Changes in Activities of Key Enzymes for Starch Synthesis and Glutamine Synthetase in Grains of Progenies from a Rice Cross During Grain Filling

The progenies differed in amylose and protein contents in grains, which derived from a rice cross, Dongnong 423×Toukei 180, were used to study changes in the activities of ADP-glucose pyrophosphorylase （AGPP）, soluble starch synthetase （SSS）, starch branching enzyme （SBE） and glutamine synthetase （GS） in rice grains during grain filling. The activities of AGPP, SSS and SBE gradually increased and then declined as a single-peak curve with the process of grain filling in the progenies with high and low amylose contents in grains. The progenies with high amylose content peaked earlier in the AGPP, SSS and SBE activities and had higher AGPP, SSS and SBE activities at the early grain filling stage than those with low amylose content. The GS activity peaked earlier and was higher at the late stage of grain filling in the progenies with high protein content than in those with low protein content. It is suggested that the activities of key enzymes for starch synthesis and glutamine synthetase could be changed in oriented breeding for amylose and protein contents in grains.

Source-Sink and Grain-Filling Characteristics of Two-Line Hybrid Rice Yangliangyou 6

With two-line hybrid rice Yangliangyou 6 （YLY6） and Liangyoupeijiu （LYPJ） and three-line hybrid rice Shanyou 63 （SY63） as materials, the source, sink and flow characteristics in association with grain filling were investigated. The seed-setting rate, grain filling degree and grain yield of YLY6 and SY63 were significantly higher than those of LYPJ. The export and transformation percentages of the matter in culms and sheaths of YLY6 and SY63 were significantly higher than those of LYPJ. Activities of sucrose synthase, adenosine diphosphoglucose pyrophosphorylase, starch synthase and starch branching enzyme in grains were higher for YLY6 and SY63 than for LYPJ, and were very significantly correlated with maximum grain filling rate, mean grain filling rate, grain filling degree and grain weight. The spikelet number, grain yield and total sink load per area of vascular bundle and phloem of YLY6 and SY63 were significantly smaller than those of LYPJ, and the greater the load, the lower seed-setting rate and the poorer grain filling. The transportation rate per area phloem of YLY6 was greater than that of LYPJ or SY63. The results suggest that YLY6 possesses strong source, great sink activity and efficient flow, which lay a physiological base for its high seed-setting rate and good grain filling.

两系杂交稻扬两优6号源库特征与结实特性的分析

以两系杂交稻扬两优6号和两优培九及三系杂交稻汕优63为材料,研究了源、库、流特征及其与籽粒充实的关系。扬两优6号和汕优63的结实率、籽粒充实度和产量明显高于两优培九;扬两优6号和汕优63茎鞘物质输出率和转换率显著高于两优培九;扬两优6号和汕优63籽粒中蔗糖合成酶、腺苷二磷酸葡萄糖焦磷酸化酶、淀粉合成酶和淀粉分支酶的活性显著高于两优培九,且上述各酶的活性与籽粒最大灌浆速率、平均灌浆速率、谷粒充实度和粒重呈极显著的正相关;扬两优6号和汕优63的单位维管束和韧皮部的颖花负荷、现实产量负荷、总库容负荷显著小于两优培九,且负荷越大的组合结实率就越低,充实度也就越差。扬两优6号单位面积韧皮部的物质转运速率显著高于两优培九和汕优63。表明扬两优6号具有源足、库强、流畅的特点,这是它结实率高和籽粒充实度好的生理基础。

亚种间杂交稻发育籽粒中ATP酶活性及其调节

以籼／粳亚种间杂交稻组合及其亲本为材料，研究了灌浆期籽粒中ATP酶活性变化动态及其激素与多胺调控。结果表明：花后3～18d籽粒中的ATP酶活性，强势粒明显高于弱势粒，物质运转率或籽粒充实好的组合（亲本）高于物质运转率或籽粒充实差的组合(亲本)，灌浆初期籽粒中的ATP酶活性与谷粒充实率、受精籽粒粒重和物质运转率呈极显著正相关；开花后2d分别喷施低浓度ABA(0．05mmol·L(-1))、IAA(0．2mmol·L(-1))、亚精胺(1mmol·L(-1))和精胺(0．5mmol·L(-1))可明显提高籽粒中的ATP酶活性、物质运转率和谷粒充实率。

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。

籼粳杂交稻籽粒库活性与其充实关系的研究

以两个籽粒充实程度不同的籼粳亚种间杂交稻 PC31 1×早献党 1 8(充实差 )和测 0 3×扬稻 4号 (充实好 )为材料 ,研究两组合的强、弱势粒发育过程中籽粒库活性与其充实之间的关系。结果表明 :( 1 )充实好的亚杂组合强、弱势粒干重、淀粉积累速率都相应高于充实差的亚杂组合 ,两组合的强、弱势粒灌浆特性均表现异步型特征 ;( 2 )在灌浆早期 ,两亚杂组合强、弱势粒胚乳中蔗糖含量都比较高 ,且测扬要明显高于 P早 ;在籽粒发育后期 ,蔗糖含量又有回升 ,尤其是 P早弱势粒 ;( 3)充实好的亚杂组合强、弱势粒胚乳蔗糖合成酶、腺苷二磷酸葡萄糖焦磷酸化酶和淀粉合成酶活性都相应高于充实差的亚杂组合 ,尤以弱势粒表现更明显 ,3种酶活性变化都与淀粉积累曲线一致 ;( 4 )胚乳细胞质中低 Pi含量、高 ATP水平有利于淀粉体合成淀粉。