Aleksandrushkina N I, Zamyatnina V A, Bakeeva L E, Seredina A V, Smirnova E G, Yaguzhinsky L S, Vanyushin B F
Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119899, Russia.
Biochemistry (Mosc). 2004 Mar;69(3):285-94. doi: 10.1023/b:biry.0000022059.97294.bc.
Apoptosis was observed in the coleoptile and initial leaf in 5-8-day-old wheat seedlings grown under normal daylight. Apoptosis is an obligatory event in early wheat plant ontogenesis, and it is characterized by cytoplasmic structural reorganization and fragmentation, in particular, with the appearance in vacuoles of specific vesicles containing intact organelles, chromatin condensation and margination in the nucleus, and internucleosomal fragmentation of nuclear DNA. The earliest signs of programmed cell death (PCD) were observed in the cytoplasm, but the elements of apoptotic degradation in the nucleus appeared later. Nuclear DNA fragmentation was detected after chromatin condensation and the appearance in vacuoles of specific vesicles containing mitochondria. Two PCD varieties were observed in the initial leaf of 5-day-old seedlings grown under normal daylight: a proper apoptosis and vacuolar collapse. On the contrary, PCD in coleoptiles under various growing (light) conditions and in the initial leaf of etiolated seedlings is only a classical plant apoptosis. Therefore, various tissue-specific and light-dependent PCD forms do exist in plants. Amounts of O2*- and H2O2 evolved by seedlings grown under normal daylight are less than that evolved by etiolated seedlings. The amount of H2O2 formed in the presence of sodium salicylate or azide by seedlings grown under normal daylight was increased. Contrary to etiolated seedlings, the antioxidant BHT (ionol) did not inhibit O2*- formation and apoptosis and it had no influence on ontogenesis in the seedlings grown under normal daylight. Thus, in plants grown under the normal light regime the powerful system controlling the balance between formation and inactivation of reactive oxygen species (ROS) does exist and it effectively functions. This system is responsible for maintenance of cell homeostasis, and it regulates the crucial ROS level controlling plant growth and development. In etiolated plants, this system seems to be absent, or it is much less effective.
在正常日光下生长的5 - 8日龄小麦幼苗的胚芽鞘和初生叶中观察到了细胞凋亡。细胞凋亡是小麦植株早期个体发育中的一个必然事件，其特征是细胞质结构重组和碎片化，特别是液泡中出现含有完整细胞器的特定小泡、细胞核中染色质浓缩和边缘化以及核DNA的核小体间断裂。程序性细胞死亡（PCD）最早的迹象在细胞质中被观察到，但细胞核中凋亡降解的成分出现得较晚。在染色质浓缩以及液泡中出现含有线粒体的特定小泡后检测到核DNA断裂。在正常日光下生长的5日龄幼苗的初生叶中观察到两种PCD类型：适当的细胞凋亡和液泡崩溃。相反，在各种生长（光照）条件下的胚芽鞘以及黄化幼苗的初生叶中的PCD只是典型的植物细胞凋亡。因此，植物中确实存在各种组织特异性和光依赖性的PCD形式。正常日光下生长的幼苗产生的O2和H2O2的量比黄化幼苗产生的少。在水杨酸钠或叠氮化物存在的情况下，正常日光下生长的幼苗形成的H2O2量增加。与黄化幼苗相反，抗氧化剂BHT（离子醇）不抑制O2的形成和细胞凋亡，并且对正常日光下生长的幼苗的个体发育没有影响。因此，在正常光照条件下生长的植物中确实存在强大的系统来控制活性氧（ROS）形成与失活之间的平衡，并且它有效地发挥作用。该系统负责维持细胞内稳态，并调节控制植物生长和发育的关键ROS水平。在黄化植物中，这个系统似乎不存在，或者效果要差得多。
