麦类作物种子中戊聚糖研究进展

戊聚糖是谷物种子中, 特别是小麦种子中重要的非淀粉多糖, 也是麦类面粉的重要功能性成分,对面包品质有重要影响。由于戊聚糖在面包工业和保健品行业具有广阔的应用前景, 近50年来, 国外对其开展了较为系统和深入的研究。本文回顾了近年来有关戊聚糖的最新研究进展, 包括其组成、结构、含量及其测定方法以及在面包烘焙中的应用等。     

小麦籽粒中植酸、戊聚糖含量及其与相关性状关系的研究

选用不同基因型小麦,测定了籽粒中植酸、蛋白质及戊聚糖的含量,并对其进行遗传相关分析,结果表明：(1)各性状在品种间存在显著性差异,且植酸的广义遗传力比较低;(2)植酸含量与蛋白质含量呈极显著的正相关,与戊聚糖呈极显著负相关。通过对参试的18个不同基因型小麦中植酸和戊聚糖含量进行聚类分析,可以将18个基因型小麦聚为四类,并初步认为豫麦47是参试品种中最适宜于用作饲用小麦。     

河南若干小麦品种籽粒戊聚糖含量的初步研究

1999-2000年对河南省8个有代表性的小麦品种的戊聚糖进行了测定,不同品种戊聚糖的平均含量变化范围为6%-9%。不同品种和不同生态条件下小麦籽粒戊聚糖含量均有很大差异。5个试点小麦籽粒戊聚糖的平均含量与千粒重,降落值均成负相关关系（r=-0.83,r=-0.31),而与蛋白质的含量却呈正相关关系（r=0.35)。说明戊聚糖含量与生态因素有很大关系,采用Eberhart-Russell模型对小鼠戊聚糖含量的稳定性进行分析。发现豫麦34是戊聚糖含量较理想的品种。     

小麦高分子量麦谷蛋白亚基鉴定及其品质效应研究进展

高分子量谷蛋白亚基(HMW-GS,high molecular weight glutenin subunits)是小麦子粒贮藏蛋白的重要组成成分,其组成、搭配、表达水平及含量决定面团弹性和面包加工品质。本文主要介绍了小麦HMW-GS编码基因的克隆、分子特征、分子标记开发及其在小麦育种中的应用,并综述了不同HMW-GS与面粉加工品质之间的关系,以及HMW-GS基因遗传转化、微量配粉和突变体培育等方面的研究进展,分析了目前研究中存在的主要问题,认为通过分子标记辅助选择和转基因技术聚合优质亚基,培育优质面包小麦品种和明确各个HMW-GS基因的品质效应是今后的研究重点。     

小麦等谷类植物种子贮藏蛋白基因的表达与调控

高等植物在成熟期的主要生理过程是将蛋白质、淀粉和脂肪等贮藏在种子中。贮藏在种子中的蛋白质称为种子贮藏蛋白。小麦、水稻、玉米等粮食作物是人类和家畜摄取蛋白质的重要来源。研究贮藏蛋白基因在种子发育过程中的表达机制,是进一步应用生物技术改良作物的基础工作。1谷物     

细胞分裂素调控种子发育、休眠与萌发的研究进展

种子萌发是子代植株建立、生长和繁育的重要阶段, 在种子植物生命周期中起重要作用。种子休眠是在发育过程中形成的, 在生理成熟期达到峰值。种子休眠与萌发的植物激素调控可能是种子植物中一种高度保守的机制。细胞分裂素(CK)是植物体内的一种重要信号分子, 调控植物生长发育的许多方面。生物活性CK的水平由其生物合成、活化、失活、再活化和降解之间的平衡所调控, 种子的发育、休眠与萌发受生物活性CK的水平和信号转导途径调控。该文综述了CK的生物合成与代谢、信号转导以及对种子发育、休眠与萌发的调控作用, 提出了在本领域需要进一步研究的科学问题, 旨在为理解CK调控种子发育、休眠与萌发的分子机理提供参考。     

中国植物种子形态学研究方法和术语

强调了研究中国植物种子形态的重要科学意义和应用价值。介绍了种子形态学研究方法,其内容包括材料选择、形态描述、照相等。解释了常用种子形态学术语,包括种子状果实、种子各组成部分、种子表面及切面、附属物、种皮特化结构、质地等。     

有关植物人工种子研究的初报

人工种子是在离体培养条件下,由单个细胞产生分裂发育成一个胚状体,采用理化因素控制胚状体的同步生长,在胚状体表面包上一层有机化合物做为保护胚状体及提供营养的“种皮”,创造一个和种子相似的结构——人工种子。人工种子具有许多优越性,通过细胞悬浮培养产生的胚状体具有数量多(1升培养基可     

酸面团发酵剂在发酵面食品加工中的研究进展

综述了酸面团的种类、分离培养方法,以及在面包、馒头等发酵面食品加工中的应用研究进展。研究显示,酸面团可以改善面团的延伸性和可塑性等加工性能,提高制品膳食纤维、矿物质、B族维生素的有效性,以及氨基酸、多肽等生物活性物质的含量,是加工无面筋质面包、馒头,以及低糖高膳食纤维的功能性发酵面食品的良好选择。酸面团的特殊菌群提高了面包、馒头的抗霉菌污染性能和保水能力,在延长面包、馒头的货架期方面效果显著。     

野生花卉大百合属植物繁殖技术研究进展

大百合属(Cardiocrinum)植物是一类具有重要应用价值的野生花卉,对其繁殖技术体系的研究旨为推广应用奠定基础。从引种栽培、种子生理、组织培养等方面综述了大百合属繁殖技术的研究进展,认为利用种子和组培进行大量繁殖已成为可能,对其杂交育种还需进一步深入研究,今后也应对其进行现代生物技术的应用研究。     

New insights into the organization, recombination, expression and functional mechanism of low molecular weight glutenin subunit genes in bread wheat

The bread-making quality of wheat is strongly influenced by multiple low molecular weight glutenin subunit (LMW-GS) proteins expressed in the seeds. However, the organization, recombination and expression of LMW-GS genes and their functional mechanism in bread-making are not well understood. Here we report a systematic molecular analysis of LMW-GS genes located at the orthologous Glu-3 loci (Glu-A3, B3 and D3) of bread wheat using complementary approaches (genome wide characterization of gene members, expression profiling, proteomic analysis). Fourteen unique LMW-GS genes were identified for Xiaoyan 54 (with superior bread-making quality). Molecular mapping and recombination analyses revealed that the three Glu-3 loci of Xiaoyan 54 harbored dissimilar numbers of LMW-GS genes and covered different genetic distances. The number of expressed LMW-GS in the seeds was higher in Xiaoyan 54 than in Jing 411 (with relatively poor bread-making quality). This correlated with the finding of higher numbers of active LMW-GS genes at the A3 and D3 loci in Xiaoyan 54. Association analysis using recombinant inbred lines suggested that positive interactions, conferred by genetic combinations of the Glu-3 locus alleles with more numerous active LMW-GS genes, were generally important for the recombinant progenies to attain high Zeleny sedimentation value (ZSV), an important indicator of bread-making quality. A higher number of active LMW-GS genes tended to lead to a more elevated ZSV, although this tendency was influenced by genetic background. This work provides substantial new insights into the genomic organization and expression of LMW-GS genes, and molecular genetic evidence suggesting that these genes contribute quantitatively to bread-making quality in hexaploid wheat. Our analysis also indicates that selection for high numbers of active LMW-GS genes can be used for improvement of bread-making quality in wheat breeding.     

基因枪法获得无选择标记的1Dx5基因表达的转基因小麦

利用基因枪将无选择标记的优质高分子量麦谷蛋白亚基基因1Dx5导入新疆耐盐小麦品种新冬26,为利用优质基因进行小麦品质改良奠定基础。构建无选择标记的线性1Dx5表达框。利用基因枪将其转入不含该亚基的小麦品种新冬26幼胚盾片中,经PCR二分法筛选,从转化的1 000块幼胚盾片中共获得3株转基因阳性植株,转化效率0.3%。利用SDS-PAGE分析目的基因在转基因后代籽粒中的表达。转基因植株后代种子分析表明,1Dx5在转基因后代部分种子中表达。本研究成功地将无选择标记的线性1Dx5片段导入普通小麦新冬26中,并在后代部分种子中得到了表达。为利用优质亚基基因改良小麦加工品质奠定基础。     

Development of a new marker system for identifying the complex members of the low-molecular-weight glutenin subunit gene family in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Low-molecular-weight glutenin subunits (LMW-GSs) play an important role in determining the bread-making quality of bread wheat. However, LMW-GSs display high polymorphic protein complexes encoded by multiple genes, and elucidating the complex LMW-GS gene family in bread wheat remains challenging. In the present study, using conventional polymerase chain reaction (PCR) with conserved primers and high-resolution capillary electrophoresis, we developed a new molecular marker system for identifying LMW-GS gene family members. Based on sequence alignment of 13 LMW-GS genes previously identified in the Chinese bread wheat variety Xiaoyan 54 and other genes available in GenBank, PCR primers were developed and assigned to conserved sequences spanning the length polymorphism regions of LMW-GS genes. After PCR amplification, 17 DNA fragments in Xiaoyan 54 were detected using capillary electrophoresis. In total, 13 fragments were identical to previously identified LMW-GS genes, and the other 4 were derived from unique LMW-GS genes by sequencing. This marker system was also used to identify LMW-GS genes in Chinese Spring and its group 1 nulli–tetrasomic lines. Among the 17 detected DNA fragments, 4 were located on chromosome 1A, 5 on 1B, and 8 on 1D. The results suggest that this marker system is useful for large-scale identification of LMW-GS genes in bread wheat varieties, and for the selection of desirable LMW-GS genes to improve the bread-making quality in wheat molecular breeding programmes.     

Marker-assisted selection of high molecular weight glutenin alleles related to bread-making quality in Iranian common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Bread-making quality in hexaploid wheats is a complex trait. It has been shown that the amount and composition of protein can influence dough rheological properties. The high-molecular-weight (HMW) glutenins are encoded by a complex locus, Glu-1, on the long arm of group-1 homoeologus chromosome of the A, B and D genomes. In this work we used PCR-based DNA markers as a substitution tool to distinguish wheat bread-making quality. We detected PCR-based DNA markers for coding sequence of Glu-A1x, Glu-B1x and Glu-D1x to be 2300 bp, 2400 bp and 2500 bp respectively. DNA markers related to coding sequence of Glu-A1y, Glu-B1y and Glu-D1y were; 1800 bp, 2100 bp and 1950 bp, however, the repetitive region of their coding sequence were shown to be about 1300 bp, 1500 bp and 1600 bp. The results demonstrate that the size variation was due to different lengths of the central repetitive domain. Good or poor bread-making quality in wheat is associated with two allelic pairs of Glu-D1, designated 1Dx5-1Dy10 and 1Dx2-1Dy12. The 1Bx7 allele has moderate-to-good quality score. The specific DNA markers, of 450 bp, 576 bp, 612 bp and 2400 bp respectively were characterized for 1Dx5, 1Dy10, 1Dy12 and 1Bx7 alleles. These markers are very important in screening of wheat for bread-making quality.     

Stable expression of <Emphasis Type="Italic">1Dx5</Emphasis> and <Emphasis Type="Italic">1Dy10</Emphasis> high-molecular-weight glutenin subunit genes in transgenic rye drastically increases the polymeric glutelin fraction in rye flour

We generated and characterized transgenic rye synthesizing substantial amounts of high-molecular-weight glutenin subunits (HMW-GS) from wheat. The unique bread-making characteristic of wheat flour is closely related to the elasticity and extensibility of the gluten proteins stored in the starchy endosperm, particularly the HMW-GS. Rye flour has poor bread-making quality, despite the extensive sequence and structure similarities of wheat and rye HMW-GS. The HMW-GS 1Dx5 and 1Dy10 genes from wheat, known to be associated with good bread-making quality were introduced into a homozygous rye inbred line by the biolistic gene transfer. The transgenic plants, regenerated from immature embryo derived callus cultures were normal, fertile, and transmitted the transgenes stably to the sexual progeny, as shown by Southern blot and SDS-PAGE analysis. Flour proteins were extracted by means of a modified Osborne fractionation from wildtype (L22) as well as transgenic rye expressing 1Dy10 (L26) or 1Dx5 and 1Dy10 (L8) and were quantified by RP-HPLC and GP-HPLC. The amount of transgenic HMW-GS in homozygous rye seeds represented 5.1% (L26) or 16.3% (L8) of the total extracted protein and 17% (L26) or 29% (L8) of the extracted glutelin fraction. The amount of polymerized glutelins was significantly increased in transgenic rye (L26) and more than tripled in transgenic rye (L8) compared to wildtype (L22). Gel permeation HPLC of the un-polymerized fractions revealed that the transgenic rye flours contained a significantly lower proportion of alcohol-soluble oligomeric proteins compared with the non-transgenic flour. The quantitative data indicate that the expression of wheat HMW-GS in rye leads to a high degree of polymerization of transgenic and native storage proteins, probably by formation of intermolecular disulfide bonds. Even -40k secalins, which occur in non-transgenic rye as monomers, are incorporated into these polymeric structures. The combination 1Dx5 + 1Dy10 showed stronger effects than 1Dy10 alone. Our results are the first example of genetic engineering to significantly alter the polymerization and composition of storage proteins in rye. This may be an important step towards improving bread-making properties of rye whilst conserving its superior stress resistance.     

Novel and favorable QTL allele clusters for end-use quality revealed by introgression lines derived from synthetic wheat

Wheat quality is an important target trait. Previous studies mainly focus on storage protein, but their contribution to quality is partial, and most loci for quality are still undetected. Wild species of wheat are valuable resources for wheat improvement and introgression lines (ILs) are the ideal materials for detecting quantitative trait loci (QTL). In this study, a set of 82 BC5 F2-6 ILs, carrying a range of introgressed chromosome segments from a synthetic hexaploid wheat Am3 (Triticum carthlicum × Aegilops tauschii), was developed and genotyped with 170 microsatellite markers. QTL analysis was performed for 14 parameters, sodium dodecyl sulfate sedimentation volume, grain protein content (GPC), grain hardness and 11 mixograph parameters, associated with end-use quality of wheat, using the materials harvested in three environments. This led to the detection of 116 QTL, with c. 95% of the positive alleles contributed by Am3. Six important and novel genomic regions for bread-making quality were found on chromosomes 2D, 3A, 4A, 4B, 5A and 6A. These loci for bread-making quality showed pleiotropy and had large positive effects on several quality parameters with no or very weak negative effect on grain yield, thus demonstrating the value of synthetic wheat as a source of useful genetic variation for the improvement of bread wheat quality.     

PCR analysis to distinguish between alleles of a member of a multigene family correlated with wheat bread-making quality

Good or poor wheat bread-making quality is associated with two allelic pairs at theGlu-D1 complex locus, designated 1Dx5-1Dy10 and 1Dx2-1Dy12, respectively. The polymerase chain reaction (PCR) verified the presence of the HMW-glutenin 1Dx5 gene from genomic DNA extracted from part of the endosperm of a single dry seed, or a small amount of leaf or root tissue, of several bread-wheat cultivars. This easy, quick, and non-destructive PCR-based approach is proposed as a very efficient and safe alternative to standard procedures for selecting bread-wheat genotypes with good bread-making properties.