【作者】 王伟青；

【导师】 于文功；

【作者基本信息】 中国海洋大学 ， 水产品加工及贮藏工程， 2007， 博士

【摘要】 研究小麦旗叶在灌浆期间的光合作用有着重要意义。本文对小麦灌浆过程中旗叶的灌浆特征以及与光合作用的关系较为全面的研究:1.对五个小麦品种籽粒灌浆过程和灌浆速率的研究表明,千粒重符合Richards方程,呈S型曲线,都有一个快速灌浆时期(RGFP),从花后5 d进入快速灌浆时期,灌浆速率呈单峰曲线。2.灌浆期间叶绿素含量和chla/b存在着显著性相关。叶绿素含量变化随着灌浆的进行初期和中期变化不大,灌浆后期开始迅速下降,与光合速率的变化规律相似。Chl a/b也随着灌浆的进行呈下降趋势,但是它在灌浆初期有所上升.3.通过测定旗叶光系统II叶绿素荧光参数,结果说明衰老叶片中,光系统II与叶绿素含量和光合速率降低是同步的。衰老旗叶中叶绿素含量,饱和光合速率和叶绿素荧光的研究表明,灌浆初期和中期光系统II仍然有较完整的功能以继续有效的利用捕获的光能。4.在灌浆过程中,抗坏血酸含量以及其与脱氢抗坏血酸比值逐渐增加,谷胱甘肽含量逐渐降低,说明在衰老叶片中,抗坏血酸是主要的活性氧清除剂。5.对灌浆过程抗氧化代谢中各种酶活性进行测定,结果表明:每克鲜重中抗氧化酶活性随着灌浆的进程逐渐降低,而每毫克可溶性蛋白中抗氧化酶活性都随着衰老逐渐升高,表现趋势为衰老初期和中期小幅度变化,衰老晚期大幅度变化。测定结果表明小麦旗叶衰老过程中可溶性蛋白含量降低。这些说明在灌浆过程中抗氧化酶的降解速度可能慢于其它蛋白的降解速度,相对提高了消除活性氧的能力。6.对小麦旗叶蔗糖、淀粉、果糖和非结构性碳水化合物含量以及与碳水化合物合成的关键酶进行了测定。他们的变化基本一致,随灌浆的进程均呈“低-高-低”的变化特征。花后10-20 d峰值的出现,是因为此期叶片合成能力较强,籽粒正处于体积扩大和粒重快速增长阶段,利用、转化和储存同化物能力较低,使之在叶中有较多积累。花后20 d后碳水化合物含量下降迅速,可能是由于此时籽粒转化利用能力衰退的结果。SPS和SPP酶活与蔗糖合成是同步的,SSS和ADPGase酶活变化与淀粉的含量也是同步的。7.通过旗叶类囊体膜蛋白的Western杂交分析研究灌浆过程中旗叶类囊体膜PSII相关蛋白的变化的结果表明,在籽粒灌浆过程中,尤其是灌浆后期,植物体内的PSII活性会受到抑制,产生抑制的主要原因是由于类囊体膜蛋白的损失,主要与PSII反应中心CP43、CP47和OEC33蛋白含量的下降有关。更多还原

【Abstract】 In this article, the characteristics of grain filling and light saturated photosynthesis of flag leaves during grain filling period of field-grown wheat plants were investigated. The results are following:1. The studies of grain filling processes and rates to five wheat species show the 1000-seed weight accords with Richards equation to be“S”curves. After 5 d after anthesis, all species enter the rapid grain filling period (RFGP), and they all have one peak during the grain filling period.2. The studies of chlorophyll and chl a/b show that: the chl and chl a/b significantly correlated. The chl remains constant in the early and mid period of grain filling process and begins to decrease significantly in the last period.3. The results chlorophyll fluorescence showe declines of PSII indicate that the chl content and Pn occur simultaneously. Before 20 d in the grain filling, the decrease of Fv’/Fm’is associated with the closure of PSII centers and an enhanced thermal dissipation in the PSII antennae. The results of photosynthesis, chlorophyll content and chlorophyll fluorescence suggest that PSII apparatus remained functional to use the light energy more efficiently in the early and mid period.4. The changes of contents of ASA, GSH in morning and noon of flag leaves were investigated. The content of ascorbate and the ratio of ASA/(ASA+DHA in flag leaves increased during grain filling period. But the contents of GSH+GSSG and GSH decreased. It is suggested that the ascorbate is the main antioxidants in senescence flag leaves.5. The activities DHAR, MDHAR, ASPX, GR, CAT and SOD during grain filling in flag leaves of field grown wheat were investigated. Their activities expressed on leaf fresh weight decreased during flag leaf senescence, but the activities expressed on the protein content increased. These data suggest that the antioxidative enzyme’s degradation is slower than the rate of total soluble protein degradation, which may relatively improve the enzyme’s function of scavenging the active oxygen.6. The contents of carbohydrates of flag leaves show that the trends of carbohydrates are all“low-high-low”. The changes of the key enzymes activities in sucrose synthesis (SPS and SPP) and the key enzymes of starch synthesis (SSS and ADPGase) showed the same trends with the sucrose and starch respectively.7. Western-blotting of thylakoid membrane on flag leaf of wheat was studied, in order to investigate the changes of some PSII proteins with the consenescence of the flag leaf. The results show that the decrease in PS II activity may be due to dissociation of certain thylakoid peptides from thylakoid membrane, mainly as a result of decrease in D1,CP43 and CP 47 protein contents of PS II reaction centre and OEC33 protein of oxygen-evolving complex during the grain filling stage, especially the late stage.更多还原