;对面团流变学特性的影响,Glu-D1>Glu-B1。不同类型亚基对小麦品质的效应存在差异,7+8亚基对蛋白质含量、湿面筋含量和容重具有正效应,7+9和5+10亚基对形成时间和稳定时间的影响显著高于其他亚基（P＜0.05）;携带1/7+8/5+10亚基组合小麦的蛋白质、湿面筋含量和容重最高;携带1/7+9/5+10亚基组合具有较高面粉L*值和面团流变学特性指标值。  相似文献   

17.
We have determined the technological properties of four lines containing combinations of three HMW-GS transgenes, encoding HMW-GS 1Ax1, 1Dx5 and 1Dy10. These lines were produced by conventional crossing of three single transgenic lines of the bread wheat cultivar Anza that contains the endogenous HMW-GS pairs 1Dx2 + 1Dy12 and 1Bx7* + 1By8 and is null for the Glu-A1 locus. Consequently, the total number of HMW-GS ranged from 4 in the control line Anza to 7 in line T618 which contains all three HMW-GS transgenes. The lines were studied over two years using a range of widely used grain and dough testing methods. All lines with transgenic subunits showed higher levels of glutenin proteins than the Anza control, and these differences were highly significant for lines T616, T617 and T618, containing, respectively, the transgenes encoding HMW-GS 1Ax1 and 1Dy10, 1Dx5 and 1Dy10 and 1Ax1, 1Dx5 and 1Dy10. These increases in glutenin levels are compensated by lower levels of gliadins present in transgenic lines. These changes affected the ratio of polymeric to monomeric gluten proteins (poly:mono), the ratio of HMW-GS to LMW-GS (HMW:LMW) and the contents of individual 1Ax, 1Bx, 1By, 1Dx and 1Dy subunits. Transgenic lines expressing subunit 1Dy10 together with x-type subunits (T616, T617 and T618) were superior to line T606, which had only increases in x-type subunits. In particular, the combination of transgenic subunits 1Dx5 and 1Dy10 (line T617) gave better dough rheological properties than the other combinations of transgenic subunits. For example, dough development time and stability were increased by 3.5-fold and 8.5-fold, respectively, while the mixing tolerance index (MTI) was decreased by 3.3-fold in line T617 with respect to the control line. Alveograph analyses showed that all four transgenic combinations had increased P values compared to the Anza control but subunit 1Dx5 greatly reduced the extensibility (L). These results show that stacking HMW-GS transgenes by conventional crossing is a valid strategy for the improvement of wheat quality, with different effects being related to the different HMW-GS combinations.  相似文献   

18.
为了建立准确有效小麦HMW-GS的检测方法,提高优质小麦品种鉴定和筛选效率,以已知HMW-GS组成的16份小麦品种为对照,优化完善SDS-PAGE结合分子标记检测小麦HMW-GS的方法,并对103份宁夏小麦品种进行了验证和分析。结果表明,8.5%的分离胶可以有效区分除了 Glu-B1位点的7*、7OE与8*亚基之外的其他亚基,分辨效果优良;SDS-PAGE结合 Bx7OE、 Bx7*/Bx7和 By8基因的分子标记可以准确鉴定小麦HMW-GS。在103份宁夏小麦品种中,发现15种HMW-GS和29种组合类型;首次在该地区小麦品种的 Glu-B1位点检测出了携带7OE、7*和8*亚基的品种;1/17+18/5+10为当地小麦HMW-GS的优势亚基组合类型,占20%。自1970年至2010年,HMW-GS的优质亚基（1、17+18和5+10）的出现频率呈明显增长趋势;宁夏小麦的HMW-GS种类和优质亚基出现频率随品种更换呈增加趋势。综上所述,分离胶浓度为8.5% 的SDS-PAGE和 Bx7OE、 Bx7*/Bx7和 By8分子标记的方法可准确有效地检测小麦HMW-GS组成,此方法可用于优质小麦品种的鉴定和筛选。  相似文献   

19.
Molar fractions of the high-molecular-weight glutenin subunits (HMW-GS) were determined for flour from bread wheat (Triticum aestivum L. cv Butte86) produced under 13 different combinations of temperature, water and mineral nutrition. Albumins, globulins and gliadins were removed from the flour by extraction with 0.3 M NaI in 7.5% 1-propanol. Total HMW-GS were recovered by extracting the remaining protein with 2% SDS and 25 mM DTT. Individual HMW-GS were then separated and quantified by RP-HPLC. Constant molar fractions for the five HMW-GS were maintained under all environmental conditions, despite large differences in duration of grain fill, total protein per grain, flour protein percentage, and total HMW-GS per grain. Similar molar fractions were found for five other US wheat varieties. The Bx7 subunit accumulated to the highest level at 30% of total HMW-GS. The Dx and Dy subunits were present in smaller but nearly equal proportions, 22% and 23%, respectively, and the Ax and By subunits were the least abundant, 14% and 12%, respectively. Although the amounts of HMW-GS per unit of flour are strongly affected by environment, the different subunits respond so similarly to external conditions that their final proportions appear to be determined mainly by genetic factors.  相似文献   

20.
A number of primers were designed which target DNA sequence variation of the coding and /or promoter regions of wheat HMW glutenin y-type genes located at the Glu-B1 locus. This allowed the development of a set of PCR-based markers for specific HMW glutenin genes encoding By-subunits for which no markers were previously available. Markers were validated using test cultivars containing specific Glu-B1 alleles confirmed by SDS-PAGE and RP-HPLC analysis. Among the specific markers developed, primer pair ZSBy8F5/R5 was specific for the By8 gene, which exists in Glu-B1b (Bx7+By8) and Glu-B1u (Bx7*+By8) alleles. This marker allows discrimination of alleles containing By8 and By8* that are usually difficult to distinguish using SDS-PAGE. Since the over-expressed Glu-B1 allele (Glu-Bl al.) contains the By8* subunit, it is possible to use this marker in breeding programs for selecting for the over-expression of subunit Bx7 in crosses that segregate between normal Bx7 and over-expressed Bx7 subunits. This marker also represents an alternative for distinguishing two common Glu-B1 alleles: Glu-B1i (Bx17+By18) and Glu-B1b (Bx7+By8). Two primer pairs ZSBy9aF1/R3 and ZSBy9F7/R6 both gave characteristic banding patterns for Glu-B1c (Bx7+By9) and can therefore be used to discriminate By9 - containing alleles from non - By9 alleles. Primer pair ZSBy9F2/R2 produced amplicons with a diagnostic banding pattern for allele Glu-B1f (Bx13+By16) and also permitted the discrimination of Glu-B1h (Bx14+By15) and Glu-B1e (Bx20) that have opposing genetic effects on wheat quality and are difficult to discriminate by SDS-PAGE.  相似文献   

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