玉米籽粒淀粉积累及相关酶活性分析

【目的】分析玉米籽粒发育过程中灌浆速率、蔗糖代谢、淀粉积累及相关酶活性的变化,了解玉米籽粒淀粉积累的控制机理。【方法】以高淀粉玉米（费玉3号）和普通玉米（豫玉22）为材料,进行大田试验,采用比色法测定蔗糖含量,采用双波长法测定淀粉及其组分含量的变化动态,参照Douglas等的方法测定蔗糖合成酶（SS）活性,参照Nakamura等的方法测定腺苷二磷酸葡萄糖焦磷酸化酶（ADPGPPase）、束缚态淀粉合成酶（GBSS）、淀粉分支酶（SBE）和去分支酶（DBE）的活性。【结果】灌浆速率、蔗糖含量、淀粉积累速率及SS、GBSS、SBE活性的高低均存在明显的基因型差异,授粉后10 d后,费玉3号上述指标均高于豫玉22。相关性分析表明,灌浆中后期SS活性与淀粉积累速率和籽粒灌浆速率均呈（极）显著正相关;ADPGPPase、DBE活性与淀粉积累速率和籽粒灌浆速率的相关性未达到显著水平;GBSS活性与直链淀粉积累速率呈极显著正相关,与籽粒灌浆速率相关性不显著;SBE活性与支链淀粉积累速率和籽粒灌浆速率呈极显著正相关。【结论】ADPGPPase和DBE不是影响玉米籽粒中淀粉积累的关键酶;SS是淀粉积累的限速因子;GBSS对直链淀粉积累起重要的调节作用;SBE对支链淀粉积累起关键作用。     

Starch Accumulation and Enzyme Activities Associated with Starch Synthesis in Maize Kernels

The filling rate and the starch accumulation in developing maize kernel were analyzed. The changes of enzyme activities associated with sucrose metabolism and starch biosynthesis were investigated. The purpose is to discuss the enzymatic mechanisms responsible for starch synthesis. Two types of maize cultivars （Zea mays）, high starch maize （Feiyu 3） and normal maize （Yuyu 22）, were grown in a corn field. The factors involved in starch synthesis were performed during the growth period. The kernel filling rate, the sucrose content, the starch accumulating rates and the activities of SS （sucrose synthase）, GBSS （granule-bound starch synthase）, SBE （starch branching enzyme） of Feiyu 3, which has high starch content, were significantly higher than those of Yuyu 22, which has low starch content, after 10 DAP （days after pollination）. Correlation analysis indicated that ADPGPPase （ADP-glucose pyrophosphorylase） and DBE （starch debranching enzyme） were not correlated with the starch accumulating rates and the kernel filling rate, but the SS activity at the middle and late period were highly significantly correlated with the starch accumulating rates and the kernel filling rate. The GBSS activity was highly significantly correlated with the amylose accumulating rate, but not correlated with the kernel filling rate. The SBE activity was highly significantly correlated with the amylopectin accumulating rate and the kernel filling rate. It was not ADPGPPase and DBE, but SS was the rate-limiting factor of starch biosynthesis in developing maize kernels. GBSS had an important effect on amylose accumulation, and SBE had a significant effect on amylopectin accumulation.     

水稻发育胚乳中淀粉的积累及淀粉合成的酶活性变化

利用４个粒重相近品种（组合）,对胚乳发育期间蔗糖、可溶性糖的淀粉含量、籽粒灌浆速率及与淀粉合成有关的６个酶活性的变化进行了研究。结果表明,品种间及不同剪叶处理间强势粒的淀粉积累和酶活性差异较小,而弱势粒差异明显。蔗糖合成酶,ＡＤＰＧ焦磷酸化酶、可溶态淀粉合成酶、淀粉分枝酶（Ｑ酶）、活性的变化与灌浆速率曲线十分吻合,相关性极显,而ＵＤＰＧ焦磷酸化酶活性变化与灌浆速率曲线吻合性较差。结合态淀粉合成酶     

Changes in Activities of the Key Enzymes Related to Starch Synthesis in Rice Grains During Grain Filling and Their Relationships with the Filling Rate and Cooking Quality

With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase (ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during grain filling, and their relationships with the filling rate, gel consistency (GC), alkali spreading value (ASV) and amylose content (AC) were studied. The results showed that changes in activities of ADPGPase, SSase and Q-enzyme exhibited a single peak during grain filling, and the time of the activity peaks for the former two enzymes was earlier than that of the maximum grain-filling rate (Tmax), and the time reaching the peak for Q-enzyme was synchronous with Tmax. The activities at early grain filling stage, and the mean and maximum activities of each enzyme during grain filling period were positively and significantly or very significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in the grains.Activities of ADPGPase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were not significantly correlated the cooking quality (GC, ASV and AC). SSase activities at the early filling stage were significantly and negatively correlated with GC and ASV, and positively correlated with AC. Activities of SSase at mid and late grain filling stages and Q-enzyme at the late filling stage were significantly and positively correlated with GC and ASV, and negatively correlated with AC. Spraying zeatin or abscisic acid at early grain filling stage could obviously regulate the activities of ADPGPase, SSase and Q-enzyme in the grains.     

灌浆期温度和水分对玉米籽粒建成及粒重的影响

综述了玉米的籽粒建成，灌浆期温度和干旱胁迫对于玉米籽粒建成和粒重的影响，指出温度胁迫减少了胚乳细胞数目、淀粉粒数量、降低籽粒的灌浆速率，缩短了灌浆持续时间；干旱胁迫使灌浆期同化物供应不足，胚乳细胞分裂受抑制，籽粒有效灌浆期缩短；二者造成粒重降低。同时对此方面的研究提出了看法。     

灌浆期遮光对糯小麦和非糯小麦淀粉组分及理化特性的影响

【目的】揭示灌浆期遮光对糯小麦和非糯小麦籽粒淀粉理化特性影响的差异,探讨籽粒淀粉组分与理化特性的内在联系。【方法】大田条件下,选用非糯小麦品种轮选987和糯小麦品种农大糯50222,分别于灌浆前期(花后1—10 d)、灌浆中期(花后11—20 d)和灌浆后期(花后21—30 d)遮去60%的光合有效辐射处理,以大田自然光强为对照(CK),研究灌浆期遮光对糯小麦和非糯小麦籽粒淀粉组分和理化特性的影响。【结果】灌浆期遮光显著降低小麦籽粒总淀粉、直链淀粉和支链淀粉含量,其中灌浆前期遮光降低幅度最大,而灌浆后期最小,且弱光对轮选987总淀粉含量的影响大于农大糯50222。灌浆期遮光轮选987直/支比值增大;而农大糯50222的直/支比值在灌浆前期和中期遮光后减小,灌浆后期遮光无变化;灌浆前期和后期遮光显著提高轮选987淀粉B型淀粉粒的体积、表面积和数目比例,降低A型淀粉粒的体积、表面积和数目比例,而灌浆中期遮光则呈相反趋势。灌浆期遮光均显著提高了农大糯50222淀粉B型淀粉粒的体积、表面积和数目比例,降低了A型淀粉粒的体积、表面积和数目比例。灌浆期遮光两小麦淀粉的相对结晶度呈降低趋势,遮光对其影响程度随遮光时期的延迟而减小,且农大糯50222淀粉的相对结晶度显著大于轮选987。灌浆前期和灌浆中期遮光降低了轮选987淀粉的峰值黏度、谷值黏度、最终黏度和稀懈值。灌浆各时期遮光均降低了农大糯50222淀粉的上述指标,但仍高于轮选987。相关性分析表明,直链淀粉含量、直支比值与最终黏度、反弹值、峰值黏度、谷值黏度及糊化时间呈显著负相关,支链淀粉含量与其呈显著正相关。B型淀粉粒的体积比例与最终黏度和反弹值呈显著负相关。B型淀粉粒表面积比例和相对结晶度、最终黏度、反弹值、糊化时间呈显著正相关,与糊化温度呈显著负相关。【结论】灌浆期遮光改变了小麦胚乳淀粉组分、粒度分布、相对结晶度及其主要糊化特征参数。小麦胚乳淀粉组分与晶体特性和糊化特性之间均存在明显的相关性,表明遮光影响了小麦淀粉组分,间接影响了其理化特性。     

Wx蛋白组成对小麦籽粒淀粉合成的影响

 【目的】通过对籽粒淀粉积累和淀粉合成关键酶的活性进行比较,初步明确不同Wx蛋白组成小麦品种淀粉理化特性差异的酶学基础。【方法】以6类Wx蛋白组成的14个小麦品种为试材,测定其籽粒灌浆过程中直、支链淀粉积累动态和4种淀粉合成关键酶的活性变化,对测定结果进行统计分析。【结果】Wx蛋白数目和类型对4种淀粉合成关键酶活性和直、支链淀粉合成有明显影响。随着Wx蛋白数目的增多,4种淀粉合成关键酶活性呈现升高的趋势,尤其是淀粉粒束缚淀粉合成酶（GBSS）,籽粒直链淀粉含量也相应升高。Wx-B1缺失蛋白对GBSS活性影响最大,直链淀粉合成能力下降最明显,其次是缺失Wx-D1蛋白,Wx-A1蛋白缺失作用最小。籽粒灌浆过程中,4种淀粉合成关键酶活性高度相关,并与直、支链淀粉含量密切相关,说明直、支链淀粉的合成是相互影响、相互制约、同步进行的。【结论】Wx基因是影响籽粒直链淀粉含量的重要决定因素,Wx基因可以通过自身数目和组成的变化,控制GBSS的活性,并对其它淀粉合成关键酶的活性产生影响,最终影响直、支链淀粉的合成,形成不同的淀粉理化特性和加工品质。     

玉米籽粒灌浆速率研究进展

玉米的产量很大程度上受灌浆阶段干物质积累量的影响,灌浆期长短和灌浆速率决定了粒重和产量水平,而灌浆速率受相关基因或QTL以及栽培条件共同调控,表现出复杂的动态变化特征。从灌浆速率的生理代谢、关键酶活性以及遗传与环境等方面概述了玉米籽粒灌浆速率的研究进展。探究玉米籽粒灌浆的分子调控机制将为玉米高产育种提供必要的理论依据。     

Effects of Shading at Different Stages After Anthesis on Maize Grain Weight and Quality at Cytology Level

The objective of the current study is to investigate the effects of different stages of shading after anthesis on grain weight and quality of maize at cytology level.The shading experiments were conducted in the field from 2005 to 2006,with a common maize cultivar(TY2)as the experimental material.Plants were given stress using horizontal shading net and the light intensity was reduced by 55%.Field-grown maize plants were shaded at 1-14 d(S1),15-28 d(S2),and 29-42 d(S3)after pollination,respectively.Control plants(S0)were grown under natural light.Grain weight,quality,endosperm cell proliferation,cob sugar content,and grain pedicel vascular bundle cross section area were measured.The ultrastructural changes of endosperm cells and endosperm transfer cells were observed after pollination.The result indicated that the grain weight,starch content,endosperm cell number,and volume were declined after shading.On the contrary,the proportion of embryo and endosperm,protein content,and fat content in grain increased.Shading treatments significantly delayed the development of the starch granules and remarkably reduced the endosperm filling status.Among the three treatments.the number of the grain endosperm was the least under shading stress at 1-14 d after pollination.However,the volume of starch granules and the substantiation of endosperm under shading treatment at 15-28 d after pollination were the worst.Compared with the control(natural sunlight without shading),the soluble sugar of maize cob increased significantly,while there was no obvious change in vascular structure of small cluster stalk.The number of protein body in maize endosperm was influenced markedly by low light at different stages after pollination.Low light decreased the volume of the grain endosperm transfer and the cell wall extensions of the basal transfer cells became thinner and shorter under shading treatment than those of the control.Furthermore,the degree of connection and the capacity of the nutrient transport were decreased and the mitochondrion number of the transfer cell was reduced after shading.The change in grain quality after shading was observed due to increase in the proportion of embryo and endosperm.The morphology and functions in endosperm transfer cell and the shortage of energy restricted the nutrient transport greatly with shading at different stages,suggesting that an impeded flux may be one of the important reasons for the reduction of maize grain weight of maize grain at later growth stage under low light condition.     

米粉专用稻稻米直链淀粉含量的化学调控

为提高米粉专用稻稻米品质,采用齐穗期喷施的方法,研究了2种化学调节剂(自配)对米粉专用稻湘早籼33号稻米直链淀粉含量的影响及其生理基础.结果表明,化学调节剂通过影响米粉稻剑叶同化产物的分配及其籽粒中蔗糖和淀粉的积累,调节稻米直链淀粉含量;一种调节剂能降低直链淀粉含量;另一种调节剂能提高直链淀粉含量.     

不同施氮时期对淀粉积累及淀粉合成相关酶类活性变化的研究

选用2个不同直链淀粉含量的杂交水稻组合,采用不同施氮期处理,对水稻开花后籽粒灌浆、淀粉积累、淀粉合成关键酶类活性及其之间的关系进行研究.结果表明,侧重后期施氮可以促进籽粒灌浆、增加粒重,同时还可适当提高稻米支链淀粉含量.不同施氮期处理条件下,与淀粉合成相关的3个关键酶的活性峰值出现的时间基本上未明显变化,但是酶活性大小及峰值高低有所不同,其中淀粉合成酶和ADPG焦磷酸化酶活性差异较大,而分支酶活性变化较小.侧重前期施氮有利于提高淀粉合成酶活性,而侧重后期施氮则可提高ADPG焦磷酸化酶和淀粉分枝酶活性.籽粒灌浆期淀粉合成酶平均活性及灌浆中、后期的ADPG焦磷酸化酶和淀粉分枝酶活性与籽粒灌浆速率及直链淀粉、支链淀粉积累速率呈显著或极显著正相关.ADPG焦磷酸化酶和淀粉分枝酶活性对直、支链淀粉含量变化均有同等重要的作用.侧重后期施氮处理有利于提高直、支链淀粉积累速率.     

不同淀粉含量玉米品种籽粒淀粉积累特性比较

本研究以两个高淀粉玉米品种和两个普通玉米品种为试验材料,研究了高淀粉玉米与普通玉米在籽粒灌浆过程中淀粉动态积累的差异。结果表明：灌浆过程中4个品种淀粉含量变化趋势均呈＂S＂型曲线变化;高淀粉玉米和普通玉米在灌浆初期籽粒直链淀粉含量并无显著差异,而在灌浆中后期才逐渐表现差异;与直链淀粉积累不同,两个高淀粉品种籽粒支链淀粉含量在灌浆初期就明显高于两个普通玉米品种,籽粒灌浆前期平均灌浆速率与最大灌浆速率高有利于籽粒支链淀粉的积累;籽粒总淀粉积累的差异主要是由于支链淀粉积累的不同造成的,直链淀粉积累差异不明显。     

不同施氮时期对水稻淀粉积累及淀粉合成 相关酶类活性变化的研究

 选用2个不同直链淀粉含量的杂交水稻组合，采用不同施氮期处理，对水稻开花后籽粒灌浆、淀粉积累、淀粉合成关键酶类活性及其之间的关系进行研究。结果表明，侧重后期施氮可以促进籽粒灌浆、增加粒重，同时还可适当提高稻米支链淀粉含量。不同施氮期处理条件下，与淀粉合成相关的3个关键酶的活性峰值出现的时间基本上未明显变化，但是酶活性大小及峰值高低有所不同，其中淀粉合成酶和ADPG焦磷酸化酶活性差异较大，而分支酶活性变化较小。侧重前期施氮有利于提高淀粉合成酶活性，而侧重后期施氮则可提高ADPG焦磷酸化酶和淀粉分枝酶活性。籽粒灌浆期淀粉合成酶平均活性及灌浆中、后期的ADPG焦磷酸化酶和淀粉分枝酶活性与籽粒灌浆速率及直链淀粉、支链淀粉积累速率呈显著或极显著正相关。ADPG焦磷酸化酶和淀粉分枝酶活性对直、支链淀粉含量变化均有同等重要的作用。侧重后期施氮处理有利于提高直、支链淀粉积累速率。     

云南软米直链淀粉含量遗传分析

应用胚乳性状遗传模型,采用单粒法对云南软米品种毫屁和非软米品种桂朝2号直链淀粉含量(AC)的遗传规律进行研究.结果表明,毫屁和桂朝2号杂交,F_2代表现出高直链淀粉含量对低直链淀粉含量呈3∶ 1分离,与软米特性有关的低直链淀粉含量基因受1对隐性主效基因控制.除主效基因控制外,还有部份修饰基因作用.     

Development of elite restoring lines by integrating blast resistance and low amylose content using MAS

Blast resistance and grain quality are major problems in hybrid rice production in China. In this study, two resistance (R) genes, Pi46 and Pita, along with the gene Wx^b, which mainly affects rice endosperm amylose content (AC), were introgressed into an elite indica restoring line, R8166, which has little blast resistance and poor grain quality through marker-assisted selection (MAS). Eight improved lines were found to have recurrent genome recovery ratios ranging from 88.68 to 96.23%. Two improved lines, R163 and R167, were selected for subsequent studies. R167, which has the highest recovery ratio (96.23%), showed no significant differences in multiple agronomic traits. In contrast, R163 with the lowest recovery ratio (88.68%) exhibited significant differences in heading date and yield per plant compared with the recurrent parent. At two developmental stages, R163 and R167 had greatly enhanced resistance to blast over the recurrent parent. Similar trends were also observed for agronomic traits and blast resistance in R163- and R167-derived hybrids when compared with the counterparts from R8166. In addition, R163, R167, and their derived hybrids significantly improved the grain quality traits, including amylose content (AC), gel consistency (GC), chalky grain rate (CGR), and degree of endosperm chalkiness (DEC). It confirmed the success of efficiently developing elite restoring lines using MAS in this study.     

Effect of Soil Texture on Starch Accumulation and Activities of Key Enzymes of Starch Synthesis in the Kernel of ZM 9023

Three kinds of soil texture （clay-loam, mid-loam, and sand-loam soil） were used to study the effects of soil texture on starch accumulating rate and the changes in activities of the key enzymes of starch synthesis in the kernel during grain filling in high gluten content wheat ZM 9023, under conditions of pond culture. The content of starch and its components were measured according to the method of double-wave length described by Bao （1996）. ADP-glucose pyrophosphorylase （AGPP） activity was tested according to the method described by Doehlert et al. （1988）. Soluble starch synthase （SSS） and starch branching enzyme （SBE） activities were tested according to the method described by Nakamura et al. （1989）. The amylose, amylopectin, and total starch accumulating rate in the kernel of ZM 9023 were found to be a single-peak curve in three different soil textures during grain filling, and peaked 20, 15, and 15 d after anthesis, respectively. The activities of the enzymes, AGPP, SSS, and SBE, in the kernel of ZM 9023 had a single-peaked curve, which peaked 20, 15, and 15 d after anthesis, respectively. The activities of the above three enzymes of ZM 9023 were higher in the sand-loam soil. The accumulating peak of amylose formed later compared to that of amylopectin. The sand-loam soil could help high gluten content cultivars to synthesize starch.     

水稻GBSS与淀粉分支酶基因转录本丰度对直链淀粉含量的影响

为探讨水稻胚乳淀粉合成相关酶基因表达丰度与直链淀粉含量(AC)的相关性,为稻米品质改良提供指导,以127份早籼稻,143份晚粳稻和19份粳糯稻为材料,应用水稻胚乳RNA阵列分析了供试品系的直链淀粉含量和Wx(包括成熟转录本和非成熟转录本)、Sbe I基因mRNA丰度之间的相关性。结果表明,Wx基因非成熟转录本的剪接及修饰对AC值的大小起着十分重要的决定作用。而sbeI基因在不同品系间的相对表达丰度与相对应的AC值无直接相关性。     

夏玉米籽粒发育过程中淀粉积累与粒重的关系

利用显微解剖和组织化学的方法,系统观察了夏玉米籽粒(颖果)发育过程中淀粉的分布与消长,结果表明:在成熟胚囊至原胚期,子房柄、子房壁、卵细胞、助细胞、中央细胞、合子、原胚及游离核胚乳中存在许多小球形淀粉粒,处于不断积累同时又不断被利用的状态,是碳水化合物的暂时性贮藏形式,对籽粒的器官建成起重要的营养作用。胚器官分化期,胚和胚乳中开始形成淀粉粒,随籽粒发育,其数量和体积逐渐增加,直到籽粒完全成熟。这些淀粉粒是碳水化合物的永久性贮藏形式,积累的先后顺序及充分程度与籽粒重量、品质密切相关。     

水稻直链淀粉含量选择对淀粉合成关键酶活性影响

选用直链淀粉含量有显著差异的杂交后代及亲本,分析其灌浆过程中籽粒淀粉积累和合成关键酶活性变化。结果表明,通过籽粒直链淀粉含量的选择不仅可以提高或降低杂种后代的直链淀粉合成和积累速度,而且还可以明显改变籽粒淀粉合成关键酶活性大小;直链淀粉含量低的后代ADPG焦磷酸化酶和可溶性淀粉合成酶活性达到峰值的时间比含量较高的后代要早,而淀粉分支酶活性达到峰值时间与此相反。     

不同糯性高粱胚乳淀粉形成与积累过程的酶学调控机制及显微结构变化

【目的】高粱是酿造白酒和食醋的主要原料,其淀粉组成和结构是影响高粱酿造品质的主要指标。通过研究淀粉积累过程中相关酶活性和淀粉粒超微结构的变化动态,解析高粱淀粉合成与积累的酶学调控机制,了解不同糯性高粱胚乳淀粉的超微结构特点,以期为酿造高粱的优质育种和栽培技术研究提供理论依据。【方法】以辽粘3号、辽杂19和辽杂10号3种不同糯性的高粱品种籽粒为研究对象,利用酶学及扫描电镜技术检测淀粉积累过程中相关酶活性的变化,观测淀粉积累过程中淀粉粒的形成过程及结构特征,利用相关分析研究淀粉合成过程中相关合成酶类的调控作用。【结果】淀粉合成过程中,不同胚乳类型高粱的尿苷二磷酸葡萄糖焦磷酸化酶（UDPG）、腺苷二磷酸葡萄糖焦磷酸化酶（ADPG）、可溶性淀粉合成酶（SSS）、结合态淀粉合成酶（GBSS）、淀粉分支酶（SBE）、淀粉去分支酶（DBE）活性均呈单峰曲线变化趋势;糯高粱结合态淀粉合成酶（GBSS）活性呈单峰曲线变化趋势,粳高粱、半粳半糯高粱则表现双峰曲线变化趋势。UDPG、ADPG、SSS活性与直链淀粉、支链淀粉积累速率显著正相关,SBE、DBE活性与支链淀粉积累速率呈显著正相关,GBSS活性与粳高粱、半粳半糯高粱直链淀粉积累速率呈显著正相关,与糯高粱直链淀粉积累速率表现正相关的趋势,但相关不显著。不同胚乳类型高粱淀粉粒的充实过程表现相似变化趋势,在开花后的14—35 d充实较快。糯高粱的淀粉粒较小,直径在10 μm以内,内部有圆孔型或楔形空洞。粳高粱淀粉粒较大,呈不规则球形,内部空洞极少。半粳半糯型高粱淀粉粒粒径分布较广,多数分布楔形或星形空洞,少部分无空洞。【结论】UDPG、ADPG、SSS是调控淀粉合成的关键酶,GBSS、SBE、DBE是调控淀粉组分比例的关键酶,SBE、DBE活性高是糯高粱支链淀粉含量高的主要原因,不同淀粉组分比例可能是影响淀粉粒结构的主要因素。