Molecular- and Cell-Biological Study of Plant Senescence

Ishii观察到CO^2的扩散阻力增加，导致感官叶片的光合作用效率低下。Katoh从对光合作用的各种测量中推断，遮荫叶片的部分光合作用减少可以看作是光化学反应系统对较低光强的一种适应。由于已知RuBisCO蛋白在衰老叶片中显著减少，Mae成功地检测到了其大亚基在衰老水稻叶片叶绿体中的降解产物。福田成功地分离出了一种针对发育中的气管元件的蛋白酶的cDNA克隆，气管元件的细胞成分与衰老细胞的降解相似。渡边发现，胞质谷氨酰胺合成酶的三个成员基因中有两个在萝卜衰老过程中受到激活调控。Yamaya发现这种谷氨酰胺合成酶只存在于水稻的维管束细胞中。他还发现nadh依赖的谷氨酸合成酶专门定位于非常年轻的未展开的叶子和发育中的谷物，因此负责接收从来源器官转运的谷氨酰胺。川崎在准备RFLP制造者分离水稻中负责保持绿色突变的基因方面取得了进展。Azumi分析了他从萝卜中提取的黑暗诱导基因启动子区域在转基因烟草植株上的功能。

Ishii observed that diffusion resistance of CO^2 increases to result in inefficient photosynthesis in senesing leaves. Katoh deduced from various measurements of photosynthesis that a part of decrease in photosynthesis in shadowed leaves can be regarded as a kind of adaptation of photochemical reaction system to the lower light intensities. As RuBisCO protein was known to markedly decrease in senescent leaves, Mae was successful in detecting the degradation products of its large subunit in chloroplasts from senecing rice leaves.Fukuda was successful in isolating cDNA clones for a protease specific to developing tracheary elments, in which cellular constituents are degraded similarly to senescing cells. Watanabe found that two of the three members of cytosolic glutamine synthetase genes are activated in senescing radish regulated. Yamaya found that this glutamine synthetase localizes only in vascular bundle cells in rice. He also found that NADH-dependent glutamate synthase localizes specifically in very young unexpanded leaves and developing grains, and is, therefore responsible for receiving glutamine that is translocated from source organs.Kawasaki had a progress in preparing RFLP makers to isolate a gene which is responsible for a stay-green mutation in rice. Azumi analyzed the function of promoter region of his dark-inducible gene from radish in transgenic tobacco plants.