Molecular- and Cell-Biological Study of Plant Senescence

石井观察到，CO^2的扩散阻力增加，导致衰老叶片的光合作用效率低下。Katoh从光合作用的各种测量结果推断，在遮荫条件下，光合作用的一部分下降可以看作是光化学反应系统对低光强的一种适应。由于已知RuBisCO蛋白在衰老叶片中显著减少，Mae成功地在衰老水稻叶片的叶绿体中检测到其大亚基的降解产物。Fukuda成功地分离出发育中的管细胞分子特异性蛋白酶的cDNA克隆，其中细胞成分与衰老细胞类似地降解。Watanabe发现，胞质谷氨酰胺合成酶基因的三个成员中的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。他还发现依赖于NADH的谷氨酸合酶特异性地定位于非常年轻的未展开的叶片和发育中的谷粒中，并且因此负责接收从源器官转移的谷氨酰胺。川崎在制备RFLP标记以分离负责水稻中的保绿突变的基因方面取得了进展。Azumi分析了萝卜黑暗诱导基因启动子区在转基因烟草中的功能。

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.