西藏冬青稞胚乳淀粉粒发育特征研究

为了解青稞胚乳淀粉及淀粉粒形成与生长特征,以西藏育成青稞品种冬青8号为材料,对籽粒发育过程中胚乳灌浆速度、淀粉积累量及淀粉粒的产生、二维面积、粒径变化进行了分析。结果表明,胚乳发育过程中,干物质和淀粉积累量呈S型曲线,两者呈正相关。花后5d,青稞胚乳中可零星见到粒径和二维面积较小的A型小淀粉粒;花后10~15d,A型小淀粉粒数量显著增大,但粒径和二维面积增加较慢;花后20d,B型小淀粉粒可能已经形成,与A型小淀粉粒组成一个复合群体;花后25d,形成了粒径10μm的A型淀粉粒、粒径5~10μm的B型淀粉粒和粒径5μm的C型淀粉粒;花后30~55d,不同粒径的淀粉粒数量和二维面积逐渐增加,其中,C型淀粉粒数量不断增加直至籽粒成熟。青稞成熟籽粒胚乳中,淀粉粒的粒径为1.45~44.76μm,二维面积为3.56~1 750.8μm2;A型淀粉粒形状为近圆形,表面光滑,个别表面附着有C型淀粉粒,B型淀粉粒形状有近圆形、椭圆形多种类型,C型淀粉粒形状比B型淀粉粒的变异更大。     

不同直链淀粉含量小麦品种的淀粉粒度分布特征

为研究不同类型小麦品种淀粉粒的分布特征,以直链淀粉含量(Am)不同的3组小麦品种为供试材料,分析其成熟期胚乳的淀粉粒度分布。结果表明,9个小麦品种淀粉粒粒径大小范围均为0.4~45.0μm,体积与表面积分布均呈双峰曲线,数目分布表现为单峰变化;B型淀粉粒数目占总数目的99.8%~99.9%。Am不同的3组小麦品种的A、B型淀粉粒体积百分比存在显著差异,糯小麦B型淀粉粒体积百分比最高,高Am组的最低。不同类型小麦籽粒A、B型淀粉粒的数目百分比无显著差异,说明糯小麦籽粒B型淀粉粒体积百分比升高主要是由于其个体体积较大所致。     

糯小麦籽粒淀粉粒度分布特征

为进一步加深对糯小麦淀粉特性的认识,选用2个糯小麦和2个普通非糯小麦品种为材料,利用激光粒度分析仪分析了糯小麦完熟籽粒中淀粉的粒度分布特征,及其与普通非糯小麦品种的差异。结果表明,糯小麦淀粉粒的粒径分布范围为1.0~43.7 μm,不同粒径淀粉粒的数目比例分布呈单峰曲线变化,体积和表面积分布均呈双峰曲线变化;糯小麦籽粒中存在2种类型淀粉粒,即A型大淀粉粒（直径≥10 μm）和B型小淀粉粒（直径<10 μm）,B型淀粉粒的数目、体积和表面积比例均高于A型淀粉粒。与普通非糯小麦相比,糯小麦籽粒中B型小淀粉粒的数目、体积和表面积比例较高,淀粉粒的平均粒径和中位粒径较大。糯小麦与普通非糯小麦不同粒径淀粉粒的数目、体积和表面积比例分布曲线存在差异。糯小麦B型淀粉粒处的峰高显著高于普通非糯小麦,A型淀粉粒处的峰值低于后者。糯小麦体积和表面积分布中B型淀粉的峰值粒径显著小于普通非糯小麦。     

稻茬晚播小麦胚乳淀粉粒度分布的粒位差异

为研究稻茬晚播小麦胚乳淀粉粒分布的粒位差异,以小麦品种山农1391和藁城8901为材料,设适期播种和晚播2种播期处理,研究小麦强势、弱势籽粒胚乳淀粉粒粒度分布特征。结果表明,小麦强、弱势籽粒中均具有A、B型淀粉粒,但淀粉粒的分布因不同处理具有显著差异。不同小麦品种、播期和粒位下,淀粉粒的体积分布均呈双峰分布,峰值分别为4.878~6.453μm和21.7~23.82μm;淀粉粒数目分布呈单峰分布,峰值为0.520~0.571μm。藁城8901的B型淀粉粒的体积、数目、表面积占比均显著高于山农1391;山农1391的A型淀粉粒的体积、数目、表面积百分比显著高于藁城8901。晚播处理使小麦B型淀粉粒占比显著升高,A型淀粉粒占比显著降低;弱势粒中B型淀粉粒占比降低,A型淀粉粒占比显著上升。晚播处理对山农1391的影响大于藁城8901。     

灌浆期遮阴对小麦胚乳淀粉粒度分布及糊化特性的影响

为了解灌浆期遮阴对小麦胚乳淀粉粒度分布及淀粉糊化特性的影响,研究了灌浆期对扬麦13、宁麦13和烟农19进行30%遮阴后籽粒的淀粉粒度分布与糊化特性的变化。结果表明,小麦灌浆期遮阴显著降低了<10μm的B型淀粉粒体积和表面积占比,增加了>10μm的A型淀粉粒的体积和表面积占比,其中A型淀粉粒中主要增加了10~20μm淀粉粒的体积和表面积占比;遮阴处理对淀粉粒数目分布无显著影响。遮阴处理后,峰值粘度、低谷粘度、稀懈值、最终粘度、回升值等糊化参数指标均显著降低。小麦籽粒硬度、容重、出粉率等指标也因遮阴处理而显著降低。综上所述,遮阴处理改变了小麦籽粒淀粉粒粒度分布,降低了淀粉糊化参数和加工品质。     

花后干旱对小麦胚乳淀粉粒发育和理化特性的影响

我国小麦主产区在籽粒灌浆期往往频发干旱,常导致小麦产量下降和品质变劣。为了解花后干旱对小麦籽粒淀粉粒发育及淀粉理化特性的影响,以中强筋小麦新冬20号和新冬23号为供试材料,在花后干旱胁迫下对小麦籽粒灌浆过程中淀粉粒形态、粒径、淀粉降解酶活性以及淀粉相对结晶度、持水力、膨胀势、溶解度和破损淀粉粒含量进行了研究。结果表明,花后干旱处理下两个参试小麦品种的淀粉粒基本形态未发生明显变化。对比新冬20号,花后干旱对新冬23号淀粉粒的形成、发育影响更大。花后干旱处理下,新冬20号和新冬23号胚乳中的淀粉降解酶活性均在灌浆后期达到峰值,花后35 d时,籽粒淀粉降解酶活性均明显高于同时期的对照。花后干旱未改变参试小麦品种淀粉粒的结晶类型,但降低了其相对结晶度。花后干旱处理的新冬23号籽粒中淀粉粒的持水力和破损淀粉含量显著低于对照。试验说明花后干旱胁迫影响了小麦籽粒灌浆过程中淀粉降解酶活性,进而作用于淀粉粒的表观结构,最终对淀粉粒的理化特性产生影响,影响程度与参试小麦品种的遗传特性有关,干旱敏感型品种受其影响更为明显。     

紫糯小麦籽粒石蜡切片制作技术优化及淀粉粒累积分析

为了探明糯性小麦授粉后籽粒淀粉粒的累积情况,以山农紫糯2号授粉后不同天数的籽粒为试验材料,通过对传统石蜡切片技术的脱水、透明和浸蜡等环节进行改进,制作切片后对小麦籽粒结构发育进行观察研究。结果显示,与传统石蜡切片方法相比较,技术改良70%乙醇和无水乙醇脱水时间与逐级透明和渐进式浸蜡环节后,小麦籽粒（授粉后0~14 d）不皱缩变形,石蜡切片完整,且染色分明,结构显示清晰。授粉后0~2 d,果皮中已经开始积累少量淀粉粒,随着授粉后天数推移而逐渐增多;授粉后第6天,胚乳内部逐渐由游离核期向细胞化过渡;授粉后第8天,胚乳细胞进一步增大,淀粉粒开始累积,但体积较小;授粉后第10~12天,胚乳细胞向无核化发展,不同部位胚乳细胞和淀粉粒的排列分布呈现明显差异;授粉后第14天,胚乳细胞中几乎完全充满淀粉粒。表明改进的石蜡切片制作方法适合于早期小麦籽粒的结构研究。     

专用小麦胚乳背部和腹部淀粉粒发育的差异

为从微观角度了解小麦胚乳淀粉体的发生和发展过程,以强筋小麦徐麦30、中筋小麦扬麦11和弱筋小麦扬麦13为材料,利用显微技术研究了小麦胚乳背部和腹部淀粉粒的大小、数量和发育等特性。结果表明：（1）小麦胚乳淀粉粒粒径在颖果发育前期增加速率较快,而在发育后期增加较慢。同一品种腹部大淀粉粒粒径长度高于背部。品种间大淀粉粒粒径表现为扬麦13>扬麦11>徐麦30,小淀粉粒径表现为扬麦13>徐麦30>扬麦11。（2）在小麦胚乳发育过程中单位面积大淀粉粒的数量呈现先降后升的变化趋势。小麦胚乳大淀粉粒数量表现为徐麦30>扬麦11>扬麦13。胚乳细胞中小淀粉粒数量呈现持续增加的趋势,前期增加速率较快,后期较慢,品种间大小淀粉粒总数量均表现为扬麦13>扬麦11>徐麦30。（3）不同专用小麦成熟籽粒背部和腹部淀粉粒的形态及分布存在差异。同一品种腹部大淀粉粒数量较多,小淀粉粒数量较少,而背部小淀粉粒数量较多,大淀粉数目较少。三种专用小麦相比,弱筋小麦扬麦13小淀粉粒的数量最多,且排列疏松;而强筋小麦徐麦30小淀粉粒数量较少,且与蛋白体紧密结合,质地致密;中筋小麦扬麦11介于两者之间。     

孕穗期施氮对小麦蛋白质组分积累和蛋白质体发育的影响

为了揭示氮素对小麦蛋白质品质的调节效应,以扬麦9号为材料,研究了孕穗期施氮对小麦籽粒蛋白质组分积累及胚乳细胞蛋白质体发育的影响.结果表明:(1)随花后天数的增加,小麦籽粒清蛋白含量呈现由高到低的变化,球蛋白含量先下降,后期又升高;而醇溶蛋白和麦谷蛋白含量基本呈现由低到高的变化;(2)孕穗期施氮能显著提高醇溶蛋白和麦谷蛋白含量,而对清蛋白和球蛋白含量影响较小;(3)小麦胚乳细胞中蛋白质体约在花后12 d出现,花后16 d蛋白质体开始大量合成,其数目迅速增多,体积变大.成熟后期,蛋白质体因胚乳细胞中大小淀粉体的充实被挤成片层结构而填充在淀粉体缝隙中.胚乳边缘细胞中蛋白质体大而多,中部细胞蛋白质体小而少;(4)孕穗期施氮可促进蛋白质体的形成,使其数目增多.     

小麦胚乳发育过程中贮藏蛋白的积累和蛋白体的形成

为给小麦品质育种提供参考,采用光学和电子显微镜技术系统观察了小麦品种扬麦12号胚乳发育过程中贮藏蛋白的积累和蛋白体的形成.结果表明,花后8 d的淀粉胚乳细胞开始出现贮藏蛋白颗粒.贮藏蛋白在粗内质网上合成后,有些经过高尔基体形成浓密小泡,有些直接在粗内质网腔中积累,脱离内质网形成蛋白体;浓密小泡和蛋白体进入蛋白贮藏液泡(PSV).早期的蛋白体较小,呈球状;随着胚乳发育,蛋白体可以相互融合,扩大体积.后期的蛋白体相互融合形成蛋白质基质,单个蛋白体不再存在;接近成熟期的胚乳,胚乳细胞被贮藏物质淀粉粒和蛋白质基质所充实,蛋白质基质分布在淀粉粒之间的空隙内.试验结果说明,贮藏蛋白从内质网到PSV的转运有两种途径:依赖高尔基体途径和内质网衍生出蛋白体途径.     

小麦胚乳A、B型淀粉粒分离纯化方法研究

为了能够准确研究小麦籽粒胚乳中A、B型淀粉粒的形成机理、化学组分及理化特性,对前人分离提纯A、B型淀粉粒的方法进行改进,提出了适于小麦A、B型淀粉粒分离提纯的常量法和微量法。用4个不同淀粉含量类型的小麦品种籽粒对此方法进行验证,结果表明4个品种A、B型淀粉粒在常量法中的分离纯度分别达到79.46%~85.23%和90.27%~96.43%,在微量法中的分离纯度分别达到92.68%~96.70%和96.48%~99.00%。在常量法和微量法中,A型淀粉粒的分离纯度与品种淀粉含量成正相关, B型淀粉粒分离纯度与品种淀粉含量成负相关;而A、B型淀粉粒在两种方法中的分离产率与品种淀粉含量没有显著关系。     

Pre-anthesis high temperature acclimation alleviates the negative effects of post-anthesis heat stress on stem stored carbohydrates remobilization and grain starch accumulation in wheat

The potential role of pre-anthesis high temperature acclimation in alleviating the negative effects of post-anthesis heat stress on stem stored carbohydrate remobilization and grain starch accumulation in wheat was investigated. The treatments included no heat-stress (CC), heat stress at pre-anthesis only (HC), heat at post-anthesis only (CH), and heat stress at both stages (HH). Post-anthesis heat stress decreased grain starch content, reduced the content of fructans and depressed activities of related synthesis enzymes of sucrose:sucrose fructosyltransferase and fructan:fructan fructosyltransferase. Interestingly, HH plants had significantly higher grain yield than the CH plants. In addition, post-anthesis high temperature lowered grain starch content and increased percentages of volume, number and surface area of B-type starch granules in CH and HH than in CC treatment. However, HH plants had much higher starch content, and caused less modified B-type starch granule size indicators than the CH plants. Our results indicated that, compared with the non-acclimated plants, the pre-anthesis high temperature acclimation effectively enhanced carbohydrate remobilization from stems to grains, led to less changed starch content and starch granule size distribution in grains of wheat under post-anthesis heat stress.     

Influence of environmental temperature during grain filling period on granule size distribution of rice starch and its relation to gelatinization properties

High temperature (HT) is the major environmental factor affecting grain starch properties of cooking rice cultivars. However, little information has been available on the effect of environmental temperature on the starch granule size distribution of rice grains. In this paper, five indica rice genotypes, including the wild type (9311) and its four mutants differing in amylose content (AC), were used to investigate the effect of environmental temperature on the starch granule size distribution, as well as its relation to AC and gelatinization properties of rice starch. Two temperature treatments (HT and NT) at filling stage were imposed to rice plants under the controlled temperature chambers. The result showed that HT increased the average diameter of starch granules and enhanced the proportion of large starch granules (LSG, D > 2.6 μm) by number, volume and surface area, respectively. However, influence of HT on GT and starch granule size distribution was relatively independent of their alteration in AC level for different rice genotypes. Therefore, HT-induced increase in the average diameter of starch granules and LSG percentage was strongly responsible for the higher starch gelatinization temperature and inferior cooked palatability of HT-ripening rice grains, which be not inherently associated with their varying AC level.     

施氮水平对小麦籽粒淀粉粒分布与加工品质的影响

为明确施氮对小麦淀粉粒分布与加工品质的影响,选用强筋小麦藁城8901和弱筋小麦豫麦50为材料,分析了不同施氮水平下小麦籽粒淀粉粒分布特征与部分加工品质指标。结果表明,适量施氮(240kg.hm-2)显著提高籽粒B型淀粉粒体积百分比,过量施氮(360kg.hm-2)时小麦籽粒B型淀粉粒体积百分比降低。施氮水平对两个小麦品种籽粒A、B型淀粉粒数目百分比无显著影响。在施氮0～240kg.hm-2范围内,增施氮肥可以提高籽粒直、支链淀粉积累量,而过量施氮不利于籽粒直、支链淀粉的积累。小麦湿面筋、沉淀值、面团形成时间和稳定时间等参数与A型淀粉粒体积百分比呈显著负相关,与B型淀粉粒体积百分比呈显著正相关。适量施氮能使强筋小麦加工品质变优;增施氮肥导致弱筋小麦加工品质变劣。     

Starch granule morphology in oat endosperm

Mature and developing oat (Avena sativa) grains were sectioned and image analysis methods used to estimate the starch granule-size distribution and morphology in endosperm cells. This showed that oat endosperm cells contain two types of starch granule: compound starch granules such as those seen in rice endosperm and in most other grasses; and simple granules similar to the B-type starch granules seen in the endosperm of Triticeae species such as wheat (Triticum aestivum). The simple granules in oats are similar in size and relative abundance to B-type granules in Triticeae suggesting that they may share a common evolutionary origin. However, there is a fundamental difference between oats and Triticeae in the timing of granule initiation during grain development. In Triticeae, the B-type granules initiate several days after the A-type granules whereas in oats, both the simple and compound granule types initiate at the same time, in early grain development.     

Effect of heating temperature on the particle size distribution in waxy wheat flour

The particle size of waxy (amylose-reduced) wheat (Triticum aestivum L.) starch was determined at isothermal temperatures by laser diffraction analysis. Flour samples were suspended in deionized water at temperatures ranging from 30 to 90 °C for 20–60 min. At 30 °C, all of the flour particles exhibited trimodal size distributions, i.e., the particles in the first, second, and third modes were <10 μm, 10–50 μm, and 51–300 μm, respectively. Control experiments with isolated starch indicated that the first and second modes were associated mainly with starch granules, whereas the third mode may have been related to gluten and gluten adhesion. The particle size distributions of waxy segregant wheat flours were temperature dependent. At 60 °C, there were significant changes in the particle size and distribution of waxy flours, which indicated the swelling of starch granules in response to elevated temperature. As the temperature increased, the peak particle size of waxy segregant wheat flours increased in different ways. The results suggest that variations in the swelling properties of selected waxy genotype flours may be due to the strength of starch–protein interaction and the capacity for starch granule gelatinization.