水稻糯性突变对淀粉理化特性的影响

比较了籼、粳两个糯性突变品种与原亲本品种淀粉的理化特性。糯性突变后除了直链淀粉含量显著降低外,淀粉的糊化温度变高、胶稠度增大、RVA谱(rapid viscosity analyzer)参数下降。RVA谱参数降低的幅度从高到低依次是消减值>回复值>冷胶粘度>热浆粘度>最高粘度>崩解值,表明控制直链淀粉含量的Wx位点对淀粉糊化特性和粘滞性是有影响的,存在多效性。同时,两个糯稻品种之间的RVA谱差异较大,其中崩解值和最高粘度差值均大于糯性突变对它们的影响,说明除直链淀粉外,支链淀粉也影响淀粉的理化特性。对Wx位点鉴定的结果显示扬辐糯4号wx基因第一内含子剪切位点＋1位的碱基由原品种的G突变成了T,扬糯2号与其原品种相同(均为T);两个糯稻突变品种wx基因前导区的(CT)n微卫星重复序列与原品种相比都发生了变化。     

小麦淀粉合成酶SSⅡa基因克隆及生物学分析

淀粉合成酶SSⅡa基因是小麦淀粉合成中的关键酶基因。为了从分子水平上了解造成不同小麦品种（系）淀粉含量差异的原因,本研究根据GeneBank中的SSⅡa基因序列AF155217.2设计引物,对8个不同抗性淀粉含量的小麦品种（系）SSⅡa基因进行克隆和多态性分析,并对其氨基酸序列进行结构域预测。结果表明,8个品种的SSⅡa基因序列高度保守,与GeneBank中已发表的序列相似度达98.19%以上,共发现40个单核苷酸变异,导致20个氨基酸发生了变异。蛋白结构域分析发现这些变异位点均位于α-淀粉催化酶氨基N-末端外侧,而在α-淀粉催化酶的催化区域并未发现变异位点。另外,在新春12中,还发现了一个缺失位点,缺失片段为249 bp,该缺失片段包含了糖基转移酶的部分位点。本研究为进一步从分子水平理解SSⅡa基因的结构与抗性淀粉含量之间的关系及开发分子标记辅助选择育种提供了序列信息。     

不同生态环境对四川小麦品种(系)籽粒淀粉含量及理化特性的影响

为了明确不同生态点对不同小麦品种籽粒淀粉含量及理化特性的影响,对四川省27个小麦品种(系)在四个生态点(温江、西昌、崇州、仁寿)3年的籽粒淀粉总含量、直链/支链淀粉比例(直/支比)以及小麦淀粉糊化温度等参数进行了分析。结果表明,同一个生态点的小麦淀粉品质指标在不同年份间没有显著差异;同一性状在不同生态点间存在一定的差异,仁寿地区的小麦淀粉直/支比和直链淀粉含量显著高于其他三个生态点,总淀粉含量显著高于崇州点;仁寿和崇州地区的小麦淀粉糊化初始温度显著高于其他两个生态点,且仁寿地区的小麦淀粉糊化峰值温度和结束温度均显著高于温江地区。淀粉组成对淀粉的糊化特性有一定影响,且总淀粉含量、直链淀粉含量、直/支比与淀粉的糊化特性之间均存在显著正相关关系。不同气象因子对小麦淀粉不同品质指标影响程度不同,其中,降雨量、温度和光照时间对大多数淀粉品质指标有显著影响。     

小麦籽粒淀粉合成动态及糊化特性的基因型差异

为了明确不同基因型小麦品种籽粒灌浆过程中的淀粉合成动态,为小麦的高产优质栽培提供参考信息,对6个不同基因型小麦籽粒形成过程中淀粉组分的变化及淀粉糊化特性进行了分析。结果表明,非糯性小麦的直链淀粉含量随着花后天数的增加呈上升的趋势,糯性小麦则呈先上升后下降的趋势,所有品种的支链淀粉含量均呈上升的趋势;不同基因型小麦直链、支链淀粉积累速率均呈单峰曲线图,不同品种直链淀粉最大积累速率出现的时间不同,而支链淀粉最大积累速率出现的时间均在花后21d;不同小麦品种的峰值粘度、低谷粘度、最终粘度均随着花后天数的增加而上升;不同品种淀粉糊化特性不同:糯性小麦之间在糊化时间、反弹值上无差异,而在峰值粘度、低谷粘度、最终粘度、稀懈值上的差异达显著水平;对于非糯性小麦,豫麦50和其他品种的多数糊化参数差异达显著水平;糯小麦和非糯小麦在糊化参数上的差异达1%显著水平。     

稻米主要食味品质基因型与环境互作分析及其相关性研究

以南方稻区企业水稻区试联合体长江中下游中籼迟熟组3个区试点的24个杂交水稻品种为试验材料,进行了稻米糊化温度和直链淀粉含量的基因型、环境以及基因型与环境互作的分析。结果表明,糊化温度和直链淀粉含量的基因型和环境差异均达到极显著水平,基因型效应大于环境及基因型与环境互作效应。同时分析了糊化温度和直链淀粉含量与其他品质性状的相关性。相关分析结果表明,糊化温度与透明度呈极显著负相关,与直链淀粉含量呈负相关但未达显著水平;直链淀粉含量与垩白度、垩白粒率呈极显著正相关。     

小麦灌浆相关基因TaGIF1的克隆及表达分析

GIF1( grain incomplete filling 1)编码了一种质外体途径中催化蔗糖不可逆水解的细胞壁蔗糖转化酶,主要在组织生长旺盛并且需要供能的库中表达,是影响灌浆的关键基因。根据水稻 OsGIF1基因序列,同源克隆了普通小麦第2部分同源群染色体上的 TaGIF1基因,它包含7个外显子和6个内含子,与水稻OsGIF1基因结构相似。小麦 TaGIF1-2A基因含有237 bp的5′UTR、1 986 bp的ORF、262 bp的3′UTR,编码661个氨基酸。通过分析15份大小粒小麦品种的gDNA序列,在 TaGIF1-2A基因中共发现21个SNP位点,9个位于编码区,12个位于非编码区。SNP分组发现,15份大小粒小麦品种中 TaGIF1-2A基因共存在8种单倍型。氨基酸序列比对显示,共存在2个氨基酸变异位点,其余SNP位点未引起氨基酸的改变。大小粒品种中无特异SNP变异,表明该基因编码区序列高度保守。就 TaGIF1-2A启动子区而言,大粒材料元件数量和种类均多于小粒材料,而且这些元件均与籽粒发育相关,说明 TaGIF1-2A基因启动子的活跃程度与最终籽粒灌浆饱满度的形成可能存在密切联系。qRT-PCR分析表明, TaGIF1-2A在籽粒和颖壳中都有表达,在不同小麦材料中表达模式相同,说明与籽粒大小无关;而在2～6 DAA的籽粒中,表达量剧烈上调,而后急剧下调,由此推测 TaGIF1-2A可能影响籽粒灌浆,在灌浆前期与籽粒发育密切相关。亚细胞定位结果表明,TaGIF1-2A主要作用在细胞壁上。     

茶氨酸合成酶基因的SNP挖掘和遗传定位

茶氨酸合成酶(Theanine synthetase,TS)基因是茶树茶氨酸代谢过程中的关键酶基因。本研究以氨基酸含量差异明显的亲本及其杂交所得F_1子代为研究材料,克隆TS基因的c DNA序列,挖掘其SNPs位点,并成功将杂合SNP位点定位在遗传连锁群上。研究结果显示,通过序列比对在亲本间检测到3个SNPs,验证得到1个杂合的位点SNP735。将此位点成功转化为dCAPS标记,该标记在子代中的基因型分离比为1∶1,利用该群体已构建的茶树遗传图谱进行遗传定位,将dCAPS标记定位在连锁群LG03上,相邻标记为TM299和TM517。联合此标记及其相邻标记与游离氨基酸总含量和茶氨酸含量进行统计分析,表明具有显著的相关性。     

小麦淀粉与面条质量关系的研究进展

小麦淀粉品质对白盐面条的质量（尤其是煮后的感官特性）有重要影响。直链与支链淀粉的含量及比例是影响面条质量的重要因素,是造成不同小麦品种淀粉糊化和膨胀特性及面条质量差异的物质基础。较低直链淀粉含量的小麦粉具有较好的糊化和膨胀特性,制作的面条煮制时吸水率高,烹调损失低,具有较高的感官评分。优质白盐面条的直链淀粉含量应在22%左右。峰值黏度、稀懈值、峰值时间是影响面条质量的重要糊化参数,这3项参数高的小麦粉适合制作优质面条。高膨胀势或膨胀体积的小麦粉制作的面条中等偏软,光滑且富有弹性,可以作为面条用小麦的重要选择标准。一般认为,直链淀粉含量较低、峰值黏度和稀懈值高、峰值时间长、膨胀势或膨胀体积高的小麦粉适合制作优质白盐面条。其中,直链淀粉含量、峰值黏度和膨胀势是优质面条小麦评价的关键品质性状。     

粳稻杂种后代胚乳可溶性淀粉合成酶及同工型基因表达特性分析

以籽粒直链淀粉含量为选择指标,从东农423×藤系180F2代起连续定向选择培育成的籽粒直链淀粉含量有显著差异的F10后代东农1006(直链淀粉含量为18.82%)、东农1012(直链淀粉含量为7.70%),同样,从系选1号×通769后代中选出东农1001(直链淀粉含量为17.51%)、东农1024(直链淀粉含量为7.40%)比较分析了灌浆过程中籽粒直链淀粉含量和可溶性淀粉合成酶活性及同工型基因表达量等变化特征。结果表明,灌浆不同时期籽粒直链淀粉含量低的后代及亲本直链淀粉量始终低于直链淀粉含量高的后代及亲本;成熟期籽粒直链淀粉含量低的亲本和后代籽粒支链淀粉含量均显著高于籽粒直链淀粉含量高的亲本和后代,抽穗后10d、17d、24d的籽粒直链淀粉含量与支链淀粉含量间均呈负相关,但相关未达显著水平;抽穗后10d、17d、24d的可溶性淀粉合成酶活性与籽粒直链淀粉含量的相关系数分别为0.8115**,-0.7554*,-0.5957,与支链淀粉含量的相关系数分别为-0.0694,0.5453,-0.0207;在灌浆过程中亲本及后代的胚乳OsSSSⅠ、OsSSSⅡ-1、OsSSSⅡ-3、OsSSSⅢ-1和OsSSSⅢ-2基因随籽粒灌浆进程其mRNA转录表达量逐渐增加,达到峰值后又逐渐下降,呈单峰曲线变化;而OsSSSⅢ-2和OsSSSⅣ-2基因mRNA转录表达量在灌浆各时期都比其他基因大;灌浆不同时期直链淀粉含量高的后代与高亲相比、直链淀粉含量低的后代与低亲相比,既有转录表达量增加的基因,也有降低的基因;可溶性淀粉合成酶活性与OsSSSⅠ、OsSSSⅡ-3、OsSSSⅢ-2的mRNA转录表达量正相关,相关达显著水平;与OsSSSⅡ-1、OsSSSⅣ-2的mRNA转录表达量正相关,但相关未达显著水平,与OsSSSⅢ-1的mRNA转录表达量呈负相关,但相关未达显著水平。     

玉米胚乳突变基因ae1和du1的遗传效应

利用玉米ae1和du1隐性纯和突变自交系与普通玉米自交系48-2的杂交F₁、F₂代子粒为研究材料,通过单粒法测定子粒的直链淀粉含量和重量,用于分析玉米胚乳突变基因ae1和du1的遗传效应。结果表明：F₂代中具有ae1或者du1纯和突变的子粒表皮皱缩,重量明显下降,直链淀粉含量显著提高。在ae1与du1的杂交后代中,子粒的单粒重和直链淀粉含量没有显著变化,表明ae1与du1双突变并不能导致直链淀粉含量增加。单突变的ae1和du1群体内各子粒间的直链淀粉含量和重量差异较大,说明遗传背景中存在影响直链淀粉含量的修饰基因,表明在选育高直链淀粉玉米品系时,应当重视遗传背景的选择和修饰基因的累加。采用单粒法技术对分离后代进行直链淀粉含量和重量选择,有利于积累高直链淀粉修饰基因,是选育子粒饱满、高粒重的高直链淀粉玉米自交系的有效方法。     

The Null-4A Allele at the Waxy Locus in Durum Wheat affects Pasta Cooking Quality

Granule-bound starch synthase, also known as the waxy protein catalyses the synthesis of amylose in wheat endosperm starch. In durum wheats, the genes encoding GBSS are present at the two Wx loci on chromosome 7A and 4A (a segment of 7B that has been translocated). Several null Wx-B1 (missing GBSS protein from chromosome 4A) durum lines were produced from crosses with null-4A bread wheats backcrossed to durum wheats. Semolina milled from 4 normal and 7 null-4A durum wheat lines grown over two seasons (1999 and 2000) in South Australia were analysed for amylose content, starch pasting properties as measured by the Rapid Viscoanalyzer (RVA), swelling power and starch damage, protein content and electrophoretic protein analysis. Spaghetti was prepared with a micro-scale extruder and the cooked pasta evaluated for cooking loss, firmness, stickiness and water absorption. The null-4A lines had significantly lower (ca. 5%) amylose content, higher starch peak viscosities and semolina swelling power. The pasta derived from the null-4A lines had lower cooking loss and in 1999 was more adhesive than the non-waxy lines. Cooking loss was correlated with amylose content, peak starch viscosity, swelling power of semolina and cooked pasta adhesiveness. Semolina swelling power was highly correlated with RVA peak viscosity. Waxy durum wheats appear to have an advantage over the normal types in terms of lower cooking loss, widely used as an indicator of pasta cooking quality.     

施氮量对糯小麦和非糯小麦籽粒淀粉组分与理化特性的影响

为探明氮肥对小麦籽粒淀粉组分和理化特性的影响,采用田间试验,分析了4个施氮量(0、100、200、300kg·hm~(-2))对糯小麦(农大糯50222)和非糯小麦(轮选987)籽粒淀粉组分与理化特性的影响。结果表明,随施氮量的增加,小麦籽粒淀粉含量降低,轮选987籽粒中B型淀粉粒的数目占比增加,而农大糯50222籽粒的B型淀粉粒数目占比呈减少趋势;增施氮肥能显著提高小麦籽粒淀粉的峰值黏度和谷值黏度。相同施氮量处理下,轮选987淀粉的被测糊化特征参数(除谷值黏度外)均大于农大糯50222。施氮量不同,2个品种籽粒淀粉X-衍射图谱中各峰的位置和相对强度明显不同。随施氮量的增加,轮选987淀粉的相对结晶度增大,而农大糯50222淀粉的相对结晶度减小。相关分析表明,小麦籽粒的直链淀粉含量和直支比与最终黏度、稀澥值、反弹值、糊化温度和峰值时间呈显著正相关,与谷值黏度和相对结晶度呈显著负相关;支链淀粉含量反之。小麦籽粒的B型淀粉粒数目占比与峰值黏度、稀澥值呈显著负相关。综上所述,施氮量可影响小麦籽粒的淀粉含量和粒度分布,进而改变其糊化特性和晶体特征。     

Genetic and Environmental Variation in Sorghum Starch Properties

Starch was isolated from eight local Zimbabwean landrace varieties, an improved cultivar (SV2) and a hybrid (DC-75) of sorghum grown in four environments. Amylose content, pasting (peak (PV), hot-paste (HPV), cool-paste (CPV) viscosity), textural and thermal (gelatinisation peak temperature (T_p) and gelatinisation energy (ΔH)) properties of the starches were determined. The F -tests from analyses of variance detected significant (p<0·001) differences among genotypes and growing environments for the starch properties measured. The results indicate that a range of genetic and environmental variability exists for these traits in sorghum genotypes although the latter could be greater than varietal effects. Hybrid DC-75 largely differed in starch amylose content, pasting PV, and gel hardness from the local landrace varieties. Environments used for local landrace varieties caused significant differences in starch properties, hence selection and monitoring of growing conditions is essential if a particular genotype is to maintain minimum variation in the desired pasting, textural or thermal properties. Genotype×environment interactions indicate that in breeding programmes, selection for starch properties at a single location would be misleading.     

两种灌水条件下4种氮源对小麦籽粒淀粉含量及其特性的影响

为明确不同水分条件下氮源类型对小麦籽粒淀粉含量及其特性的影响,以郑麦366(强筋)和百农207(中筋)两个小麦品种为试验材料,分别在全生育期不灌水和灌拔节期+抽穗期2水条件下,研究了4种氮源(硝酸钙、硝酸铵钙、尿素和氯化铵)对小麦籽粒淀粉含量及其特性的影响。结果表明,灌2水条件下,小麦籽粒总淀粉含量、淀粉糊化特性及小淀粉粒占比均高于不灌水处理。灌水和氮源类型对淀粉含量、糊化特性及淀粉粒度分布有交互作用。在不灌水条件下,施用尿素籽粒淀粉含量和支链淀粉含量较高。在灌2水条件下,百农207以硝酸钙处理的淀粉峰值粘度、小淀粉粒表面积和体积占比最高;而郑麦366淀粉峰值粘度和小淀粉粒数量则分别以施用硝酸钙和硝酸铵钙最高。郑麦366在两种水分条件下均以施用硝酸铵钙淀粉失水率最低。品种对水分和氮肥类型的响应存在差异,总体而言,灌2水条件下,施用硝酸钙有利于淀粉糊化特性的改善;不灌水条件下,施用尿素有利于淀粉含量和支/直比提高。     

颗粒结合型淀粉合成酶研究进展

本文综述了小麦胚乳中合成直链淀粉的关键酶——颗粒结合型淀粉合成酶(GBSS)的研究进展，展望了GBSS的研究前景。小麦中的GBSS基因在种子中特异表达；控制3个Waxy，位点的基因Wx—A1、Wx—B1和Wx—D1，分别位于7AS、4AL和7DS上；六倍体小麦和二倍体小麦中3个GBSS的DNA序列从起始密码子到终止密码子，Wx—A1为2781bp，Wx-B1为2794bp，Wx—D1为2862bp。基因的完全编码区含有11个外显子和10个内含子，在核苷酸序列上三个糯基因彼此之间有惊人的同源性；研究表明，直链淀粉含量和淀粉糊化特性受Wx—B1的影响最大，其次是Wx-D1缺失蛋白，Wx-A1缺失蛋白的影响最小。GBSS的鉴定技术包括I2—KI染色、电泳和分子标记技术鉴定。     

Inheritance of flour paste viscosity is associated with a rice Waxy gene exon 10 SNP marker

Apparent amylose content is a key element for characterizing a rice (Oryza sativa L.) cultivar for cooking quality. However, cultivars with similar apparent amylose content can have widely varying quality attributes, including major parameters of flour paste viscosity. It has been postulated that the presence of a rice Waxy gene single nucleotide polymorphism (SNP) marker is associated with elevated Rapid Visco Analyser (RVA) properties in specific high amylose rice cultivars. A mapping population derived from a cross between two varieties, Cocodrie and Dixiebelle, having similar high apparent amylose contents, but with different paste viscosity properties and Waxy gene markers was analyzed for the genetic segregation of various pasting properties, measured with RVA instrumentation. Marker inheritance analyses revealed that the Waxy exon 10 SNP marker was associated with the proportion of soluble to insoluble apparent amylose and most RVA pasting measurements. Waxy gene markers can be used to efficiently improve the selection of rice with desirable characteristics, particularly for superior parboiling and canning quality.     

Effect of process conditions and amylose/amylopectin ratio on the pasting behavior of maize starch: A modeling approach

The effects of different process conditions on the pasting behavior of the 14%, w/w suspensions of high amylose, waxy and normal maize starches at mixing speeds of 50, 160 and 250 rpm with the heating rates of 2.5, 5 and 10 °C/min were investigated. In addition, the impact of the starch mixture with an amylose-amylopectin ratio of 0–70% at 160 rpm and a heating rate of 5 °C/min on the pasting parameters was studied. According to the results, when stirring speed decreased from 250 rpm to 50 rpm, the peak viscosity dramatically increased. Furthermore, both heating and stirring rates significantly affected the pasting properties (p < 0.05). The amylose content of maize starch had a negative correlation with peak viscosity, trough viscosity, breakdown viscosity, final viscosity, and setback viscosity. Besides, syneresis values decreased as amylose content decreased from 70% to 0%. According to the kinetic modelling of pasting curves, starch coefficients were found to be higher than 1 for all starches, indicating that the penetration of water into starch granules increased granule swelling rate. The findings of the present study confirmed that both process conditions and amylose/amylopectin ratio can be optimized without necessity of starch modification to obtain the products with the desired quality.     

Effects of two novel Wx-A1 alleles of common wheat (Triticum aestivum L.) on amylose and starch properties

Common wheat (Triticum aestivum L.) has three Wx proteins (Wx-A1, Wx-B1, and Wx-D1), which are granule-bound starch synthases I and are responsible for the amylose synthesis of flour starch. The effects of two novel Wx-A1 proteins identified by gel electrophoresis on amylose content and starch properties were analyzed. The variant Wx-A1 protein coded by the Wx-A1i allele was present in smaller amounts and produced less amylose (7.3%) compared to standard lines with the Wx-A1a allele (21.5%). Wx-A1i generated altered starch properties; greater swelling power (SP), glucoamylase digestibility, starch paste clarity, and gelatinization enthalpy in differential scanning calorimetry. The starch from Wx-A1i also showed an altered pasting profile on a Rapid Visco-Analyzer, greater peak viscosity, smaller final viscosity, and lower pasting temperature. The Wx-A1i allele is a novel genetic resource for reducing amylose content in wheat. The other Wx-A1 protein coded by the Wx-A1j allele showed a more basic isoelectric point compared to Wx-A1a on an electrophoretic gel. The amylose content of Wx-A1j did not differ from standard Wx-A1a. Starch SP, paste clarity, and glucoamylase digestibility also suggested that Wx-A1j produced amylose as much as Wx-A1a.