Changes in Protein Content and in the Structure and Number of Chloroplasts during Leaf Senescence in Rice Seedlings
Changes in Protein Content and in the Structure and Number of Chloroplasts during Leaf Senescence in Rice Seedlings
复制标题
水稻幼苗叶片衰老过程中蛋白质含量及叶绿体结构和数量的变化
DOI：
10.1093/oxfordjournals.pcp.a077797
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发表时间：
1989
影响因子：
4.9
通讯作者：
S. Katoh
中科院分区：
文献类型：
--
作者：
H. Hashimoto;M. Kura;S. Katoh
为了研究水稻幼苗叶片衰老过程中光合作用的失活是否与叶绿体的损失有关，进行了两种类型的试验。叶片可溶性蛋白和不溶性蛋白含量在衰老过程中均呈下降趋势，其中可溶性蛋白的损失速度大于不溶性蛋白的损失速度。放氧速率与可溶性蛋白质水平呈良好的正相关。光合作用的失活也与大部分不溶蛋白质的损失呈线性关系。因此，光合作用能力的丧失可归因于叶片衰老过程中相关蛋白质和酶的降解。电子显微镜观察发现，衰老导致基粒和基质类囊体定向障碍，淀粉颗粒数量减少，质球大小和数量增加。老叶中出现了由20~30个类囊体组成的大基粒。除了这些超微结构的变化外，叶绿体的大小也显著减小。此外，衰老过程中叶肉细胞中的叶绿体数量也显著减少。因此，叶片蛋白质的损失和光合作用的失活都与水稻幼苗衰老过程中叶绿体总量的减少有关。
Two types of experiment were carried out to examine whether or not the inactivation of photosynthesis is related to loss of chloroplasts during foliar senescence of rice seedlings. Levels of both soluble and insoluble leaf proteins decreased during senescence, the loss of the soluble proteins being faster than that of the insoluble ones. There was a good positive correlation between the rate of oxygen evolution and the level of soluble proteins. The inactivation of photosynthesis was also linearly related to the loss of a major fraction of insoluble proteins. Thus, the loss of photosynthetic ability is ascribable to the degradation of relevant proteins and enzymes during leaf senescence. Electron microscopy revealed that senescence caused the disorientation of the grana and stroma thylakoids, a decrease in the number of starch granules, and an increase in the size and number of plastoglobuli. Large grana consisting 20 to 30 thylakoids appeared in aged leaves. In addition to these changes in ultrastructure, there was a significant decrease in the size of chloroplasts. Furthermore, the number of chloroplasts in mesophyll cells was also notably reduced during senescence. Thus, the loss of leaf proteins and inactivation of photosynthesis are both related to the decrease in the total mass of chloroplasts during senescence of rice seedlings.