两优培九剑叶衰老过程光合膜功能及蛋白质复合物的变化

为探讨高产杂交稻两优培九在衰老过程中，剑叶光合膜蛋白质复合物的含量变化规律及其与光能吸收、转化、传递的关系，以大田栽培自然衰老剑叶为材料，利用活体叶绿素荧光动力学技术，并结合类囊体膜蛋白质复合物蓝绿温和胶电泳分析。结果表明，两优培九剑叶叶绿素含量、光合性能、类囊体膜蛋白稳定性等都在抽穗期达到顶峰，随后开始衰退，在扬花期、灌浆期尚保持较高水平，而进入籽粒成熟阶段衰退明显；随着衰老进程，光合膜蛋白质复合物有序非同步降解，稳定性为LHCII > PSIIcore > PSIcore > ATPase & Cyt b₆/f > LHCI；PSI和PSII蛋白和相应电子传递活性的稳定性及下降幅度差异较大；衰老过程叶绿素a/b的不断下降与相对于反应中心更稳定的捕光天线有关，剑叶生长后期LHCII维持高水平保持了叶片对光能的吸收，并可能在调节光系统间能量分布和协助过剩能量耗散中起重要作用。

Changes of Photosynthetic Membrane Function and Protein Complexes in Flag Leaves of Liangyoupeijiu during Leaf Senescence

The purpose of this study was to explore the content variation of thylakoid membrane protein complexes and its relationship with light absorption, transformation and transfer in flag leaves of high-yield hybrid rice Liangyoupeijiu during senescence. A rice cultivar, Liangyoupeijiu was grown in the field. Through chlorophyll a fluorescence transient, physiological and biochemical techniques, we studied the function of photosynthetic membrane. The content changes of thylakoid membrane protein complexes were also investigated by Blue-Native polyacrylamide gel-electrophoresis (BN-PAGE). The results showed that chlorophyll content, photosynthesis and thylakoid membrane protein content of flag leaves rose and peaked at heading stage, then began to decline. It still maintained a high level at flowering and filling stages, and the significant decline appeared untill the stage of milky and wax ripeness. The stability of protein complexes (i.e. inverse degradation rate) during leaf senescence showed an order of LHCII > PSIIcore > PSIcore > ATPase &; Cyt b₆/f > LHCI. Protein complexes and electron transport activity of PSIdeclined later but more quickly than those of PSII. The decreased chlorophyll a/b ratio could be explained by the relative enrichment of light-harvesting antenna to reaction center with leaf senescence. The stable LHCII kept the high level of absorbing energy in the late of flag leaf growth, which may play an important role in adjusting the energy distribution and dissipation during leaf senescence.