具不同蛋白质含量水稻品种中天冬酰胺合成酶基因的表达

为研究水稻中氮同化与籽粒蛋白质合成可能的关系,本实验通过Northern杂交分析比较了氮同化关键酶一天冬酰胺合成酶基因(OsAS)在不同水稻品种中的表达特性.结果显示,OsAS基因在水稻不同组织及其不同发育时期中的表达水平不同,以发育种子中的表达量最高,叶鞘和叶片中相对较弱;在籽粒发育过程中OsAS基因的表达呈先升高后下降的趋势.具不同种子蛋白质含量水稻品种叶片中OsAS基因的表达水平存在显著差异,相关性分析显示在籼亚种或粳亚种不同品种内OsAS基因表达量与籽粒蛋白质含量可能存在一定的关联.     

水稻籽粒灌浆过程中蛋白质表达特性及其对氮肥运筹的响应

采用大田栽培的方式,研究了大穗型水稻金辉809籽粒灌浆过程中蛋白质的差异表达变化模式以及同一施氮量下不同的氮肥施用比例(总施氮量225 kg/hm2,基蘖肥:穗粒肥分别为7∶3和6∶4)对强弱势粒灌浆影响的分子机制。获得了水稻不同灌浆时段籽粒总蛋白的表达图谱,共发现32个在灌浆过程中发生显著差异表达的蛋白点,涉及籽粒的淀粉合成,能量代谢,激素信号转导,基因表达调节和抗逆响应等。在此基础上,进一步构建了不同灌浆发育时段水稻强弱势籽粒响应不同氮肥比例调控的蛋白表达图谱,结果发现强势籽粒响应氮肥调控出现差异表达的蛋白点有8个,而弱势籽粒有26个,可见强势籽粒灌浆具有更强的环境稳定性,相对地,弱势籽粒灌浆则易被环境所调节。在总施氮量不变的情况下,适当增加生育后期氮肥的施用量,有利于增强弱势籽粒中信号转导,促进相关基因的表达,提高物质调运与能量代谢速率,增强抗逆性,增强弱势籽粒的代谢水平,延长其灌浆时期,提升弱势籽粒活性和灌浆强度,增加结实率和千粒重,最终实现高产高效。研究结果对于进一步明确氮素调控水稻强弱势粒灌浆的分子生态特性具有重要的理论与实际意义。     

杂交水稻灌浆过程中籽粒充实的生理研究

杂交水稻在籽粒灌浆过程中,存在两个灌浆高峰期,籽粒中蔗糖含量增加的高峰出现在第一个灌浆高峰期;稻穗上,下部籽粒中ＵＤＰＧ焦磷酸化酶活性高峰出现的时期分别与群体籽粒两个灌浆高峰期基本一致;杂交水稻籽粒中的３－磷酸甘油酸磷酸酶活性高峰比常规稻的出现早。     

低温对水稻籽粒不同灌浆阶段的影响

低温对水稻籽粒灌浆影响的研究中,认为累积温度与籽粒灌浆有密切关系,但低温对水稻籽粒不同灌浆阶段影响的资料则很少。同样的累积温度由于温度影响的时期不同而产量大不相同。这使我们联想到低温对水稻籽粒不同灌浆阶段的影响可能是不同的。为此,我们进行了初步研究。     

优质早籼新品种农大228耐高温逼熟生理基础研究初探

灌浆期耐热性不同的早籼品种在细胞膜热稳定性及籽粒灌浆特性上存在明显差异.50℃热致死时间所表达的细胞膜热稳定性可以很好地反映出不同水稻品种灌浆期耐热性的强弱,农大228具有较好的细胞膜质量,是其耐高温逼熟的物质基础.农大228籽粒灌浆速率高而且灌浆期间变幅平稳,灌浆持续期较短是其耐高温逼熟的生理机制之一.     

优质早籼新品种农大228耐高温逼熟生理基础研究初探

灌浆期耐热性不同的早籼品种在细胞膜热稳定性及籽粒灌浆特性上存在明显差异。50℃热致死时间所表达的细胞膜热稳定性可以很好地反映出不同水稻品种灌浆期耐热性的强弱,农大228具有较好的细胞膜质量,是其耐高温逼熟的物质基础。农大228籽粒灌浆速率高而且灌浆期闻变幅平稳,灌浆持续期较短是其耐高温逼熟的生理机制之一。     

稻米直链淀粉含量的形成及其与灌浆结实期温度的关系

通过多类型品种的田间分期番种和人工气候箱控温处理等试验,对稻米直链淀粉含量（Ａｍｙｌｏｓｅ ｃｏｎｔｅｎｔ,简称ＡＣ）的形成动态变化特征及灌浆结实期温度的影响效应进行了分析。结果表明：水稻灌浆结实过程中稻米ＡＣ的形成动态变化过程叮嘱一次或二次曲线进行模拟,灌浆初期籽粒中的ＡＣ值很低,随之急剧上升,至２０～３０ｄ左右达到最大值,然后ＡＣ的变化基本趋于稳定;稻米ＡＣ的形成变化与籽粒于物质积累过程喑存在     

水稻不同品种对铅吸收、分配的差异及机理

为探究水稻不同品种对Pb吸收积累的差异及机理,以20个不同基因型水稻品种(系)为材料,采用盆栽方法,研究了Pb在水稻植株各器官中的分配及在籽粒中的分布．结果表明,不同品种间,Pb积累量存在显著差异,但品种间的这种差异与品种类型关系不明显;不同器官、不同生育时期,Pb积累量和积累速率不同;各器官Pb浓度按根、茎、叶、穗、籽粒的顺序大幅度下降,分配到籽粒中的Pb比例很低;根与茎,茎与叶片、穗(抽穗期)、籽粒Pb含量呈极显著负相关;根与叶、穗(抽穗期)、籽粒,叶与穗(抽穗期)、籽粒的Pb含量呈正相关,相关性大多达极显著或显著水平;不同品种抽穗期叶片与成熟期籽粒间的Pb含量达显著正相关;Pb在稻米加工各产物中的分布很不均匀,稻谷经脱壳及精加工1次(2min)后,精米Pb含量仅为籽粒总含Pb量的32．88％．     

聚糠萘水剂对黑龙江省不同积温带玉米籽粒灌浆的影响

2010和2011年在黑龙江省3个积温带(Ⅰ、Ⅱ、Ⅲ)上,以不同基因型玉米品种郑单958和丰单3号为试材,研究不同环境温度下外源植物激素复配剂聚糠萘水剂（PASP-KT-NAA,PKN）对玉米籽粒灌浆过程和产量的影响.结果表明： 从第Ⅰ积温带到第Ⅲ积温带,玉米灌浆期的温度呈降低趋势;平均最低气温分别为12.16、11.40和9.56 ℃,玉米籽粒灌浆中后期有效积温不足,平均最低气温低于16 ℃,严重影响玉米的灌浆过程.施用PKN处理提高了3个积温带玉米籽粒干物质积累和籽粒灌浆速率;延迟了丰单3号籽粒灌浆速率达峰值的时间（T_max）,提早了郑单958的T_max;提高了两品种籽粒灌浆速率最大时的生长量和籽粒最大灌浆速率;缩短了籽粒的灌浆活跃期.PKN处理明显提高了3个积温带下两玉米品种的产量,第Ⅲ积温带的郑单958和丰单3号产量分别比第Ⅰ、Ⅱ积温带高82%、5.1%和3.4%、0.8%.施用外源PKN有助于玉米利用有限的积温,提高籽粒灌浆速率,降低籽粒含水量,最终增加产量.     

结实期土壤水分亏缺影响水稻籽粒灌浆的生理原因

通过分析结实期土壤水分亏缺对水稻(Oryza sativa)籽粒中蔗糖向淀粉合成的生理代谢中关键酶活性及籽粒灌浆的调节作用, 探讨土壤水分亏缺影响水稻籽粒灌浆的生理机制。结果表明, 适度土壤水分亏缺诱导了灌浆高峰期(花后15-20天)水稻籽粒中蔗糖合成酶、腺苷二磷酶葡萄糖焦磷酸化酶、可溶性淀粉合成酶及淀粉分支酶活性的增加, 提高了籽粒灌浆中前期(花后10-20天)籽粒中淀粉积累速率和籽粒灌浆速率。但在灌浆后期(花后20-30天)籽粒中, 上述关键酶活性下降较快, 籽粒活跃灌浆期明显缩短, 灌浆前中期灌浆速率的增加不能完全补偿灌浆期缩短带来的同化物积累损失, 导致水分亏缺处理水稻籽粒充实不良, 结实率、籽粒重和产量显著降低。研究认为, 灌浆期土壤水分亏缺引起的灌浆后期籽粒中蔗糖向淀粉合成代谢中一些关键酶活性快速下降和籽粒内容物的供应不足是籽粒淀粉积累总量减少、粒重降低的主要生理原因。     

水稻和玉米幼苗的超弱生物光子发射比较研究

利用自制的超高灵敏度超弱生物光子发射（ultraweak biphoton emissions,UBE)二维图象系统观测比较了水稻（Orza sativaL.)和玉米（Zea maysL.)不同品种种子萌发过程中超弱生物光子发射的变化。发现普通饲料玉米（阳单82）和高杆水稻品种（金科占）的种苗及＋1叶的UBE分别比超甜玉米品种（穗甜1号、3号）和矮杆水稻品种（矮珍占）低,而前者的UBE衰减比后者要快,进一步证实超弱生物光子发射是十分灵敏的,且其差别的出现远远早于其它生物学指标,这种特性可能具有普遍性。     

光质对绿豆幼苗叶片超微弱发光及叶绿素含量的影响

以绿豆幼苗为试材,测定其叶片超弱发光(UBE)及叶绿素含量在不同光质条件下的变化,并探讨两者之间的关系.结果表明,生长在不同光质下绿豆幼苗叶片的UBE及延迟发光衰减参数1/P都随着其生长不断增强,且生长在白光下绿豆幼苗的UBE是生长在其他光质(红、黄、蓝、绿)下幼苗的2倍以上,而红光、黄光和绿光处理之间无显著差异;生长在白光下的绿豆幼苗叶片叶绿素含量显著高于红、黄、蓝、绿光处理幼苗,而红光和黄光处理又显著高于蓝光和绿光处理.研究发现,光质对绿豆幼苗叶片超弱发光和叶绿素含量影响相似,绿豆幼苗叶片超弱发光可能与叶绿体的发育和光合作用有关.     

Post-anthesis development of inferior and superior spikelets in rice in relation to abscisic acid and ethylene

The purpose of this study was to test the hypothesis that the interaction between abscisic acid (ABA) and ethylene may be involved in mediating the post-anthesis development of spikelets in rice (Oryza sativa L.). Two rice genotypes were field-grown, and the changes of ABA, ethylene, and 1-aminocylopropane-1-carboxylic acid (ACC) levels in spikelets during grain filling and their relationships with endosperm-division and grain-filling rates were investigated. The results showed that earlier-flowering superior spikelets exerted dominance over later-flowering inferior spikelets in endosperm cell-division and grain-filling rates. The two genotypes behaved the same. Later-flowering spikelets had higher levels of ethylene and ACC than earlier-flowering spikelets. The ethylene evolution rate was significantly and negatively correlated with the cell division and grain filling rates. By contrast to ethylene, later-flowering spikelets contained a lower ABA content/concentration and showed a low content ratio of ABA to ACC than earlier-flowering ones. The cell-division and grain-filling rates were significantly and positively correlated with both ABA contents and the ratio of ABA to ACC. Application of cobalt ion (inhibitor of ethylene synthesis) or ABA at an early grain-filling stage significantly increased endosperm cell division rate and cell number, grain-filling rate, and grain weight of inferior spikelets. Application of ethephon (an ethylene-releasing agent) or fluridone (an inhibitor of carotenoid synthesis) had the opposite effect. The results suggest that antagonistic interactions between ABA and ethylene mediate endosperm cell-division and grain-filling in rice. A higher ratio of ABA to ethylene in rice spikelets is required to maintain a faster grain-filling rate.     

生育前期遮光对水稻灌浆期剑叶生理特性及籽粒生长的影响

通过盆栽试验研究了生育前期（插秧至孕穗期）遮光对水稻分蘖、灌浆期剑叶生理特性、籽粒生长、产量及其构成因素的影响.结果表明：前期遮光使水稻分蘖数明显降低（降低26.72%）,齐穗期与成熟期发生延迟;遮光结束后,水稻灌浆期剑叶叶面积、可溶性糖含量分别比对照增加了33.86%和30.23%;每穗实粒数、千粒重、籽粒终极生长量、最大灌浆速率、平均灌浆速率分别比对照降低了8.65%、4.81%、9.74%、20.22%和19.13%;有效穗数与产量分别降低了25.26%和39.56%,差异显著;灌浆速率峰值的出现时间提前了1.66 d,实际灌浆时间延长了6.80 d.与弱耐荫水稻品种相比,耐荫品种灌浆前中期的剑叶叶绿素a、叶绿素b、叶绿素(a+b)含量增加,灌浆期的剑叶叶面积增加幅度大,蛋白氮、可溶性糖含量及叶绿素 a/b升高,籽粒终极生长量及千粒重接近对照,减产幅度相对较低.     

Grain filling of cereals under soil drying

Monocarpic plants require the initiation of whole-plant senescence to remobilize and transfer assimilates pre-stored in vegetative tissues to grains. Delayed whole-plant senescence caused by either heavy use of nitrogen fertilizer or adoption of lodging-resistant cultivars/hybrids that remain green when the grains are due to ripen results in a low harvest index with much nonstructural carbohydrate (NSC) left in the straw. Usually, water stress during the grain-filling period induces early senescence, reduces photosynthesis, and shortens the grain-filling period; however, it increases the remobilization of NSC from the vegetative tissues to the grain. If mild soil drying is properly controlled during the later grain-filling period in rice (Oryza sativa) and wheat (Triticum aestivum), it can enhance whole-plant senescence, lead to faster and better remobilization of carbon from vegetative tissues to grains, and accelerate the grain-filling rate. In cases where plant senescence is unfavorably delayed, such as by heavy use of nitrogen and the introduction of hybrids with strong heterosis, the gain from the enhanced remobilization and accelerated grain-filling rate can outweigh the loss of reduced photosynthesis and the shortened grain-filling period, leading to an increased grain yield, better harvest index and higher water-use efficiency.     

Increasing the abscisic acid level in maize grains induces precocious maturation by accelerating grain filling and dehydration

Elevated levels of abscisic acid (ABA) are closely associated with cereal grain filling under water deficit. However, grain dehydration during grain filling has received little attention. In this paper, three experiments with drought stress and exogenous ABA treatments were conducted to investigate the relationship between ABA and grain dehydration in maize (Zea mays L.) during the grain-filling period. The results indicated that exogenous ABA application and drought stress led to the same tendency of the grain ABA concentration, carbohydrate concentration and dehydration rate to increase but the moisture content to decrease. Moreover, the time to reach the maximum grain-filling rate was advanced, and the grain-filling period was shortened. In in vitro culture experiments, the sucrose-to-starch conversion was promoted, mainly influenced by sucrose synthase, ADP-glucose pyrophosphorylase (AGPase), and soluble starch synthase during the middle grain-filling stage, and the improvement in starch synthesis was possibly induced by AGPase. Correlation analysis showed that the ABA level was significantly negatively correlated with the moisture content and positively correlated with the starch level. A close and notably negative correlation was observed between the grain moisture content and starch level. In summary, adequate grain ABA promoted sucrose-to-starch conversion, shortened the duration of grain filling and accelerated grain dehydration, resulting in precocious grain maturation.     

Post-anthesis alternate wetting and moderate soil drying enhances activities of key enzymes in sucrose-to-starch conversion in inferior spikelets of rice

This study tested the hypothesis that a post-anthesis moderate soil drying can improve grain filling through regulating the key enzymes in the sucrose-to-starch pathway in the grains of rice (Oryza sativa L.). Two rice cultivars were field grown and two irrigation regimes, alternate wetting and moderate soil drying (WMD) and conventional irrigation (CI, continuously flooded), were imposed during the grain-filling period. The grain-filling rate and activities of four key enzymes in sucrose-to-starch conversion, sucrose synthase (SuSase), adenosine diphosphate-glucose pyrophosphorylase (AGPase), starch synthase (StSase), and starch branching enzyme (SBE), showed no significant difference between WMD and CI regimes for the earlier flowering superior spikelets. However, they were significantly enhanced by the WMD for the later flowering inferior spikelets. The activities of both soluble and insoluble acid invertase in the grains were little affected by the WMD. The two cultivars showed the same tendencies. The activities of SuSase, AGPase, StSase, and SBE in grains were very significantly correlated with the grain-filling rate. The abscisic acid (ABA) concentration in inferior spikelets was remarkably increased in the WMD and very significantly correlated with activities of SuSase, AGPase, StSase, and SBE. Application of ABA on plants under CI produced similar results to those seen in plants receiving WMD. Applying fluridone, an indirect inhibitor of ABA synthesis, produced the opposite effect. The results suggest that post-anthesis WMD could enhance sink strength by regulating the key enzymes involved, and consequently, increase the grain-filling rate and grain weight of inferior spikelets. ABA plays an important role in this process.     

早晚季不同耐光氧化特性水稻品种籽粒灌浆关键酶活性变化

选用光氧化敏感和不敏感的两大类型4个水稻品种研究早晚季耐光氧化反应特性与其稻米品质稳定性密切相关的生理生化原因.结果表明,耐光氧化反应特性强的适强光生态型水稻品种的平均灌浆速率(G_mean)、达最大灌浆速率时间(T_max.G)和达最大灌浆速率百粒重(W_max.G)等参数在早晚季灌浆结实期间保持相对稳定;而对光氧化敏感的弱光生态型品种佳禾早占以上参数的早晚季稳定性较差.比较早晚季籽粒灌浆充实过程中关键酶活性的变化结果可见,耐光氧化反应特性强的品种,灌浆速率高峰到灌浆终期ADPG-焦磷酸化酶和淀粉合成酶活性早晚季变异比耐光氧化反应特性弱的品种小,且耐光氧化反应特性强的品种灌浆高峰前后酶活性变异的幅度早晚季也较一致.