Gene Expression of Enzymes for Starch and Sucrose Metabolism and Transport in Leaf Sheaths of Rice (Oryza sativa L.) during the Heading Period in Relation to the Sink to Source Transition

Abstract

Leaf sheaths of rice plants are known to temporarily accumulate starch prior to heading, which is subsequently remobilized and transported into the panicle after heading. We investigated the time course for both carbohydrate content and steady state mRNA levels of enzymes related to starch and sucrose metabolism in the rice leaf sheath (Oryza sativa L. cv. Nipponbare). Leaf sheaths from the second leaf below the flag leaf accumulated high levels of starch before heading but they rapidly decreased after heading. In contrast, the flag leaf sheath did not accumulate as much starch. In the second leaf sheath, the mRNA levels of enzymes involved in starch synthesis, ADP glucose pyrophosphorylase (EC 2. 7. 7. 27), soluble starch synthase (EC 2. 4. 1.21) and branching enzyme (EC 2. 4. 1. 18) were high before heading, which coincided with rapid accumulation of starch. The mRNA levels of sucrose synthesis enzymes, cytosolic FBPase (EC 3. 1. 3. 11) and sucrose phosphate synthase (EC 2. 4. 1. 14), and the sucrose transporter (OsSUTI) increased at the time of heading, which was largely coincident with a decrease in the mRNA levels of starch synthesis enzymes. In the flag leaf sheaths, changes in mRNA levels of starch synthesis enzymes were not pronounced, however mRNA levels of sucrose synthesis enzymes and the sucrose transporter showed a clear increase throughout the heading period. The different characteristics observed between the two leaf sheaths will be discussed in relation to the sink to source transition.     

棉花群体叶面积载荷量与产量关系及对源的调节效应研究

通过对棉花单位叶面积负载的生殖器官量的研究结果表明：较高的叶面积载荷量［以单位叶面积负载的果节数（个／ｍ２叶）、结铃数（个／ｍ２叶）及生殖器官干重（ｋｇ／ｍ２叶））能够促进棉花群体叶片光合强度提高和养分向棉铃输送增多，因而群体成铃数增多，产量提高。同时由剪叶、疏蕾试验揭示了，当群体叶面积系数控制在适宜范围内，可通过提高叶面积载荷量使产量进一步上升，群体叶面积系数过大时，通过减少叶面积，提高叶面积载铃量可以使产量增加。而当叶面积过小时，虽叶面积载荷量增大，但终因光合面积太小，产量下降，因此叶面积载荷量可作为反映棉花群体源库是否协调及改进栽培技术的依据。     

萝卜肉质根膨大过程中库活性的变化

以根冠比不同的3个萝卜品种为材料,研究了萝卜肉质根的生长动态和肉质根膨大过程中源-库活性的变化.结果表明:播种后14～21 d肉质根开始膨大,并在播种28d后进入快速膨大期;叶片的快速生长期先于肉质根.3个品种其根冠比(鲜质量)存在非常明显的差异.其中‘短叶13'在播种后35 d,其根冠比即达到1以上;至播种后56 d其根冠比高达4.7,而‘叶用萝卜'根冠比始终小于1.源活性在播种后14～21 d达到最大,之后逐渐下降,但‘叶用萝卜'源活性在播种后21～28 d仍维持较高的水平;库活性在播种后28 d(‘短叶13'和‘叶用萝卜')或35 d(‘白玉春')内持续快速提高,之后则呈下降趋势.在整个生长过程中,‘短叶13'的源活性始终低于其它两个品种,而其库活性和地下部干重并不低于其它2个品种.     

穗重差异型两系法杂交水稻灌浆期若干源库指标动态变化的比较

从单茎水平上比较了重、中、轻3种不同穗重型两系法杂交水稻灌浆期若干源库及其相互关系指标的动态差异.结果表明,相时于中、轻型两系法杂交稻,重型具有如下特点:单穗粒多、实粒数多、千粒重重、单茎库容量大;抽穗后叶绿素含量前期高、中期衰减慢、后期较迅速;籽粒灌浆速度快,持续期长;抽穗后前期比叶重大,后期持续缓慢衰减;粒叶比高、物粒比和颖花茎鞘重较低.     

Grain weight responses to post-anthesis spikelet-trimming in an old and a modern wheat under Mediterranean conditions

Average grain weight is a major yield component contributing to its variation, especially in Mediterranean regions where grain weight is frequently exposed to terminal stresses affecting grain growth. Most of the literature agrees that wheat grain growth is hardly limited by the source. However, no source–sink ratios studies seem to have been conducted in the Mediterranean region to determine to what degree wheat grain growth is actually limited by the source in these particular regions. We conducted two field experiments in Catalonia (north-eastern Spain), where an old cultivar (Anza) and a more recently released one (Soissons) were sown in a range of different nitrogen and water availabilities and sowing dates. This was to analyse the degree of source limitation for grain growth. Sink size was modified by removing half of the spikelets c. 10 days after anthesis, virtually doubling the availability of assimilates per grain effectively growing.

Trimming the spikes did not produce significant changes in grain growth rate or duration of grain filling. Consequently, grain weight did not respond noticeably to the reduction in sink demand and any eventual response has been far from representing a strong competition among grains during grain filling.     

结实期源库活性对稻米垩白度的影响

选择６个垩白差异明显的早籼稻品种为材料，分３期播种，使之在不同温度下灌浆结实。以结实期叶片含Ｎ量累积值为源活性指标，以籽粒灌浆有效含水量累积值为库活性指标，研究了稻米垩白度与结实期源库活性的关系。结果表明：①稻米垩白度在很大程度上决定于结实期源库活性的大小，其决定系数达０．８４～０．９６；②在不同播期（温度）下，库活性的变化大于源活性；③对稻米垩白度的影响，除浙辐３７为源活性大于库活性外，其余５个供试品种均为库活性大于源活性；④稻米垩白度与库活性呈极显著负相关，与源活性的相关性，垩白较大品种为显著负相关，垩白较小品种相关不显著     

植物生长物质对烟草源库的作用

概述了植物激素和烟用生长调节剂对烟草源库分化、源库发育、源库强度、源库质量以及源库转换的主要作用.一些植物生长调节剂对改善源烟叶性状和提高库烟叶质量具有显著效果.     

水稻氮素供需差与不同叶位叶片氮转运和衰老的关系

 采用去穗和疏花方法调节稻穗氮需求量 ,研究了水稻氮素供需差 (NSDB)对不同叶位叶片氮转运和衰老的影响。结果表明 ,在NSDB <0的条件下 (对照 ) ,植株上部 4张叶输出氮素 ,叶片正常衰老 ;随NSDB提高 ,顶部叶片尤其是顶 4叶的氮素输出显著减少 ,叶片MDA含量下降 ,SOD和CAT酶活力提高 ,上位叶与下位叶之间的叶色差缩小 ;当NSDB >0以后 (去穗 ) ,上部 4叶的氮积累量不仅未减少 ,相反还有显著的增加 ,叶片的衰老进程被延缓。研究证实顶 4叶叶色受氮素供需差的影响最大 ,当土壤供氮不能满足库需氮时 ,顶 4叶叶色浅于顶 3叶     

不同类型水稻品种的产量构成因素与产量的关系(英文)

[目的]研究不同类型水稻品种产量构成因素与产量的关系,为水稻高产栽培提供理论依据。[方法]以在四川成都地区应用较多的超级稻品种和非超级稻品种为试验材料,研究不同类型品种连续 3 年(2006~2008 年)在高产栽培条件下的产量表现,分析其产量构成因素与产量的关系。[结果]水稻的产量与穗数、穗粒数、结实率、千粒重关系密切,对于不同的品种类型,4个因素对产量的影响存在差异。在10.5~11.25 t/hm2的产量目标下,通过中小苗三角形条栽模式研究结果显示超级稻的产量与穗数、千粒重关系密切,同时,与穗粒数呈负相关,与结实率呈显著负相关。非超级稻品种的产量与穗数、穗粒数、结实率、千粒重均呈负相关关系,且与穗数、千粒重呈显著负相关。[结论]该研究明确了不同类型水稻品种的产量构成因素与产量的关系,为合理制订高产栽培措施、充分发挥超级稻的产量潜力、实现水稻大面积稳产高产奠定了基础。     

不同库容量粳稻调控因素初步分析

对沪郊2008-2009年区域试验的水稻晚粳品种进行了各性状与产量、库容量的相关统计分析和不同库容类型的水稻高产栽培调控因素筛选。结果表明:水稻的库容量与产量呈显著正相关(r=0.748):并明确了水稻品种不同库容量的主要调控因素,为不同库容类型水稻高产和大面积生产提供了科学的栽培调控策略。