Molecular Basis of the Gelatinisation and Swelling Characteristics of Waxy Rice Starches Grown in the Same Location During the Same Season

Six waxy rice samples (grown at the same site during the same season) were investigated to identify those aspects of amylopectin structure and granule composition which differentiate the starches into high (T_p 77·8 °C on average) or low (T_p 66·2 °C on average) gelatinisation temperature. All starches contained less than 2·5% amylose with negligible lipid. Granule dimensions were similar (mean diameter 4·9–5·7 μm) as was the β-amylolysis limit (59·9–63·0%). However, the structural elements of amylopectins within the two groups varied. The low gelatinisation temperature starches contained two major chain fractions upon debranching with iso-amylase, F3 (DP 16) and F1 (DP 51) on average while the high gelatinisation temperature starches contained three fractions, F3 (DP 16), F2 (DP 19) and F1 (DP 40). The proportion of F1/(F2+F3) for the low and high gelatinisation starches representing on average 20·2 and 10·5% respectively. Hence, the higher proportion of exterior chains and especially those with DP 19 appear to confer the higher gelatinisation temperature characteristic of these starches. Debranched β-limit dextrins were prepared from these starches. Regardless of their origin, (high or low gelatinisation temperature), they contained three fractions: F_3β (DP 5), F_2β (DP 13) and F_1β (DP 19). Hence, the high versus low gelatinisation characteristic was imparted by the exterior chains. Using 13-C CP-MAS/NMR it was confirmed that the number of double helices within the starches were approximately constant although small differences in crystallinity were identified by X-ray diffraction. Retrogradation of the solubilised native high and low gelatinisation temperature amylopectin molecules confirmed that the ‘high temperature gelatinisation amylopectin’ molecules form higher dissociation temperature and enthalpy crystalline domains. This confirms that the higher proportion of short and especially relatively longer short chains promotes crystallite formation.     

Effects of Weak Light on Starch Accumulation and Starch Synthesis Enzyme Activities in Rice at the Grain Filling Stage

Photosynthetic product in rice plant is transported to grains mainly in the form of sucrose. Sucrose in the grains eventually becomes starch through a series of enzymatic reactions [1-2]. The starch weight accounts for 90% of the brown rice [3-4], so the course of the rice grain filling is the biochemical process in which starch is mainly formed, and the factor of light is indispensable at the course. Much research has been conducted to study the influence of the light on the grain starch synt…     

富含抗性淀粉水稻突变体的淀粉特性

 从杂交水稻优异恢复系R7954诱变筛选了1个富含抗性淀粉的突变体RS111。该突变体热米饭中抗性淀粉的含量高达7.0%，是其野生型的2.4倍。突变体的淀粉颗粒形态、DSC和多晶衍射的曲线和参数与野生型明显不同，表现为淀粉颗粒大小较为一致，圆形和卵形淀粉颗粒所占比率较高，溶晶起始温度(TO)、最高温度(TP)、回落温度(TC)、焓变(ΔHGEL)及结晶度更低。突变体的表观直链淀粉、粗脂肪和粗纤维的含量显著提高。     

Starch Digestibility and Functional Properties of Rice Starch Subjected to Gamma Radiation

This study investigated the effect of gamma radiation on the digestibility and functional properties of rice starch. Rice cultivars IRGA417 and IAC202 were used for isolation of starch by the alkaline method. Starch samples were irradiated with 1, 2 and 5 kGy doses of ⁶⁰Co at a rate of 0.4 kGy/h. A control sample, which was not irradiated, was used for comparison. Irradiated and control starches were characterized by in vitro starch digestibility, total dietary fiber, color, water absorption index, water solubility index, syneresis, swelling factor, amylose leaching, pasting properties and gel firmness. Irradiations changed starch digestibility differently in either cultivar. Increasing radiation doses promoted increase in the color parameter b* (yellow), elevation in the capacity to absorb water, and solubility in water as well as the amylose leached from granules for both cultivars. Pasting properties showed a decrease that was proportional to the dose applied, caused by the depolymerization of starch molecules. Gel firmness of the starch from IAC202 was inversely proportional to the radiation dose applied, whereas for IRGA417, there was a reduction at 5 kGy dose. Rice starches can be modified by irradiation to exhibit different functional characteristics and they can be used by the food industries in products such as soups, desserts, flans, puddings and others.     

Relationship Between Degree of Starch Gelatinization and Quality Attributes of Parboiled Rice During Steaming

Paddy rice samples were parboiled by soaking at 65 °C for 180 min and steaming at 96 °C for 2–10 min, and then dried to achieve the final moisture content of 11% ± 1%. The degree of starch gelatinization(DSG) and several quality attributes(head rice yield(HRY), color value and hardness) of parboiled rice were measured. Results showed that DSG(46.8%–77.9%), color value(18.08–19.04) and hardness(118.6–219.2 N) all increased following steaming. In contrast, the HRY increased(64.8%–67.1%) for steaming times between 2–4 min but decreased(67.1%–65.0%) for steaming times between 4–10 min. Linear relations between DSG and color value(R~2 = 0.87), and DSG and hardness(R~2 = 0.88) were observed. The suitable DSG of parboiled rice leading to the highest HRY was found to be 62.5%, obtained following 4 min of steaming.     

早籼稻垩白形成中胚乳淀粉粒发育的电镜观察

对不同垩白度早籼品种中优早3号（少垩白）和泸红早1号（多垩白）的不同温度处理下的胚乳淀粉粒进行了扫描电镜观察,结果显示胚乳腹部淀粉粒形成的发育过程明显受温度条件的影响。在灌浆初始,高温促使淀粉粒发育进程提前,淀粉粒形状呈圆球形,边缘光滑,从而造成成熟时淀粉粒间的空隙明显,结构疏松,垩白率高。这在少垩白品种中优早3号中表现得尤为显著。     

Effects of Early- and Late-Sowing on Starch Accumulation and Associated Enzyme Activities During Grain Filling Stage in Rice

The environmental temperature occurring during the grain filling stage is an important factoraffecting starch synthesis and accumulation in rice. We investigated starch accumulation, amylaseactivity and starch granule size distribution in two low-amylose japonica rice varieties, Nanjing 9108 andFujing 1606, grown in the field at different filling temperatures by manipulating sowing date. The two ricevarieties exhibited similar performances between two sowing dates. Total starch, amylose andamylopectin contents were lower at the early-filling stage of T1 treatment (Early-sowing) compared withthose at the same stage in T2 treatment (Late-sowing). In contrast, at the late-filling stage, when fieldtemperatures were generally decreasing, total starch and amylopectin contents in T1 were highercompared to those in T2. The ideal temperature for strong activity of ADP-glucose pyrophosphorylaseand soluble starch synthase was about 22℃. A higher temperature from the heading to maturity stagesin T1 increased the activities of starch branching enzyme and suppressed the activities of granule boundstarch synthetase and starch debranching enzyme. We found that rice produced larger-sized starchgranules under the T1 treatment. These results suggested that due to the early-sowing date, the hightemperature (30℃) occurring at the early-filling stage hindered starch synthesis and accumulation,however, the lower temperatures (22 ℃) at the late-filling stage allowed starch synthesis and accumulationto return to normal levels.     

水稻灌浆过程中籽粒淀粉合成关键酶活性与蒸煮食味品质

选用稻米蒸煮食味品质有显著差异的4个粳稻品种,对水稻籽粒灌浆过程中淀粉合成关键酶的活性变化及其与蒸煮食味品质关系进行了研究。 不同品质类型的品种间籽粒直链淀粉和支链淀粉含量在灌浆前、中后期表现出差异,这种差异主要表现在灌浆不同时期淀粉积累速率上。籽粒灌浆过程中,不同品质类型的品种中ADPG焦磷酸化酶和可溶性淀粉合成酶活性出现峰值的时间无差异,但淀粉分支酶活性出现峰值的时间,劣质品种明显早于优质品种,而且优质品种灌浆中、后期仍然保持较高水平的酶活性。ADPG焦磷酸化酶、可溶性淀粉合成酶、淀粉分支酶的活性与直链淀粉含量、支链淀粉含量、味度值、RVA谱特性间的相关性和程度因灌浆时期不同而发生变化。在整个灌浆过程中,可溶性淀粉合成酶活性与味度值间的相关均不显著,但灌浆前期和中、后期的ADPG焦磷酸化酶和淀粉分支酶的活性与味度值间呈显著或极显著相关。选择灌浆前期酶活性低或灌浆后期酶活性高的材料,将有利于提高稻米蒸煮食味品质。     

Physiochemical Properties of Resistant Starch and Its Enhancement Approaches in Rice

With changes in food preferences and life styles,more and more attentions have been focused on healthier food.Nowadays,resistant starch(RS)which can resist digestion in the human intestine has been recognized and accepted.High RS diet shows great benefit for the human health,and breeding high RS rice variety is a great target for realizing dietary intervention.To provide guidance for RS improvement in rice,this review summarized the unique physiochemical properties of RS and the possible approaches,i.e.genetic regulation,for enhancing RS content in rice,and proposed the potential ways to obtain rice variety with high RS content.     

稻谷碎米淀粉性能改良研究初报

试验采用6种不同处理方法对碎米淀粉性能改良作了初步的探讨和研究,结果表明:碎米放置在温度42℃、湿度88%的老化箱内进行人工加速老化11d后,胶稠度由原来的44.67mm下降为33.33mm,胶稠度显著降低,但该方法是否适用于米粉加工还有待在生产实践中进一步验证。     

灌浆结实期弱光对水稻籽粒淀粉积累及相关酶活性的影响

 选用IR72（籼稻）和日本晴（粳稻）为材料，在开花后进行遮光处理，对弱光条件下籽粒淀粉和直链淀粉含量的动态变化及相关酶的活性进行了研究。在弱光条件下，两品种籽粒的淀粉含量减少，直链淀粉含量下降，蔗糖含量降低，ADPG焦磷酸化酶活性的变化较小，可溶性淀粉合成酶和颗粒结合型淀粉合成酶活性减弱，可溶性淀粉分支酶Q酶和颗粒结合型淀粉分支酶活性增强，淀粉去分支酶活性因品种而异，IR72表现为减弱，日本晴则为增强。相关分析表明，遮光下蔗糖输入量的减少量和淀粉合成量的下降量呈显著正相关；ADPG焦磷酸化酶和淀粉分支酶活性与淀粉积累速率呈显著正相关。分析指出，遮光下淀粉合成酶活性的降低与淀粉合成量的下降有关，淀粉分支酶活性的升高是直链淀粉占淀粉总量的比率减少的重要原因。     

水稻弱势籽粒淀粉形成对稻米品质影响研究进展

随着社会的发展和经济水平的提高,人们的消费习惯和消费结构发生了巨大变化,人们对优质稻米的需求越来越高,有关稻米品质的研究也越发得到重视。本文综述了影响水稻弱势籽粒淀粉品质形成的机理与相应调控途径,基于此,提出了通过调控水稻弱势籽粒淀粉形成来提高稻米整体营养品质的新思路。     

OsESV1基因对水稻淀粉合成的影响

【目的】 研究水稻EARLY STARVATION1 (OsESV1)基因对水稻淀粉代谢的影响。【方法】 通过CRISPR-Cas9技术获得osesv1突变体,考查osesv1的表型及胚乳淀粉的理化特性,分析OsESV1的表达特性及相关功能。【结果】 OsESV1蛋白在植物界中十分保守。osesv1突变体株高、穗长、每穗粒数低于野生型,分蘖数显著多于野生型,叶片中淀粉含量显著下降,籽粒中的直链淀粉含量上升,而总淀粉含量无明显变化。OsESV1呈组成型表达,并且具有昼夜节律表达的特征。OsESV1蛋白定位在叶绿体内且呈点状分布。酵母双杂交和双分子荧光互补实验结果表明OsESV1蛋白可以与ADP-葡萄糖焦磷酸化酶小亚基(OsAGPS) 2a和OsAGPS1互作。【结论】 OsESV1基因影响水稻叶片的淀粉合成途径,而对胚乳淀粉合成的影响不明显。     

结实期低温胁迫对水稻强、弱势粒淀粉形成与积累的影响

【目的】研究结实期低温胁迫对水稻强、弱势粒淀粉组分含量、积累速率及关键酶活性的影响，明确淀粉合成关键酶活性变化对淀粉积累速率的调控效应，探究强、弱势粒淀粉形成积累差异对水稻产量的影响。【方法】以耐冷型品种东农428和冷敏型品种松粳10为试验材料，设置1个常温处理(白天温度28℃，14h/夜间温度22℃，10 h，7 d)和4个低温处理(17℃，低温处理时间分别为1、3、5、7 d)，分析了结实期低温胁迫对强、弱势粒淀粉组分积累、合成关键酶活性、水稻产量及构成因素的影响，并探讨了灌浆期各阶段淀粉积累差异与酶活性变化的关系。【结果】与对照相比，结实期低温胁迫降低了两个品种水稻强、弱势粒中腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)、可溶性淀粉合成酶(SSS)、淀粉分支酶(SBE)的峰值活性以及支链淀粉和总淀粉含量，提高了齐穗后28~38 d 低温处理3、5、7 d的颗粒结合型淀粉合成酶(GBSS)活性和直链淀粉含量。与对照相比，各低温处理酶活性最高和淀粉积累最快的时间均有不同程度的推迟，低温处理7 d的影响最大，强、弱势粒低温处理7 d的支链淀粉和总淀粉含量分别在齐穗后13、18 d降幅最大，直链淀粉含量在28 d增幅最大。相关分析表明，强、弱势粒直链淀粉含量及强势粒支链淀粉、总淀粉含量与其最大积累速率呈极显著正相关，弱势粒支链淀粉、总淀粉含量还受到其最大积累速率出现时间的影响。AGPase、GBSS、SSS、SBE活性变化与淀粉积累速率和积累时间早晚密切相关，对淀粉及淀粉组分含量的变化有着明显的影响。同时，结实期低温胁迫显著降低了水稻的千粒重、结实率和产量，且随低温处理天数的增加降幅逐渐增大。结实期低温胁迫对弱势粒中淀粉合成关键酶活性变化影响大于强势粒，弱势粒淀粉合成积累减慢，含量降低，导致水稻千粒重显著下降，产量降低。【结论】就品种而言，耐冷型东农428具有较高的淀粉合成关键酶活性，淀粉及其组分含量较高，在低温胁迫下产量能维持在较高的水平。因此，强、弱势粒淀粉合成关键酶活性对淀粉合成起着非常关键的调控作用，淀粉组分和含量及其变化对产量有着十分重要的影响。     

水稻品种Basmati 370和Koshihikari 抗性淀粉颗粒RS2的研究

 以一个优质籼稻品种 Basmati 370 和一个优质粳稻品种 Koshihikari （越光）为材料,研究了抗性淀粉颗粒RS2的来源和链长分布情况。结果表明,两个品种RS2的主要来源均为直链淀粉,体积排阻色谱SEC的分析结果表明这部分直链淀粉不仅包括真正的直链淀粉,还包括了带分支的直链淀粉和带长分支链的支链淀粉。对抗性淀粉颗粒RS2的支链链长分析表明,2个品种长链(聚合度＞36)所占的比例均大于26%。     

水稻胚乳淀粉合成相关酶的结构、功能及其互作研究进展

淀粉作为稻米最主要的储藏物质,其生物合成过程直接影响水稻的产量和品质。水稻淀粉的生物合成在造粉体中通过一系列酶促反应完成。本文综述了淀粉合成过程中ADP-葡萄糖焦磷酸化酶(AGPase)、淀粉合酶(SSs)、淀粉分支酶(BE)及淀粉脱支酶(DBE)的结构、功能以及各酶之间的相互作用的最新研究进展,以期为稻米品质改良提供理论参考依据。     

水稻灌浆过程中胚乳异淀粉酶基因家族表达特性及其与淀粉含量间关系分析

选用胚乳直链淀粉和支链淀粉含量不同的5个粳稻品种,分析籽粒灌浆过程中异淀粉酶基因在胚乳中的表达特性和酶活性变化及其与淀粉含量间的关系。结果表明,在灌浆过程中胚乳异淀粉酶活性及ISA1和ISA3基因的mRNA表达量,直链淀粉含量不同的非糯品种都呈先升后降的单峰曲线变化。灌浆中期出现峰值,但糯稻品种呈直线上升的变化趋势,后期的表达量明显高于前期;ISA2基因mRNA表达量自抽穗后10 d起随灌浆进程逐渐下降;在灌浆过程中胚乳ISAs基因的mRNA表达量与异淀粉酶活性正相关;ISA1和ISA3基因mRNA表达量、异淀粉酶活性及支链淀粉含量呈同步变化。在整个灌浆过程中ISA1基因和ISA1和ISA3基因的表达量明显大于ISA2基因,是灌浆过程中主要表达的基因。     

高抗性淀粉水稻新品种优糖稻2号的选育及其特征特性

优糖稻2号系由上海市农业科学院作物育种栽培研究所利用系谱法选育而成的一个富含抗性淀粉的功能水稻新品种,2019年通过上海市农作物品种审定委员会审定。优糖稻2号抗性淀粉含量高达13.1%。抗性淀粉是在健康者小肠中不被吸收的淀粉及其降解产物的总称,具有控制血糖、预防肠道疾病、控制体质量、促进维生素和矿物质吸收等重要的生理功能。本文介绍了优糖稻2号的选育经过、产量表现、主要特征特性及栽培技术要点。     

高直链淀粉突变体Goamy2的淀粉糊化特性及淀粉结构分析

以高直链淀粉及突变体材料Goamy2及其野生型亲本Ilpumbyeo米粉为材料,比较了它们在理化性质和糊化特性上的差别,并通过体积排阻色谱(Size Exclusion Chromatography,SEC)分析其水溶性和不溶性淀粉组成结构差别。从冷水溶性成分来看,Goamy2主要以小分子DP141～DP2(DP为聚合度)为主,而Ilpumbyeo中带分支的链DP4100～DP64也就是相对大分子所占的比例较高,达到33.3%。从热水溶性淀粉成分来看,突变体Goamy2直链淀粉和支链淀粉的比例大致为4∶1,而Ilpumbyeo直链淀粉和支链淀粉比例大致为1∶1。至于两个材料的热水溶性支链淀粉链长分布,长短链比例差别较大,Goamy2长短链比率为0.67,而Ilpumbyeo为0.32。从热水不溶性成分来看,两个材料均以支链淀粉为主,直链淀粉所占的比例很低,均不到5%。热水不溶性支链成分的链长分布中,野生型亲本Ilpumbyeo以短链为主,短链所占的比例高达72.5%,而突变体Goamy2短链和长链几乎各占一半。