不同供水条件对小麦强、弱势籽粒中淀粉粒度分布的影响

以3个淀粉含量不同的冬小麦品种山农12、鲁麦21和济南17为材料,设灌溉和旱作2种栽培处理,对不同水分条件下小麦强、弱势籽粒中淀粉粒的体积、数目和表面积的分布特征进行了研究.结果表明,小麦强、弱势籽粒均含有A(＞9.8 μm)、B(2.0～9.8 μm)、C(＜2.0 μm)3种类型的淀粉粒,但不同类型淀粉粒的分布状况存在明显差异.在强势籽粒中,淀粉粒的体积和表面积分布均表现为三峰分布,而弱势籽粒中淀粉粒的体积和表面积分布则表现为双峰分布.与弱势粒相比较,强势粒中C型淀粉粒(＜2.0 μm)的体积百分比为7.25%～9.31%,表面积百分比为34.88%～41.51%,而弱势粒的体积和表面积百分比分别为5.33%～6.40%和26.31%～33.54%.强、弱势籽粒中＜0.6 μm和0.6～2.0 μm范围内的淀粉粒数目存在明显差异,强势粒为1.86%～6.13%和83.77%～87.77%,而弱势粒为25.72%～37.42%和52.77%～58.48%.与灌溉栽培相比较,旱作栽培条件下籽粒中B、C型淀粉粒体积和表面积百分比显著增加,而A型淀粉粒体积和表面积显著减少;弱势粒中＜0.6 μm的淀粉粒数目显著增加,强势籽粒中淀粉粒的数目无显著变化.与弱势粒相比较,强势粒中的蛋白质含量较高,C型淀粉粒的体积和表面积所占比例较大,而强势粒中的淀粉含量较低,且A、B型淀粉粒比例也较小.与灌溉栽培相比较,旱作栽培条件下强、弱势籽粒中B、C型淀粉粒体积和表面积百分比增加,蛋白质含量也显著增加,淀粉含量降低.表明水分亏缺能提高籽粒中B、C型淀粉粒体积和表面积百分比及蛋白质含量.     

灌溉与旱作条件下源库关系对小麦籽粒淀粉粒度分布的调节效应

在灌溉和旱作两种栽培条件下,研究了源库关系对小麦籽粒淀粉粒度分布特征的影响.结果表明,山农8355(大穗型)各处理A型淀粉粒体积分布、表面积分布百分比成熟期较灌浆中期明显提高,灌溉栽培条件下增幅分别在17.65%～22.88%、35.8%～39.05%,旱作栽培条件下增幅分别在1.46%～2.82%、7.05%～8.12%;山农8355各处理B型淀粉粒体积分布、表面积分布百分比成熟期较灌浆中期明显降低,灌溉栽培条件下降幅分别在34.78%～40.47%、11.73%～13.77%,旱作栽培条件下降幅分别在5.08%～7.67%、2.52%～3.43%.济南17(多穗型)各处理下成熟期与灌浆中期的A、B淀粉粒体积分布、表面积分布百分比,其变化趋势与山农8355相同,其中A型淀粉粒灌溉栽培条件下增幅分别在1.56%～5.98%、2.96%～9.92%,旱作栽培条件下增幅分别在1.76%～4.52%、1.28%～8.63%;B型淀粉粒灌溉栽培条件下降幅分别在3.46%～12.27%、1 02%～4.18%,旱作栽培条件下增幅分别在5.31%～9.87%、0.58%～3.13%.在灌溉和旱作栽培条件下源库调节对两品种A、B型淀粉粒粒度分布的影响趋势表现为,减源处理A型淀粉粒较同期同品种对照处理的体积分布、表面积分布百分比显著提高,减库处理较同期同品种对照处理显著降低,B型淀粉粒粒度分布变化趋势则与之相反.     

小麦籽粒发育及淀粉晶体特性对花后高温胁迫的响应

选用2个品质类型和成熟期不同的新疆主栽小麦品种‘新春11号’和‘新春39号’,分别进行花后灌浆早期高温(花后5~8d,32℃,T_1)和中期高温(花后15~18d,38℃,T_2)处理,分析花后高温对小麦籽粒发育及淀粉晶体的影响。结果显示:(1)T_1处理明显降低了两品种籽粒长度和粒重,而T_2处理显著影响籽粒宽度和厚度;高温处理虽然降低了籽粒灌浆速率,但两品种灌浆最大峰值出现时间均在花后18d。(2)T_1处理对小麦籽粒A型淀粉粒形态的影响较大,中熟品种‘新春11号’的A型淀粉粒表面在花后10d时可观察到微孔,在花后15~20d时其粒径明显小于同期对照,在花后20~25d时淀粉粒表面压痕增多且A、B型淀粉粒表面出现明显缢缩;而早熟品种‘新春39号’淀粉粒形态和粒径大小受花后高温的影响相对较小。(3)两品种在不同高温处理下,其淀粉粒晶体特性衍射峰出现的位置相同,但淀粉粒的尖峰强度不同,表明高温胁迫不影响淀粉粒的晶体类型,但可能改变了淀粉粒内部的层状结构。研究表明,花后早期高温不仅对小麦籽粒外部形态有较大的影响,同时也影响到籽粒内部淀粉粒的形态和晶体的特性。     

强筋与弱筋小麦籽粒蛋白质组分与加工品质对灌浆期弱光的响应

选用强筋小麦品种济麦20和弱筋小麦品种山农1391,在大田试验条件下,分别于籽粒灌浆前期(花后6—9 d)、中期(花后16—19 d)和后期(花后26—29 d)对小麦进行弱光照处理,研究了籽粒产量、蛋白质组分及加工品质的变化。灌浆期弱光显著降低小麦籽粒产量,灌浆中期对济麦20和灌浆后期对山农1391的产量降幅最大。弱光处理后,籽粒氮素积累量及氮素收获指数减少。但弱光使籽粒蛋白质含量显著升高,其中灌浆中期弱光升幅最大,原因可能是由于其粒重降低造成的。弱光对可溶性谷蛋白无显著影响,但增加不溶性谷蛋白含量,使谷蛋白聚合指数显著升高,面团形成时间和稳定时间亦升高,籽粒灌浆中、后期弱光对上述指标的影响较前期大。灌浆期短暂的弱光照对改善强筋小麦粉质仪参数有利,但使弱筋小麦变劣;并均伴随籽粒产量的显著降低这一不利影响。     

花后高温对不同耐热性小麦品种籽粒淀粉形成的影响

以耐热性不同的2个小麦品种济麦20和鲁麦21为材料,分别于花后5～9d（T1）和15～19d（T2）进行高温处理,研究了小麦花后不同阶段高温对籽粒淀粉积累、淀粉粒分布及相关酶活性的影响。结果表明,花后高温显著降低籽粒淀粉积累量;显著降低籽粒淀粉及支链淀粉含量,但提高直链淀粉含量、直／支链淀粉比例。处理间比较,他处理对籽粒淀粉积累的影响程度较T1处理大。品种间比较,高温对济麦20的影响程度较鲁麦21大。高温使A型淀粉粒的体积、数量和表面积比例显著增加,B型淀粉粒的体积、数量和表面积比例显著降低。T1处理后,两品种籽粒蔗糖含量、蔗糖合酶（SS）和腺苷二磷酸葡萄糖焦磷酸化酶（AGPP）、可溶性淀粉合酶（SSS）、束缚态淀粉合酶（GBSS）和淀粉分支酶（SBE）活性均略高于对照;但济麦20、鲁麦21上述指标分别于花后15、20d开始低于对照。他处理后,两品种籽粒蔗糖含量、SS、AGPP、SSS、GBSS和SBE活性显著低于对照,济麦20上述指标的降幅较鲁麦21大。与其它淀粉合成相关酶相比,高温对籽粒GBSS活性的影响程度较小。两品种处理间籽粒蔗糖含量、SS、AGPP、SSS、GBSS及SBE活性的变化趋势,与淀粉积累量的变化趋势基本一致。说明灌浆期高温使籽粒淀粉积累量降低,一方面是由于籽粒蔗糖供应较低引起糖源不足;另一方面则是由于灌浆中后期淀粉合成相关酶活性下降使淀粉合成受抑所致。     

施氮水平对小麦籽粒谷蛋白大聚合体粒径分布的调控效应

谷蛋白大聚合体(GMP)是决定小麦品质形成的重要因素,在小麦籽粒发育过程中,GMP以球形颗粒形式贮藏在小麦籽粒胚乳中,其含量及颗粒大小受亚基组成及环境条件的影响。本研究以不同穗型冬小麦品种为材料,通过大田试验探讨了施氮水平与小麦籽粒谷蛋白大聚合体含量及其颗粒粒径分布的关系。结果表明,在0—240kg?hm-2范围内增施氮肥能显著提高小麦籽粒中GMP的含量,施氮量继续增加则不利于小麦籽粒 GMP积累。小麦籽粒GMP颗粒粒径分布范围为0.375—256 μm;GMP颗粒的体积和表面积分布均呈双峰曲线,数目分布呈单峰曲线。在0—240kg?hm-2范围内增施氮肥能显著提高>10μmGMP颗粒数目百分比和体积百分比,表明施氮能促进大颗粒GMP的形成。不同品种对施用氮肥的反应呈现差异。大穗型品种泰山9818籽粒GMP含量及颗粒粒径分布对氮肥的反应较为敏感。     

不同灌水处理对强筋小麦谷蛋白大聚合体粒度分布和品质的影响

在田间条件下,以两个优质强筋小麦品种(藁城8901和济麦20)为供试材料,研究了不同灌水处理(全生育期不灌水、拔节期灌1次水、越冬期和拔节期灌2次水、越冬期、拔节期和灌浆期灌3次水,每次灌水量675 m³·hm^-2)对强筋小麦谷蛋白大聚合体含量与粒度分布、品质和产量的影响.结果表明: 两个小麦品种的面团形成时间、面团稳定时间、面包体积、籽粒产量、谷蛋白大聚合体含量以及体积加权平均粒径、表面积加权平均粒径、粒径>100 μm的体积百分比和表面积百分比均以灌2水处理最高.相关分析显示,两个小麦品种的面团形成时间、面团稳定时间和面包体积与粒径<10 μm和10～100 μm的谷蛋白大聚合体颗粒体积百分比呈显著负相关,而与粒径>100 μm的谷蛋白大聚合体颗粒体积百分比、体积加权平均粒径和表面积加权平均粒径呈显著正相关.水分供应过多或过少均不利于籽粒产量和品质的同步改善,灌溉水平可通过改变谷蛋白大聚合体粒度分布影响小麦籽粒品质.     

花后不同时期弱光和高温胁迫对小麦旗叶荧光特性及籽粒灌浆进程的影响

在田间试验条件下研究了花后不同时期弱光和高温胁迫对小麦旗叶荧光特性及籽粒灌浆进程的影响.结果表明,弱光处理3 d后,旗叶PSⅡ最大光化学效率（Fv/Fm）和光合速率（Pn）显著降低,但PSⅡ实际光化学效率（ΦPSⅡ）、荧光光化学猝灭系数（qP）和非光化学猝灭（NPQ）与对照相比差异较小;高温处理3 d后,Fv/Fm、Pn、ΦPSⅡ和qP均极显著降低, NPQ升高幅度较小.胁迫解除后,灌浆前期（花后8～10 d）弱光和高温处理后的旗叶荧光参数和光合速率略有恢复,但灌浆中期（花后15～17 d）处理后的各参数始终呈下降趋势, 说明前期处理效应是可逆的,而中期处理加速其衰老进程.用Logistic方程对各处理的籽粒灌浆过程模拟明,弱光和高温处理后籽粒粒重的降低主要是平均灌浆速率、最大灌浆速率和渐增期灌浆速率显著降低所致.灌浆持续期、最大灌浆速率出现时间、缓增持续期和缓增期灌浆速率受弱光和高温影响较小.     

氮肥后移对花后受渍冬小麦灌浆特性及产量构成的影响

2010～2012年连续2个生长季,以小麦品种‘烟农19’为材料,大田试验按基肥∶拔节肥∶孕穗肥比例设为氮肥处理N1(10∶0∶0)、N2(7∶3∶0)、N3(5∶5∶0)、N4(3∶5∶2),采用多项式、Logistic方程拟合不同氮肥运筹对花后受渍冬小麦灌浆期籽粒体积与干重变化过程,研究不同氮肥运筹对花后受渍冬小麦灌浆特性及产量构成的影响.结果表明:(1)两年度间各指标变化趋势基本一致,故各指标结果按其两年度平均值计算.(2)花后渍水使冬小麦籽粒体积减小11.8％,灌浆速率降低15.4％,灌浆历期缩短9.2％,千粒重降低20.9％,穗粒数减少7.0％,籽粒产量降低26.6％,而对穗数无显著影响.相对于氮肥全部作为基肥处理N1,氮肥后移处理N2、N3、N1的小麦籽粒体积分别增加10.2％、15.0％、19.4％,灌浆速率分别提高8.5％、16.0％、18.2％,灌浆历期分别延长5.0％、9.4％、11.5％,千粒重分别增加11.9％、20.2％ 、25.6％,穗粒数分别增加7.9％、12.3％、14.6％,产量分别提高18.1％ 、29.6％、37.6％,而穗数分别降低2.2％、3.8％、4.3％.(3)各灌浆参数与冬小麦籽粒产量的关联度表明,花后渍水逆境对灌浆速率的影响大于对灌浆历期的影响,氮肥后移主要通过提高小麦中后期灌浆速率缓解渍水逆境胁迫伤害.研究认为,在花后土壤受渍冬小麦生产区,生产中可获得最高小麦产量的最佳氮肥运筹模式为N4(3∶5∶2)处理.     

两种穗型冬小麦籽粒淀粉积累动态及其有关酶活性变化

花后25d内,大穗型品种豫麦66籽粒中淀粉积累比多穗型品种豫麦49慢,但花后25d后情况则相反。2个品种籽粒中淀粉积累速率的变化均呈单峰曲线,豫麦49峰值出现在花后15～20d,而豫麦66峰值则出现在花后20～25d。灌浆期豫麦66和豫麦49籽粒中蔗糖合成酶(SS)活性变化呈单峰曲线,峰值分别出现在花后20d和15d,整个灌浆期内豫麦66籽粒中SS活性高于豫麦49;2个品种籽粒中腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)和淀粉分支酶(SBE)活性变化均呈单峰曲线,峰值出现在花后20d,而可溶性淀粉合成酶(SSS)活性变化则呈双峰曲线,峰值分别出现在花后10d和20d,且第二个峰值显著高于第一个。相关分析表明,SS、AGPP、SSS和SBE是影响小麦籽粒淀粉积累的关键酶。     

Starch granule initiation in Arabidopsis thaliana chloroplasts

The initiation of starch granule formation and the mechanism controlling the number of granules per plastid have been some of the most elusive aspects of starch metabolism. This review covers the advances made in the study of these processes. The analyses presented herein depict a scenario in which starch synthase isoform 4 (SS4) provides the elongating activity necessary for the initiation of starch granule formation. However, this protein does not act alone; other polypeptides are required for the initiation of an appropriate number of starch granules per chloroplast. The functions of this group of polypeptides include providing suitable substrates (maltooligosaccharides) to SS4, the localization of the starch initiation machinery to the thylakoid membranes, and facilitating the correct folding of SS4. The number of starch granules per chloroplast is tightly regulated and depends on the developmental stage of the leaves and their metabolic status. Plastidial phosphorylase (PHS1) and other enzymes play an essential role in this process since they are necessary for the synthesis of the substrates used by the initiation machinery. The mechanism of starch granule formation initiation in Arabidopsis seems to be generalizable to other plants and also to the synthesis of long-term storage starch. The latter, however, shows specific features due to the presence of more isoforms, the absence of constantly recurring starch synthesis and degradation, and the metabolic characteristics of the storage sink organs.     

The phenotype of soluble starch synthase IV defective mutants of Arabidopsis thaliana suggests a novel function of elongation enzymes in the control of starch granule formation

All plants and green algae synthesize starch through the action of the same five classes of elongation enzymes: the starch synthases. Arabidopsis mutants defective for the synthesis of the soluble starch synthase IV (SSIV) type of elongation enzyme have now been characterized. The mutant plants displayed a severe growth defect but nonetheless accumulated near to normal levels of polysaccharide storage. Detailed structural analysis has failed to yield any change in starch granule structure. However, the number of granules per plastid has dramatically decreased leading to a large increase in their size. These results, which distinguish the SSIV mutants from all other mutants reported to date, suggest a specific function of this enzyme class in the control of granule numbers. We speculate therefore that SSIV could be selectively involved in the priming of starch granule formation.     

禾谷类作物淀粉合酶

淀粉合酶是禾谷类作物淀粉合成所必需的一类酶.根据淀粉合酶家族成员的氨基酸序列的相似性,分别介绍了一个颗粒性淀粉合酶亚家族和四个可溶淀粉合酶亚家族的组成、基因结构和表达特点,并从转录、转录后和翻译后水平上对这些基因的表达调控做了概述.     

魔芋球茎贮藏淀粉和甘露聚糖粒的形态观察

在光学显微镜和透射电镜下观察了魔芋（Ａｍｏｒｐｈｏｐｈａｌｕｓｃｏｎｊａｃ）球茎中甘露聚糖粒和淀粉粒的形态。两种贮藏多糖分别位于不同的细胞中。淀粉粒在造粉体内发育,以复粒存在,用魔芋球茎仔茎茎尖为材料观察显示,淀粉粒的形成早于甘露聚糖颗粒的形成。甘露聚糖粒形态多数近随圆形,一些甘露聚糖颗粒内包含了针晶体,但多数的甘露聚糖粒内部不包含针晶体,由纯净的甘露聚糖构成。     

NOTE—THE STA-1 MUTATION PREVENTS ASSEMBLY OF STARCH GRANULES IN NITROGEN-STARVED CELLS AND SERVES AS A USEFUL MORPHOLOGICAL MARKER DURING SEXUAL REPRODUCTION IN CHLAMYDOMONAS MONOICA (CHLOROPHYCEAE)

Iodine staining of clones of nitrogen-starved Chlamydomonas cells was used to screen for mutants with altered levels or altered composition of storage starch. Mutations leading to defects in quantity or morphology of starch granules not only can provide information on storage starch biosynthesis and granule assembly but can also be used as morphological markers in genetic and cell biological studies. A mutant of Chlamydomonas monoica Strehlow devoid of starch granules was obtained following ultraviolet mutagenesis. Nitrogen-starved cells of the sta-1 strain lacked pyrenoidal starch granules and granules normally associated with thylakoid membranes. The mutant phenotype was the consequence of a single Mendelian mutation that appeared to affect granule assembly rather than starch biosynthesis per se and that had no effect on vegetative growth, sexual reproduction, or zygospore viability.     

马铃薯表观淀粉含量与直链淀粉含量相关性研究

测定了48个不同马铃薯品种表观淀粉含量以及块茎中和淀粉中直链淀粉含量,对表观淀粉含量和块茎中直链淀粉含量间,表观淀粉含量和淀粉粒直链淀粉含量间进行了相关分析。结果表明：表观淀粉含量和块茎中直链淀粉含量间相关显著,表观淀粉含量和淀粉粒直链淀粉含量间相关不显著,且中熟和晚熟基因型表观淀粉含量和淀粉粒直链淀粉含量间相关也不显著,这些结论将为淀粉生物合成的理论研究和淀粉品质改良提供基本的表型数据。     

Effects of protein on crosslinking of normal maize, waxy maize, and potato starches

Channels of maize starch granules are lined with proteins and phospholipids. Therefore, when they are treated with reagents that react at or near the surfaces of channels, three types of crosslinks could be produced: protein–protein, protein–starch, starch–starch. To determine which of these may be occurring and the effect(s) of channel proteins (and their removal) on crosslinking, normal and waxy maize starches were treated with a proteinase (thermolysin, which is known to remove protein from channels) before and after crosslinking, and the properties of the products were compared to those of a control (crosslinking without proteinase treatment). After establishing that treatment of starch with thermolysin alone had no effect on the RVA trace, three reaction sequences were used: crosslinking alone (CL), proteinase treatment before crosslinking (Enz-CL), proteinase treatment after crosslinking (CL-Enz). Two crosslinking reagents were used: phosphoryl chloride (POCl₃), which is known to react at or near channel surfaces; STMP, which is believed to react throughout the granule matrix. Three concentrations of POCl₃ (based on the weight of starch) were used. For both normal maize starch (NMS) and waxy maize starch (WMS) reacted with POCl₃, the trends were generally the same, with apparent relative degrees of crosslinking indicated to be CL-Enz = CL > Enz-CL, but the effects were greater with NMS and there were differences when different concentrations of reagent were used. The basic trends were the same when potato starch was used in the same experiments. Crosslinking with STMP was done both in the presence and the absence of sodium sulfate (SS). Both with and without SS and with both NMS and WMS, the order of indicated crosslinking was generally the same as found after reaction with POCl₃, with the indicated swelling inhibition being greater when SS was present in the reaction mixture. Examination of the maize starches with a protein stain indicated that channel protein was removed by treatment with thermolysin when the proteinase treatment occurred before crosslinking with either POCl₃ or STMP, but only incompletely or not at all if the treatment with the proteinase occurred after crosslinking. Because the crosslinking reactions were less effective when the protein was removed, the results are tentatively interpreted as indicating that they involved protein molecules, although there may not be a direct relationship.     

烘烤条件对烟叶叶绿体淀粉粒超微结构变化的影响

以津巴布韦烤烟KRK26品种中部烟叶为实验材料,观察不同烘烤条件对烤烟KRK26中部烟叶叶绿体淀粉粒超微结构的影响变化。结果表明:(1)低温低湿条件下,烟叶叶绿体淀粉粒于烘烤36～48 h发生破裂;(2)中温中湿条件下,烟叶叶绿体淀粉粒于烘烤24～36 h发生破裂;(3)中温高湿条件下,烟叶叶绿体淀粉粒于烘烤12～24 h发生破裂。由此可见,在实际生产中为了降低成品烟叶中淀粉的含量,最适合采用中温高湿烘烤条件。     

Nitric oxide induces monosaccharide accumulation through enzyme S‐nitrosylation

Nitric oxide (NO) is extensively involved in various growth processes and stress responses in plants; however, the regulatory mechanism of NO‐modulated cellular sugar metabolism is still largely unknown. Here, we report that NO significantly inhibited monosaccharide catabolism by modulating sugar metabolic enzymes through S‐nitrosylation (mainly by oxidizing dihydrolipoamide, a cofactor of pyruvate dehydrogenase). These S‐nitrosylation modifications led to a decrease in cellular glycolysis enzymes and ATP synthase activities as well as declines in the content of acetyl coenzyme A, ATP, ADP‐glucose and UDP‐glucose, which eventually caused polysaccharide‐biosynthesis inhibition and monosaccharide accumulation. Plant developmental defects that were caused by high levels of NO included delayed flowering time, retarded root growth and reduced starch granule formation. These phenotypic defects could be mediated by sucrose supplementation, suggesting an essential role of NO‐sugar cross‐talks in plant growth and development. Our findings suggest that molecular manipulations could be used to improve fruit and vegetable sweetness.