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。     

灌浆成熟期温度对水稻籽粒淀粉合成关键酶活性及品质的影响

 选用蒸煮食味品质不同的3个粳稻品种，利用温室高温和自然常温，研究了灌浆成熟期温度对水稻籽粒淀粉合成关键酶活性及蒸煮食味品质的影响。结果表明，灌浆成熟期高温条件下，水稻籽粒蛋白质含量提高，直链淀粉含量和味度值降低，劣质品种提高或降低的程度大于优质品种；RVA谱特性对灌浆成熟期温度的反应因品种和特性而异；灌浆过程中，籽粒ADPG焦磷酸化酶、可溶性淀粉合成酶和淀粉分支酶活性随灌浆进程，酶活性逐渐增加，达到峰值以后，酶活性又逐渐下降，呈单峰曲线，但不同品种酶活性达到峰值的时间和同一时期的酶活性大小有差异；ADPG焦磷酸化酶和可溶性淀粉合成酶的活性表现对温度的影响反应较为迟钝，而淀粉分支酶活性表现对温度变化的反应较为敏感，温度过高过低都降低该酶活性。     

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.     

水稻杂交后代灌浆成熟期籽粒淀粉合成关键酶和谷氨酰胺合成酶活性变化的初步研究

 以东农423和藤系180为试材,籽粒直链淀粉和蛋白质含量为选择指标,通过逐代的定向选择形成了遗传背景相近且直链淀粉和蛋白质含量有显著差异的杂种后代,并对水稻灌浆成熟过程中籽粒ADPG焦磷酸化酶、可溶性淀粉合酶、淀粉分支酶、谷氨酰胺合成酶活性变化进行了初步研究。高直链淀粉含量杂交后代的籽粒ADPG焦磷酸化酶、可溶性淀粉合酶、淀粉分支酶活性峰值显著或极显著高于低直链淀粉含量后代,而且在籽粒灌浆前期蛋白质含量高的后代籽粒谷氨酰胺合成酶活性显著或极显著高于蛋白质含量低的后代。因此,通过直链淀粉和蛋白质含量的连续定向选择可以显著提高或降低灌浆过程中的籽粒碳氮代谢关键酶活性。     

小麦籽粒淀粉合成动态及其相关酶活性的研究

为了研究小麦籽粒淀粉形成机理与调控技术,选取2个小麦品种,对小麦胚乳发育期间籽粒中直、支链淀粉的积累动态及淀粉合成代谢的几个关键酶——ADPG焦磷酸化酶(ADPG-PPase)、UDPG焦磷酸化酶(UDPG-PPase)、可溶性淀粉合成酶(S-STS)、束缚态淀粉合成酶(B-STS)与淀粉分支酶(Q-酶)——的活性变化进行了分析。研究结果表明,在小麦籽粒灌浆过程中,直、支链淀粉几乎是同步积累的,不同品种的淀粉积累形成差异表现在两者的相对积累比率上。小麦籽粒发育过程中直链淀粉的含量变化呈“S”形曲线;支链淀粉的含量较直链淀粉含量上升略快。ADPG-PPase、UDPG-PPase、S-STS、B-STS、Q-酶的活性均与淀粉积累速率呈正相关。     

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。     

灌溉对弱筋小麦豫麦50籽粒淀粉积累及其相关酶活性的影响

为了探明灌溉对淀粉积累及其相关酶活性的影响规律,在大田条件下,以弱筋小麦豫麦50为材料,研究了三种灌溉方式(W1:拔节期灌水一次;W2:拔节期和孕穗期各灌水一次;W3:拔节期、孕穗期和灌浆期各灌水一次.每次灌水定额750 m3/ha)下弱筋小麦淀粉及其相关酶活性的变化规律.结果表明,弱筋小麦灌浆中后期和成熟期籽粒直链淀粉、支链淀粉、总淀粉积累速率均表现为W3>W2>W1.成孰期籽粒淀粉支/直比例表现为W3＞W2＞W1.成熟期籽粒淀粉支/直比例表现为W3＜W2＜W1.孕穗期和灌浆期增加灌水提高了灌浆中后期旗叶和籽粒中蔗糖含量、蔗糖合成酶(SS)活性、蔗糖磷酸合成酶（SPS）活性,提高了灌泺中后期籽粒中可溶性淀粉合成酶(SSS)活性和束缚态淀粉合成酶(GBSS)活性.说明增加灌水使弱筋小麦旗叶蔗糖合成能力强,促进源器官蔗糖向库中运输,保证籽粒库中糖源的充分供应,有利于籽粒淀粉的合成和积累.     

施磷量对弱筋小麦扬麦9号籽粒淀粉合成和积累特性的调控效应

以弱筋小麦扬麦9号为材料,在缺磷土壤（速效磷含量4．1mg／kg）上进行施磷量试验,研究施磷量对小麦籽粒淀粉合成、积累及相关酶活性的影响。结果表明。在施磷（P2O5）0～108kg／ha范围内,增加施磷量,籽粒直链淀粉、支链淀粉、总淀粉积累量、积累速率上升,旗叶蔗糖磷酸合成酶（SPS）活性和蔗糖含量提高,籽粒蔗糖合成酶（SS）活性增强。籽粒蔗糖含量提高。籽粒ADPG焦磷酸化酶（AGPP）、可溶性淀粉合成酶（ssS）、束缚态淀粉舍成酶（GBSS）活性提高,成熟籽粒直链淀粉、支链淀粉、总淀粉含量下降。施磷量超过108kg／ha后,直链淀粉、支链淀粉、总淀粉积累量、积累速率及蔗糖含量、SPS、SS、AGPP、SSS、GBSS酶活性呈下降趋势。     

木薯内源ABA含量与块根淀粉积累关系研究

以淀粉含量不同的木薯品种‘辐选01’和‘华南124’为材料,通过测定木薯内源脱落酸(ABA)含量、淀粉积累过程中的关键酶活性以及淀粉积累量,探讨ABA含量与块根淀粉积累的关系。结果表明:不同淀粉含量的木薯品种其内源ABA含量存在差异,尤其在生育后期表现尤为明显;淀粉含量高的品种叶片、茎秆和块根的ABA含量、块根腺苷二磷酸葡萄糖焦磷酸化酶(AGPpase)、蔗糖磷酸合成酶(SPS)、可溶性淀粉合成酶(SSS)及淀粉分支酶(SBE)的活性高于淀粉含量低的品种;结果表明,叶片ABA含量与块根的腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)、可溶性淀粉合成酶(SSS)及淀粉分支酶(SBE)活性呈极显著正相关,与蔗糖磷酸合成酶(SPS)活性呈显著正相关。茎秆ABA与腺苷二磷酸葡萄糖焦磷酸化酶(AGPpase)呈显著正相关,与可溶性淀粉合成酶(SSS)以及淀粉分支酶(SBE)的活性呈极显著正相关;块根ABA含量与块根腺苷二磷酸葡萄糖焦磷酸化酶(AGPpase)、可溶性淀粉合成酶(SSS)活性呈极显著正相关,与蔗糖磷酸合成酶(SPS)活性呈现正相关,与块根淀粉分支酶(SBE)活性呈极显著负相关。茎叶、块根ABA含量与块根淀粉积累均呈现极显著正相关。可见,木薯内源ABA在块根淀粉积累中有重要调节作用。本研究为高产、高淀粉木薯品种的选育与栽培提供理论支持和实践指导。      

Response of Rice Starch Synthesis to Night Temperature Changes

【Objective】To clarify the effect of night temperature changes on rice starch accumulation, and to explore circadian changes of physiological characteristics of rice amylose/amylopectin formation at various night temperatures.【Method】High-quality japonica rice ‘Zhehexiang 2’ was subjected to three night temperature gradients of 31℃/20℃ (LT), 31℃/24℃ (NT), and 31℃/28℃ (HT) at the beginning of grain ripening stage, and the amylose and amylopectin contents, the key enzyme activities involved in amylose and amylopectin formation and the expression of related genes were measured at noon and midnight. 【Result】 The results showed that 1) compared with NT, LT and HT treatments significantly reduced grain weight and starch accumulation, LT and HT both reduced amylopectin content and increased amylose content, meanwhile the effect of HT was greater than LT. LT and HT treatments decreased grain pasting temperature and gel consistency, and had a significant influence on branched chain length. 2) The net photosynthetic rate of leaves under LT and HT presented no significant difference compared to NT, but LT and HT significantly reduced the accumulation of non-structural carbohydrates, meanwhile down-regulated the expression level of sucrose transporter genes OsSUT1, OsSUT2, and OsSUT4 both at noon and midnight. 3) LT and HT treatment reduced sucrose hydrolysis-related enzyme activities, meanwhile promoted starch hydrolase activities, resulting in increased soluble sugar contents, sugar utilization in grain was blocked. 4) Compared with NT, the adenosine diphosphate glucose content showed a downward tendency during the day and a rising trend at night under the treatment of LT and HT, which presented that the accumulation and utilization of adenosine diphosphate glucose were inhibited. And the granules bound starch synthetase activity were significantly reduced under LT and HT compared to NT with the prolongation of the treatment, and the enzyme activity at daytime was significantly influenced by temperature changing at night. 5) Compared with NT, LT and HT reduced the activities of night-time amylopectin synthesis-related enzymes and inhibited the expression of night-time related genes, which retarded formation of amylopectin, but the enzyme activities related to amylopectin synthesis was not significantly influenced by night temperature changing. 【Conclusion】High night temperature had a less effect on starch accumulation than low night temperature. High or low night temperature inhibited sucrose transport and metabolism, resulting in declined starch accumulation. The retarding of amylopectin formation was the main reason for the increase of relative content of amylose at high or low night temperature. Night temperature changes directly affected the metabolic process of starch formation at night, but the daytime activities of amylose-related enzymes were affected by night temperature changes, while the daytime activities of amylopectin-related enzymes were not significantly affected by night temperature changes.     

CPPU和PP333对杂交稻3个淀粉合成酶活性和米质的影响

在抽穗期和抽穗期后12d对两系杂交水稻培杂青珍喷施CPPU[N-(2-氯－4－吡啶基）－N'－苯基脲]和PP333（多效唑）溶液。结果发现，CPPU和PP333能提高籽粒的可溶性淀粉合成酶（SSS）、结合性淀粉合成酶（GBSS）和淀粉分支酶（SBE）活性，其增加以SSS和SBE明显高于GBSS，而GBSS活性具有相对的稳定性。同时，能提高精米率、整精米率和胶稠度，而降低垩白粒率、垩白度和直链淀粉含量，有利于改良米质。其中，以抽穗期用质量浓度为10mg/L的PP333溶液喷60ml/m^2 抽穗期后12d用质量浓度为2mg/L的CPPU溶液喷施75ml/m^2的处理对促进SSS、SBE和GBSS活性提高与改良品质的作用最大。     

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。     

水稻淀粉合成对夜温变化的响应

目的 探究夜温变化对水稻淀粉形成的影响及其生理机制【方法】以优质软米浙禾香2号为材料,在灌浆初期设置31℃/20℃ (LT)、31℃/24℃ (NT)、31℃/28℃ (HT)3个夜间温度模式,测定其直链淀粉和支链淀粉含量及合成关键酶活性及相关基因的表达。结果 1)与NT相比,LT和HT处理显著降低粒重和淀粉积累,降低糊化温度和胶稠度,并影响支链淀粉链长,降低支链淀粉含量,提高直链淀粉含量,HT的影响要大于LT;2) LT和HT处理对白天叶片净光合速率的影响不显著,但显著降低籽粒中非结构性碳水化合物积累,抑制蔗糖转运基因OsSUT1、OsSUT2和OsSUT4在夜间和白天表达;3) LT 和HT处理降低夜间和白天蔗糖水解相关酶活性,增加淀粉水解酶活性,导致可溶性糖含量升高,籽粒中糖利用受阻;4)与NT相比,LT和HT处理下腺苷二磷酸葡萄糖含量呈现白天降低而夜晚升高的趋势,腺苷二磷酸葡萄糖积累及利用受到抑制,颗粒结合淀粉合酶活性随处理时间延长而显著降低,且白天酶活性也受夜间温度的影响;5)与NT相比,LT和HT处理降低了夜间支链淀粉合成相关酶活性,抑制了夜间相关基因的表达,导致支链淀粉合成受阻,但对白天酶活及相关基因表达的影响不大。结论 夜间高温对淀粉积累的影响要大于夜温降低,夜间高温/低温抑制全天蔗糖转运及代谢,进而抑制淀粉积累;支链淀粉合成受阻是导致直链淀粉相对含量升高的主要原因,直链淀粉合成相关酶活性(白天)受夜温变化影响,而支链淀粉合成相关酶活性(白天)受夜温变化的影响不显著。     

Relationship Between Variation in Activities of Key Enzymes Related to Starch Synthesis During Grain Filling Period and Quality of Eating and Cooking in Rice

Eating or cooking quality is one of the important quality of rice. Amylose content, RVA properties and taste meter value are three important indexes for evaluating cooking and eating quality of rice, which are determined by the chemical and physical com- …     

白粉病对小麦品种西农979籽粒淀粉合成关键酶基因表达的影响

为了揭示白粉病对花后小麦籽粒淀粉合成的影响机制,以小麦品种西农979为材料,利用实时荧光定量PCR技术研究白粉病不同发病程度对小麦籽粒淀粉合成相关酶基因表达的影响。结果表明,随着感病程度的增加,小麦籽粒的腺苷二磷酸葡萄糖焦磷酸化酶基因AGPase、淀粉分支酶基因SBE和可溶性淀粉合成酶基因SSS的表达均被抑制,其酶活性下降;束缚态淀粉合成酶I基因GBSSⅠ的表达量和酶活性均高于对照;去分支酶基因DBE的表达量与对照相比没有明显变化,但其酶活性在病害高峰期高于对照;支链淀粉含量和总淀粉含量显著降低,而直链淀粉含量增加。由此可知,白粉病通过改变籽粒淀粉合成相关酶基因的表达及活性而影响淀粉的积累。     

Effect of Temperature at Grain Filling Stage on Activities of Key Enzymes Related to Starch Synthesis and Grain Quality of Rice

Three japonica rice varieties with different cooking and eating quality were grown at high temperature in the greenhouse and natural field. Effects of temperature at the grain filling stage on these varieties were investigated in terms of the activities of key enzymes related to starch synthesis and cooking and eating quality of rice grain. The high temperature at the grain filling stage increased protein content, and decreased amylose content and taste meter value of rice; inferior grain quality varieties showed a greater magnitude of the increase or decrease than the superior ones. Reaction of rapid visco analyser profiles to the temperature varied with rice varieties. The activities of adenosine diphosphoglucose pyrophosphoryiase （AGPP）, soluble starch synthase （SSS） and starch branching enzyme （SBE） gradually increased to a peak value, and thereafter declined as grain filling progressed. Enzyme activities in different varieties differed in a same filling stage, and also in the time when the enzyme activity reached a maximum. AGPP and SSS were insensitive to the environmental temperature, but SBE was comparatively sensitive to the temperature, and its activity declined when temperature was too high or too low.     

Characterization of the Difference of Starch Branching Enzyme Activities in Normal and Low-Amylopectin Maize during Kernel Development

In order to determine the reasons for the differences in structure between starch from a normal and a low-amylopectin maize variety the activities of all the enzymes in the committed pathway of starch synthesis were studied throughout kernel development. Levels of ADP glucose pyrophosphorylase and starch synthase activity were found to be broadly similar between the two varieties but the low-amylopectin starch (LAPS) maize variety showed dramatically reduced starch branching enzyme activity, with an almost total absence of the branching enzyme II isoform. Scanning electron microscopy showed a significant alteration in the morphology of the starch granules of the low-amylopectin maize. The results suggest that the increased amylose and the reduction of high molecular weight amylopectin in the LAPS starch results from the absence of the branching enzyme II isoform. This evidence supports the theory that the different branching enzyme isoforms contribute separately to the synthesis and final structure of amylopectin.     

氮钾对杂交水稻B优827籽粒淀粉含量及淀粉合成酶活性的影响

以优质杂交籼稻B优827为材料,通过施用不同水平的氮、钾肥,并在B优827灌浆时段测定籽粒的直链淀粉、总淀粉含量以及淀粉合成酶的活性,分析氮、钾对水稻灌浆过程中籽粒淀粉积累、淀粉合成关键酶活性的影响,以及直链淀粉的积累与淀粉合成关键酶活性间的相关性。B优827的直链淀粉含量在开花后20 d内呈线性增加,开花20 d后有所下降;可溶性淀粉合成酶活性变化呈单峰曲线,开花后12 d酶活性达到了最高值,以后随天数增加而迅速降低;淀粉粒结合型淀粉合成酶活性变化呈单峰曲线,开花后15 d酶活性达到最高值,开花后15 d籽粒直链淀粉含量也接近最高值;灌浆中后期可溶性淀粉合成酶（SSS)、淀粉粒结合型淀粉合成酶（GBSS)与直链淀粉含量呈现出显著的正相关关系。增施氮肥可以提高SSS和GBSS活性,施钾肥在生育前期提高SSS和GBSS活性,后期抑制两者的活性;氮肥和钾肥均有促进淀粉积累的作用,但氮肥施用量过高时会抑制淀粉的积累。适当控施氮肥、增施钾肥是提高B优827籽粒产量的有效途径。     

水稻糖质胚乳突变体Sug-11籽粒灌浆过程的淀粉合成关键酶活性及其与淀粉理化特性关系

以水稻糖质胚乳突变体Sug-11与其野生型对照中花11为材料,通过对两者籽粒中可溶性总糖、蔗糖含量和淀粉含量以及有关淀粉品质理化指标的比较,结合籽粒灌浆过程中糖类物质含量、淀粉合成代谢关键酶活性和相关同工型基因转录表达水平的动态测定,从籽粒淀粉合成代谢角度,对水稻糖质突变体Sug-11的籽粒糖类含量变化和千粒重下降的生理原因进行了分析。结果表明,Sug-11糖质突变体与其野生型在灌浆初期的可溶性糖和蔗糖含量差异并不明显,随着籽粒灌浆进程,两者间的籽粒糖分含量差异在灌浆中后期逐步趋于明显;与野生型相比,Sug-11糖质胚乳突变体的稻米直链淀粉含量和直链淀粉碘蓝值显著下降,而淀粉溶解度和支链淀粉碘蓝值则显著升高,糖质胚乳突变对稻米淀粉的理化特性也产生了明显的影响;在籽粒淀粉合成代谢的几个关键酶中,Sug-11糖质突变体籽粒中的DBE活性及其在灌浆过程中的动态变化与其野生型存在明显差异,揭示了胚乳糖质突变体Sug-11籽粒中淀粉积累减少、糖分含量增加主要是由籽粒灌浆中后期的PUL转录表达水平和DBE活性的大幅下降所引起的,而Sug-11的籽粒灌浆不良和千粒重下降等现象,则与其ADPGase活性在籽粒灌浆前期的显著下降存在一定的联系。     

氮肥对水稻胚乳淀粉品质、相关酶活性及基因表达量的影响

【目的】旨在为阐明灌浆成熟期氮素营养对水稻淀粉品质影响机理以及建立优质高产水稻栽培技术提供理论依据。【方法】选用4个籽粒直链淀粉含量差异显著的粳稻品种,通过盆栽试验研究氮素营养对稻米淀粉组分和蛋白质含量及稻米蛋白质水解对淀粉黏滞特性的影响,并分析氮素营养对灌浆过程中籽粒蔗糖合酶(SuSy)、蔗糖磷酸合酶(SPS)、蔗糖酸性转化酶(AI)活性及OsGBSSⅠ、OsISAⅠ、OsSBEⅠ、OsSBEⅡ基因转录表达量的影响。【结果】结果表明,籽粒支链淀粉含量对氮素营养很敏感,灌浆成熟期氮素营养能改变籽粒淀粉组分含量;施氮条件下,高直链淀粉含量品种蒸煮食味品质下降更加明显,去除稻米蛋白质可明显提高稻米黏滞特性,蛋白质对淀粉黏滞特性的影响很大;增加灌浆成熟期氮素营养能显著或极显著提高籽粒SuSy和AI活性,显著抑制籽粒SPS活性;灌浆成熟期氮素营养能改变灌浆不同时期籽粒OsGBSSⅠ、OsISAⅠ和OsSBEⅡ基因转录表达量,以致灌浆过程中这些基因的转录表达量变化动态发生改变,但OsSBEⅠ基因转录表达量不因氮素营养而发生改变;受氮素营养的影响,灌浆起始期籽粒OsGBSSⅠ基因表达量明显上调,而灌浆中后期明显下调;氮素营养明显抑制灌浆成熟期籽粒OsISAⅠ基因和灌浆中后期的OsSBEⅠ基因转录表达,显著提高灌浆前期和中期的籽粒OsSBEⅠ基因转录表达量;氮素营养能抑制灌浆起始期籽粒OsSBEⅡ基因的转录表达,而提高灌浆中后期的基因转录表达。【结论】灌浆成熟期氮素营养除了通过蛋白质含量对淀粉品质产生影响外,还通过调控淀粉合成相关的酶活性和基因表达量等生理环节对淀粉含量和精细结构起作用,最终改变稻米黏滞特性和食味品质。